You may have overlooked, or else I missed, another key benefit of liquid fuels in aircraft vs batteries and that is that as the fuel is burned the aircraft actually gets lighter and easier to propel. The weight of a battery has to be carried regardless of whether it is full or depleted. Great video and thank you
Right and also the jet engine provide electricty for the aircraft, pneumatic power for pressurization/AC system, mechanical energy for the hydraulic systems, and heat for anti icing system making the equations even more dificult for jet electrification
Well there is fuel cells, which with hydrogen cells you’re just producing water as you extract energy so you can just dump it. Although there is the caveat that it would likely not work for long haul flights as you need altitude, which dumping water out of an aircraft is known to freeze in the air and to the fuselage ; which in order to prevent you mix in an additive to lower the freezing temperature (often a blue liquid I can’t remember the name of), which has the potential to be toxic like standard antifreeze.
On top of potentially altering the chemistry of the fuel cell depending on which point you include the additive I.e in the tank pre-flight or at the exit
In my opinion unless we improve energy density, toxicity, recycling practices, lifespan, and safety factor of current battery technology, followed by charging them with a "clean" power grid, which much of our country does not have, then the "easy" part is not really helping all that much... kind of just keeping the problems of production, mining, toxicity, and emissions in other countries (just like right now) the total resources required to manufacture lithium ion batteries specifically are rarely considered, neither is the 10 year or less average lifespan before complete replacement (usually meaning environmentally terrible but cost saving recycling) along with the fact that petroleum, while not being consumed for energy is still needed for around 15-40% of a modern car's component production (probably higher moving forward)... unless we have a low carbon output power grid already in place and enforce strict requirements on the mining/production/recycling of current technology batteries made in other countries, the North American EV concept/mandates will likely just be another subsidy propped money printer for large corporations without very much positive total environmental impact when viewed as a whole, rather than just concentrating on carbon emissions alone... 🤷♂️ Fun fact one EV passenger car fire often requires 15,000-30,000 gallons of water (Tesla claims 3,000-8,000 in thier first responders guide book) for extinguishing and "tanking" (keeping submerged in a specialty tank) for 24-72 hrs, this water is then highly contaminated with not only standard car fire toxins, but all the highly toxic materials of the battery pack. Typical combustion engine passenger car fires m average around 300 gallons to extinguish, no dunk tank required. If it wasn't for terrorism I feel we could definitely have higher energy density battery packs or even better hydrogen fuel cells on the menu... its hard to use petroleum as a psuedo high explosive, but a 21700 battery with 5x-10x the energy density or all the hydrogen you want at every fuel pump? I think the department of homeland security will be stepping in front of scientific achievement and progress, sadly probably neccesarily 🙁 Thoughts?
@@rafqueraf but how environmentally friendly is that really... if implemented using current methods and infrastructure? I think people focus too hard on carbon emissions, overlooking the cascading effect of negative environmental impacts 🤷♂️ *see my long winded comment above for a short list of my reservations about widespread EV adoption...
Excellent video! One point I wanted to add not covered in the video was recharge times, when a plane is on the ground airlines want to have it back in the air as quick as possible, refuelling is very quick, but if a plane is sitting for a few hours (I’d guess at least) to charge up its massive batteries, that might severely affect the turnaround time for planes on the ground. Just another thing to think about.
That is a good point. The website for the 19-passenger electric plane I talked about says they can charge it in 40 minutes, and that the charger itself (not the cost of electricity) is $500,000. We'll see of course.
Charging time can definitely be solved. Though the power source needed would be huge. But batteries will remain heavy and not suitable for larger planes and long distances.
@@northsimulation3386 The problem with fast charging is the same on both scales. We see the issue of fast charging smartphones heavily degrading the batteries, and this is the same problem when you charge large quantities of battery cells. I would take a vague guess that this is even more of an issue due to the power requirement to "push" through it. Apart from the degredation, you require more energy for the fast charge, which essentially means it's less efficient due to energy wasted. And we waste already way, WAY too much on simple electric transfer. Electric energy needs to become far more localized. but we as a general society are not educated enough to have a small nuclear powerplant in the basement of every apartment block.
@@northsimulation3386 Seems to me, each battery cell (18650, 2170, flat pouch, 4680, whatever) has a maximum rate of charge (dependent on capacity, state of charge, and temperature). There's no conceptual reason you can't just charge 10000 cells at the same time, feeding each cell the same power you would feed it if you were only charging 1 cell. In theory it would take the same amount of time. Of course, nobody actually _does_ charge each cell in parallel. There are physical limits, with the amount of wiring and the amount of charge controller / battery management hardware. So you have to strike a balance. But that doesn't change the _concept_. The other physical limit is how many kW you can supply to the battery pack. That relates to your grid supply, your cable thickness (or how many charge ports and cables you can use at once), the voltage you're willing to use. This is presumably why the airplane charger is half a million bucks.
As others have noted, the more jet fuel is used the lighter the aircraft gets which makes it more efficient but there's a safety angle as well. If a jet has some kind of emergency and needs to land it can lighten itself by dumping fuel. You see, jets don't really want to land at their max takeoff weight due to the forces involved. It's one thing for a regional aircraft due to the shortness of the flights but long haul and even medium length travel make it difficult.
To be fair, planes are this "fragile" because of economical reasons. Basically, they saved weight by reducing structural integrity of the plane to point where it is not safe to land with takeoff load for the sake of efficiency. All I want to say that it is possible to have planes that can carry a battery and still land safely. I however believe that air travel is one of only a few sectors where it is not advisable to go electric. Hence I fully agree with the biofuel points laid out in this video.
@@adrianmartin7344 They are not too fragile to land safely, all commercial jets can land safely at max GTOW.(military may be different) With safety defined as not causing injury to people or other property. The published specified max landing weight is the weight where a safety inspection of the landing gear and specified air-frame components is mandatory following the landing, simply because the forces may have been between the design strength and the ultimate strength. If a the design load for a normal landing(even a rough normal) is defined as 100% and the required strength safety factor is 150% of design load, then landing at max takeoff weight might have the plane at 115% of design load. Which is less than the desired 50% safety factor but still well below actual design strength, hence the inspection is needed. There may also be simple issues like overheated brakes that need new pads or excess tire tread wear from higher touchdown speed. They may also reduce fuel load fuel to reduce the stopping distance, even if they could squeeze in they simply want to expend the margin of safety when things are already going wrong. Smaller jets usually already have a short enough landing roll to give plenty of margin even when fully loaded, while a fully loaded longhaul may require the longer runways in a region even under good conditions. When things are very bad they may want to reduce fuel as a fire hazard unrelated to weight stresses.
For flight specifically, jet fuel is the obvious choice. If we electrify most other things from non-GHG sources, there will be plenty of opportunity to offset, or remove the contribution airplanes make. Nature came up with the stuff, and it's positive properties are orders of magnitude better than anything we could possibly invent. Our combustion machines still have room for improvement, but the fuel, for flight, is aces.
I have to agree, this was my conclusion too. If we manage to decarbonize everything except air travel, than thats what we should do. First of it is a small portion of the emissions so we only have a fraction of the problem left, and even that can be handled with carbon capture and sequestration. I'd further say that we could be a lot more optimistic and happy about our position in the fight against climate change if we were at the point by now, where air travel is the most of our concerns.
I came to a similar conclusion for the majority of maritime transport, despite the more feasible non diesel options. To me it makes far more sense to invest in technologies which deliver the largest bang per buck. The "!" (bang) is of course the largest reduction in worldwide carbon dioxide emissions in the shortest time.
Obe big problem with corn->fuel: It is NOT carbon neutral. Hell, Corn->Ethanol is not carbon neutral. Corn doesn't suck up anywhere near enough CO2, especially when you factor in the methods used to convert it.
@@Chupacabras222 What he means is, the resources expended to grow corn end up releasing more carbon than the corn absorbs, and as a result is carbon positive.
I think the implied point of the video is that as the rest of our infrastructure goes electric the farming industry will become more green than it currently is. This might not make corn -> fuel completely carbon neutral, but it should offset it somewhat at least. and would almost certainly be better than what is currently being used no? I mean in the end people are just NOT going to stop flying in significant numbers anytime soon. So finding some kind of more green means to fuel the aircraft industry seems important.
I love that something I first heard of in the original Alpha Centauri Civ game is real and practical. It's a crime that this channel does not have a bajillion views.
Awesome video as always, Prof! One of my biggest concerns is that here in the UK, electricity is around 15p per kWh and gas is around 3.5p per kWh. We need to drive this cost way way down before we can move on to everything being electric otherwise our already massive heating bills are going to become literally unaffordable for a lot of people.
The electric car will still likely be cheaper to operate. ICE vehicles are only about 33% efficient, they waste 66% of the energy put into them. A BEV is about 80% efficient, (you lose about 10% at the motor and another 10% on the charge discharge cycle) so it's not as simple as looking at the cost of the energy you are putting into the car, you also have to consider how efficiently it is used. An efficient heat pump is the best way to heat your home with electricity, and often results in much lower energy costs.
@George Mann Don’t natural gas or methanol fuel cells actually extract the hydrogen from those fuels, and in the process produced CO2? You only get zero CO2, when using a fuel, like hydrogen, that has no CO2 in it.
In a similar way to kerosene for transport category aircraft, the legacy investment in natural gas has to be considered. "The Dash for Gas" back in the 1990s looked stupidly short term to me at the time even though I didn't know that Peak Oil and Gas Production from The North Sea would be around 1999/2000.
Thank you. There are still people who think batteries are the way for air transport, and when they're shown the facts, they hand-wave about 'technology'. Perhaps it would be worth doing some exploration on the physical limits of batteries. One small comment on propulsion: most commercial 'jets' are in fact turbo-fans, and the jettish part mostly provides energy to drive the great big fan up the front. So they could be electrified, provided a viable energy storage system could be provided for the electric motors. But best in the short term would be a zero-carbon fuel that was a drop-on replacement for existing fuel: does that process you mentioned produce a fuel that can be used without any modifications? Can it be mixed with kerosene (that would be important from a safety angle)?
Whenever there is a discussion about getting rid of fossil fuels in aviation there is nearly always one topic that is overlooked: General Aviation (GA). For those who are not familiar, it's a blanket term that covers everything from Cessnas to Lear Jets. While it is not directly connected to Commercial Aviation (a.k.a. the airline industry) it plays a vital role there because it supplies the industry with all of its pilots. The GA industry in the US and Canada is so massive that most other countries' airlines outsource their primary pilot training to the US. Meanwhile, GA primary flight instruction in the US remains largely a cottage industry despite the existence of for-profit aviation focused institutions like Embry Riddle. Most of the mom and pop flight schools like the kind that you'd find at your local community airport run on a razor thin profit margin operating aircraft that are often nearly a half a century old. Approximately 60% of the single-engine piston fleet in the US is comprised of aircraft made before 1980. 20% is composed of mass produced aircraft made after 1980 and the other 20% are amateur built kit aircraft that are intended for personal use and are prohibited form being rented out for flight instruction by FAA regulations (the FFA, on the other hand, has not released any official guidance on these aircraft). This means that unlike the US automotive or airline fleets, the US single-engine piston fleet that teaches nearly the entire world how to fly is not going to simply phase out the vast bulk of its old aviation fuel airplanes after 20 years in favor of new ethanol kerosene or electric models. Modifying the current ones may be technically possible, but it is economically unfeasible as modifying anything on a type certificated airplane comes with massive costs. Performing an engine swap can cost several thousand dollars just in labor costs while the engines themselves may costs many tens of thousands of dollars, even on a half century old airplane. Meanwhile, new airplanes can costs many hundreds of thousands of dollars. The reasons behind the age of the current GA fleet are many but, as you can see, cost is one of the reasons. This is why the flight training industry in the US still uses these old airplanes. Any significant change in cost to the GA fleet could lead to a near total collapse of the flight training industry in the US and could turn the pilot shortage situation that currently exists in the airline industry into a crisis. I'm not sure how to solve this issue, but its something that virtually nobody who talks about decarbonizing air transportation even mentions.
@@brownro214 Not anywhere near enough to satiate demand, though. And the military uses civilian piston-engine aircraft for initial flight training, anyway.
Corn-based Ethanol doesn't really seem like such a great approach to me, mostly due to a combination of two main reasons: 1) The ethanol fuel energy balance is just kinda bad for corn ethanol, and 2) Land use. It sort of feels like it defeats the purpose. Corn ethanol's biggest advantage seems to be that it has a huge incumbency advantage, so to speak. Lots of investment in it and a lot of political clout to go along with that.
I suppose the biggest reason corn based ethanol is so relevant here is not that it is the best crop to produce ethanol, but because the land used for that corn, likely, has no immediately better use. (ie in the US there is a lot of corn land that doesn't have much else competing for the space) Sugar cane ethanol for example is much more efficient in some senses, but can only be grown in certain areas. I imagine many competing crops would be the same, as well as any other way of synthesizing/creating a fuel. More of a complex optimization problem than simple efficiency, though of course the results can always change. And there may be plug and play improvements the real professionals are considering
Hi bypass ratio turbo-fans, the types of jet engines that power commercial aircraft, develop around 90% of their thrust via the primary compressor, so the actual exhaust of the burning fuel only provides around 10%. Turning one of these primary compressors via an electric engine is, therefore, theoretically possible, but the rest of your arguments remain valid. Thanks prof!
Professor I think you might have missed some crucial points in the simplification: 1) Most of the energy used in the Industrial sector isn't electricity for a reason, we cannot electrify steel making, iron ore processing, concrete and cement. All of these require carbon-based inputs. The biggest outputs of our civilization: Steel, Concrete, Cement and Plastics cannot be made out of electrons, they come from coal, coke, oil, nat gas etc. The only part we could electrify is some of the heat generation processes in those heavy industries, and only part of it. 2) In transportation, one of the main uses of diesel is in heavy machinery (trucks, tractors etc) which cannot be electrified, and the same goes for Shipping, the driver of global economy and commerce. Shipping will have to rely on diesel (until possibly hydrogen comes into the picture in some decades). A big chunk of the industrial and transportation sectors will remain fossil-fuel based.
As a UKsian my principal focus is a "killing two birds with one stone" approach, destroying the radioactive artefacts we have stored at Sellafield by fission and producing process heat for industrial applications.
You overlooked ammonia. It can be burned directly in a turbojet if you don't mind the nitrous oxides, but can be easily split by catalyst to burn hydrogen only.
The is the possibility of what our navy blue is looking into. That is the production of jet fuel from sea water. This involves extraction of C0² from ocean water and attaching the H to the carbon and dumping the O² into the air. Takes a certain amount of energy to do this but nuclear reactors have this in abundance. So far the best way to get the weight a volume unless some sort of nuclear reactor is used. Reactors would have the added benefit of eliminating all pathogens during flight.
Love your videos Prof. Ruzic! What is the net Carbon impact of using corn to produce ethanol fuel then burning that fuel? Is it zero because the Corn plants extract carbon from the atmosphere to produce the corn? I assume there is carbon currently because of the tractors and trucks used in production are probably hydrocarbon based, but if they could be electrified would it be net zero? Or does carbon leak into the system some other way?
Airbus did a test with liquid hydrogen, and found that the whole fuselage is needed to be filled in order to cross the Atlantic Batteries are simply not for airplanes; they are too heavy and do not have near the same density as kerosene or more accurately,(jet fuel). There is simply no near-future replacement. Fuels also are required by the FAA to have certain lubercating properties, but more importantly, flash points. Natilural gas has not been proven to burn at the same temps as jet fuel, while having similar viscosity, Ect. Batteries are also double bad because unlike fuel, the weigh the same regardless of energy state; a empty fuel tank has 10% fuel (unburnable) but a empty battery weighs 100% of it's full mass.
Have you looked into carbon engineering's fuels? They are made from sequestered co2 from the air. I often wonder about pairing one of their plants with nuclear power. One of their processes requires a temperature of 900c. Which might be too hot to heat up directly with nuclear heat. But they could do a two stage system where it's mostly heated using nuclear thermal, and the rest by using an electric process. A plant could be built close enough to an airport to reduce shipping costs also.
This is the obvious solution and it's what the world will inevitably converge to over time as reality and physics ultimately wins over ideology and beliefs.
@@zolikoff I agree, as world population continues to grow we will likely require that land for growing food. Synthetic methane is certainly possible, Musk intends to use the method to provide fuel for a return trip from Mars. I just wonder if it could be produced in sufficient quantity and at a competitive price, to replace fossil fuels for combustion engines.
@@bobthebomb1596 it's hard to say as it's new technology. Carbon Engineering lowered the price of sequestered CO2 by using off the shelf water tower (cooling tower?) components. So they got to use the economics of scale somewhat. The material they use for the carbon capture I believe would need that as well. I could be wrong about the details here, but that's the general idea. How it's powered I imagine is a big component in price.
This is a good analysis. I'm concerned about biofuels displacing farmland used to feed people, but I didn't know the US already produces enough ethanol for air travel. In the long term, it's probably easier to make new jet engines that can burn ethanol directly or farms could produce biodiesel, though according to the chart at 3:15 the energy per weight isn't as good. I'm also hoping direct carbon capture companies like Carbon Engineering become cost competitive. The technology works, but it could remain too expensive. Ammonia could work for container ships. It's twice as heavy as jet fuel, it's liquid at around 8 bar, and can be produced using electrolysis instead of stripping hydrocarbons. Maersk is already exploring this.
It looks like Liquid Hydrogen requires more volume than jet fuel but is lighter weight seems like that could be a realistic option to keep the turbine engine design I've seen that GE is building hydrogen turbine engines for electricity production. I've also read that that it could be done with Ammonia which could be a cheaper fuel source.
Probably depends on how that table accounts for storage weight. If the larger tanks required push the actual number up, it's basically dead on arrival for larger planes. Also embrittlement is gonna carry a cost on the fuel systems, but not like that'll stop anyone. Might Concorde a model or two.
Love your videos, Professor. Thank you. I'd be really interested in a followup video on using something like Hydrogen as a fuel. I think it meets a lot of the challenges you've raised.
@@illinoisenergyprof6878 Also storage tanks of compressed hydrogen are heavy. I think the weight of tanks in hydrogen cars is an several times the weight of the hydrogen it can store. And then you've got a plane at higher altitudes so the pressure ratios will be even more intense.
We remember airships: R38, R101, Shenandoah, Akron, Macon, Hindenburg... Any airship capable of carrying a serious useful load is so large that the weather at one end is different than the weather at the other, and sooner or later, nature tears it apart.
You'd have to figure out what to put in them, right? Hydrogen is ... problematic. Helium ... I suspect we'd run low on the global supply of helium pretty darned quickly.
They only have very niche uses today because of that, the speed and lift limits and the gas limitations, but man they are still so cool. Here's to the engineer that someday convinces his boss that an airship is the right vehicle for some crazy job.
Prof makes me think of giants like Feynman and Sagan sometimes in the way he takes incredibly complex subjects and makes them engaging and accessible to the layperson.
Thank you very much for these videos. I have been subscribed for some time now and It makes my day to see a new video. No matter what one’s belief is concerning climate change, or politics, we as a race are responsible to be a good custodian of our planet. Your videos often address solutions that would make us as a people more efficient and better as caretakers. It’s not controversial to want to make the “world a better place.”
One thing you have overlooked (or omitted for simplicity sake) is that jet engines are the least efficient engines. The engines used in cargo aircraft are high-bypass turbofan which derive the vast majority (approx 80%) of their thrust from the first stage, and only a minor part from the air passing through the core.
I have been checking the comments to see if anyone commented about ducted fans. I believe the idea being proposed for electrifying planes is to have a motor drive a ducted fan, ie. the jet engine core is replaced with a motor. So the speed of the plane shouldn't be impacted, as it would be if propellers were used, as suggested. Using electric motors has the benefit of not having to waste energy on the compressor stages and lost energy in the hot fast moving turbine exhaust gases. However, I wonder what the size and weight of the electric motor required will be. Jet engines for planes aren't measured in shaft power, but the GE Frame 9 used industrially for turning generators, compressors etc. has a shaft power of 132MW. I don't know how close in size it is to the jet engine core on a plane, but the equivalent motor is going to be pretty big.
Some points to add to the comparison with Teslas AA battery. Their small size multiplied by the number we need adds up to a big ammount of weight and volume. It would be better to compare with industrial grade battery racks. Fuel pipes and pumps are also quite heavy in aircrafts. But one big big advantage of fuel is that once it's burnt the weight is out. Most airliner planes cannot land with the same weight they took off with.
There are 2 important aspects missed on your analysis. 1 - Lapcat from REL inc (UK), using the SABRE engine. An air breathing rocket engine with LH2 as the fuel. Flight at Mach 5.5 / 80-90k ft altitude. Hydrogen can be easily produced from H2O either using nuclear heat or electrolysis. Proposed aircraft is ultra long range capable, even London or LA to Australia non stop possible. 2 - Electric Fan like engines powering high subsonic or even supersonic aircraft. Fossil engines are very limited to how much O² you can scoop from the atmosphere. But electric Fan engines are NOT limited by how much oxygen is available at cruising altitudes. Full power available even at 70000ft where the air is super thin. As long as enough lift can be produced a LOT of the downsides from heavier/bulkier batteries can be offset. Not enough to fly long haul routes, but enough to fly perhaps routes up to 2000 to 3000km, which encompasses more than half of the current air travel fuel consumption. Lithium cell technology is far from its ultimate limits while Jet fuel isn't going to get anymore energy dense. Expect at least a doubling of energy density both by weigh and volume improvement over the next decade. For instance the Tesla tabless 4680 design improves on the 2170 by at least 25%. Elon Musk stated that current Lithium energy density (from a few years ago) was insufficient to make compelling electric transport aircraft but that a doubling of energy density from Tesla Model S era 18650 (or a 50% improvement from 4680) would be enough to start making compelling air transport. The other very significant possibility is since electric engines are much lighter than big fossil turbofans, its viable to design a vertical take off / landing aircraft, which fully eliminates the need for flaps/slats and wing designs that must produce enough lift at lower indicated airspeed. This allows to design wings that only produce enough lift for climb/cruise at higher indicated airspeeds which reduce drag some more.
If we electrify all ground transportation and short sea and air transportation then the biofuels we make are enough to cover the rest, long haul flights, transoceanic shipping and helicopters. We "only" need like 3 times more electricity than we have today but that is doable over a couple of decades.
@@N330AA Having enough guards on board to prevent the risk of hijacking and potential nuclear terrorism might make that economically non-viable. But of course technically it works as US aircraft carriers and Russian ice breakers shows. Probably better to have the nuclear reactor on land making some sort of carbon neutral fuel for ships.
These videos really show that engineers know what to do, there just isn't anyone paying them to take us there. I have a patent pending for an electric car smart charging method that allows EVs to act as long term energy storage. I know everyone talks about it all the time and everyone knows it's the future, but nobody has bothered to develop it yet. It's so ripe for development I was able to take it to the next level in my free time.
@@AlexWaardenburg teslamotorsclub.com/tmc/threads/arbitrage-with-power-wall.156157/ look up EV Arbitrage. On the introduction of the 2022 Ford F150 Lightning (EV), they state multiple times that if your pickup is charged up and you get a power outage at your home, the battery in your EV could possibly power your house for a few days.
Hi ! I'd also like to believe that electrification is the path to decarbonization but the lack of investment in nuclear power by western countries is very worrying and seems incompatible with an increase in electricity demand. Thanks from France.
You French have been building half of the Champagne region full of wind mills for the last couple of years. Very usefull, given the fact what 80% is nuclear, and a reactor can't be switched of due to xenon poissoning. Thanks EU.
We will get the reckoning in 15 years when all those wind turbines and solar panels go down and the waste material need to be disposed of. I bet the developed nations will just dump the waste to developing nations like what they did with the plastic recycling scam.
I seem to recall that there were concepts in the 1950’s for nuclear powered aircraft propulsion systems. Now the appetite for nuclear power in transportation systems is largely limited to military budgets, but all the same - nothing else has more energy density! Therefore it must be worth exploring the idea a little in the name of decarbonisation. So the most obvious question is, can you do it, and make the contamination risk inherently safe in the event of a catastrophic air accident? The previous discussions about pebble bed reactors were interesting. If the fissile material is contained inside glass pebbles and these pebbles can withstand the forces involved in an air accident, maybe the mop up exercise afterwards is made much easier.
A bit off-topic perhaps, but it would have been nice to see some discussion of rail travel as an alternative to aviation on short to mid length overland routes. Rail is easy to electrify and travel speeds are competitive with short range flights.
Prof, thanks for making this video. Provides great insight into what can be achieved with electrification. I am wondering though about ethanol based fuels. These are produced more cleanly, but while burning them, don't you produce the same amount of CO2 anyhow? Also converting these bio types from food to fuel comes at an energy cost. You can electrify the systems that runs the conversion, but no matter what, unless there is some breakthrough in battery tech that decreases the weight significantly, while increasing the weight per unit energy, air travel will have to be done with fuels, or make air travel so expensive, only the rich can afford it. On another note, how about hydrogen fuel cell tech for air travel? Is this not safe as regular kerosene, or costs too much to mass produce?
Never mind. Should have seen the table/graph you provided at around 2:50. It says cooled liquid hydrogen is a quarter of the energy output of jet fuel. Unless this is not the same, but I doubt it.
the thing about corn based ethanol is that, well it comes from corn. The way that the corn actually grows is by taking all the carbon it needs from the air and thus, when you burn the fuel, the carbon in the air is not any higher than it was earlier.
Might have been overlooked or maybe I missed it, with fuel, you only have to carry one component of the reaction. Air is always available and exhaust is dumped overboard.
The best way to decarbonize air travel is replacing most short haul flights with high speed rail and leave long haul alone. Unfortunately that's a tall order for USA but Europe and Asia are well suited for that transition.
Ironically flights in within Europe are often cheaper and much faster than rail. High speed rail might be a good alternative to cars. For example: $82 and 2.5 hours to get from Barcelona to Prague by plane vs $240 and 24 hours by rail?
Yes. Using jet fuel to take off and climb, then electricity to cruise would certainly save energy. You don't get all the way, but hybrids, like with cars, do get you part way there.
@@illinoisenergyprof6878 Unless you can directly convert electricity to thrust, It's not going to pay off. It may make sense for low-altitude low-speed regional applications - I haven't run the numbers, but it's possible that a gas turbine generator running at its most efficient speed with a small amount of battery buffering (to deal with power changes, and such) could be made to work.
My understanding regarding ethanol is that it is only profitable because of subsidies: you put in about 5 barrels of oil worth of fertilizer, refining, and transportation, and you get about 2 barrels of oil worth of energy in ethanol. So the simple answer as to: "what are you going to do with all of that corn?" is "stop growing it because it is a waste of money."
excellent video. Please make more. What % of total energy is jet fuel? What is the cost of biofuel for jets vs petro? Is there a glide path to something that maybe adds $20 to a typical airline ticket?
What about liquid hydrogen? Can power both jet engines and electric fuel cells in a hybrid configuration. Very energy dense. Can be produced renewably without using farmland.
It's energy is 1/3 that of kero by volume when cryo stored as a liquid which has huge weight penalties when considering pressure vessels vs an integral aircraft wing tank.
@@zopEnglandzip Yes I know, but there are new designs with wide delta wings or blended wing body like the Airbus Zero-e BWB to increase tank volume. High pressure tanks aren't required for cryogenic liquid hydrogen, but tank volume is the newest design constraint that can be worked around.
Bigger aircraft use turbofan engines where most of the thrust comes from the ducted fan in the front of the engine. Replacing the core of the turbine engine to drive this fan could be a solution. You did not mention that to burn the fuel you also need oxygen. Luckily there is plenty in the air...
Methane Solid Oxide Fuel Cells provide easily 95% chemical to electrical energy conversion efficiency, compared to at best 60% for jet fuel. For liquefied natural gas that becomes more total available energy. Aluminum-air and aluminum-sulfur batteries can have similar energy density per volume. Using microwave plasma heating instead of combustion to run a jet engine brings many benefits, including not having to worry about the fire going out when designing something which runs supersonic or hypersonic, or switches between modes, and tuning the "combustion" temperature to work with the materials the turbine is made of. These technologies are on the cusp of maturity and will be arriving on the market sooner than people think.
That honestly sounds like tabloid science buzzwording to the finest by piecing together some "cool sounding stuff" without any afterthought. First, natural gas needs to be ignored because of it's inherent nature. It remains a fossil fuel. So basically what you are looking at is "Biogas", and good luck harvesting this to a degree that is required to serve the aviation industry. Might as well put cow-fart capture devices (I'm not kidding, this was actually a thing at least 2 decades ago) for increased methane collection. Only because Al-O and Al-S batteries are the next best thing on paper doesn't mean they are the next best thing in reality. Have you even looked at the manufacturing process? The hazardous waste? The bioproducts? The high maintenance costs due to waste of manufacturing material? Mwave plasma heating does not scale on earth to the requirement in the aviation industry we need due to gravity and air resistence. This is speculative space-design trying to go back to earth and will likely only work for really small scale things. You need Oxygen and ELECTRICITY on board to work for that. We require proportionally more energy to get something in the air that is heavier than being smaller so the question of thrust remains. Okay, fine, so lets put those experimental batteries on there. Oxygen LOVES to go boom. Sulfur LOVES to do other nasty things. And you put those things in an area that is designed to run hot? And how much oxygen is "oxygen" in the plasma heating? Is the oxygen in the air going to be enough? Or do we need oxygen tanks on the jet on top of highly dangerous batteries? I think you havn't done any risk assessment with your statement. How can you say these things are on the cusp of maturity?
@@Khunvyel >without any afterthought You forget that this is how humanity got here in the first place, and it will likely be the way we try to get out of this mess. In Delhi and other large cities in India they are already running cars off CNG and LNG, which will remain the least expensive fuel by energy/mass for the next 25 years or so based on numerous economic projections, generally attributed to natural gas availability from fracking. If I'm not mistaken, some areas of China are trying this as well. In fact if you retrofit your house with solid oxide fuel cells (or really just an efficient enough mechanical generator) instead of solar panels, you can produce electricity for the grid and make a profit continuously, since natural gas is cheaper than electrical energy by a factor of 5 or so in the US, and this is probably similar in most countries at the moment. I have friends and colleagues personally developing Al-S batteries. The electrolyte must be liquid or a gel because aluminum is multivalent, but the deep eutectic solvents involved denature before the battery can go into thermal runaway, and aluminum burns way less readily than lithium. So all the current hype about solid electrolytes with lithium will one day fizzle out, being more a PR move instead of a realistic engineering choice. Aluminum-Sulfur batteries can now do about 1000 charging cycles without significant degradation, with good Coulombic efficiency. Once that reaches 3000 or so, the tech should be competitive with lithium. The limiting factor is the lack of production lines to make this type of battery, which is just a frictional problem and not an engineering fundamental, and it's something I'm working on personally. Aluminum-air batteries do not need on-board oxygen to run: they can be air breathing at cruising altitude. Familiarize yourself with the technology better. as for plasma heating, some researchers in China have a prototype microwave plasma turbojet aip.scitation.org/doi/10.1063/5.0005814 And in the US, the VASIMR project proved years ago that microwave plasma heating could generate very significant thrust. You can bet both countries have a lot more research like this in black projects. It will pop up suddenly from such projects in a decade or so, as a high TRL system already fully engineered. Likely along with better power sources.
would be interesting to see this same video, but looking at the problem from an e-fuels perspective, and see how that compares, ie. hydrogen fuel cell planes, on-board ammonia cracking vs. direct ammonia combustion, e-kerosene for jets, etc. and also the potential for both approaches to complement each other, since there's an overlap in the types of fuels they can produce, eg. producing H2/NH3 from biomethane, or producing methane from methanation of H2 with captured CO2 and going the other way
@@bobthebomb1596 afaik, that can be mitigated by adding extra ammonia post combustion to reduce the NOx back to N2 and H2O in the exhaust stream, or by carefully controlling the ratios of air and ammonia in the combustion but it would be good to have an explanation of the engineering tradeoffs of those options in the video too
I like how you snuck in an F14. Quite relevant too as the US Navy have studied turning the bicarbonates in sea water into synthfuel, though i guess that's more costly that biofuel. But maybe in the future it could work. Mildly disappointing you didn't indulge the molten salt reactor aircraft they USAF tried to develop too haha
I am fairly bullish of hydrogen for air travel despite the draw backs. I would love to see your take on reaction engines and their SSTO plane. They're engine design is clever in it's use of heat and has been proven to work at mach 5.
Fuels like hydrogen or ammonia are too dangerous to use for mass transportation. Hydrogen requires either extreme pressures or cryogenic temperatures, and if it leaks its flammability range is extremely wide. Remember the Hindenburg. An ammonia leak has less explosive potential than hydrogen, but it is much more toxic. It also requires low temperatures or high pressures (although not as extreme as hydrogen in either case) to store in your vehicle. These fuels of the future just cannot compare with the relative safety of having liquid hydrocarbons (at ambient temperatures and pressures) in your fuel tank.
Not just flammability but excitability. Planes are packed full of radio gear, for communications, radar, etc. You can't let stray radio frequency energy near hydrogen, it might get excited and explode.
@@nathanbanks2354 I included ammonia as an example of how you can "store" hydrogen fuel w/o cryogenic temperatures or high pressures. In such a case, being "heavy" is a good thing, it means high storage density.
*"Fossil fuels in the last century reached their extreme prices because of their inherent utility: they pack a great deal of potential energy into an extremely efficient package. If we can but sidestep the 100 million year production process, we can corner this market once again."* -- CEO Nwabudike Morgan _(quote from the computer game "Sid Meier's Alpha Centauri", when your nation discovers the technology "Synthetic Fossil Fuels")_
In terms of liquid biofuels. The carbon source most likely will have to be macro and micro algae, but farmed at the sort of industrial levels we currently use for meat agriculture. You can create nice pumpable feedstocks with them, they use no useful space being out in the ocean, can use salt water, grow incredibly fast, can filter out fertilizer and carbon out of the ocean, process other harmful effluence etc. Then use hydrothermal liquefaction to produce biocrude. Hydrothermal chemsitry is fascinating and likely the source of complex chemistry that started life - but that's another matter. I also like the idea of gasification because it's faster and simpler, then put the methane through a pyrolysis process to release solid carbon black and hydrogen as a form of carbon sequestration.
@George Mann you can use terrestrial biomass, at the expense of biodiversity. You can't have both. We also can't emit any more carbon. We are heading for over 3 degrees. We'll have to go negative, in which case biofuel is over. That's why I said the only sustainable form of flight is trains.
I love this channel. Dispassionate analysis. However, even if we use ethanol to make jet fuel, it's still carbon emissions. Not sure how he avoided that.
Propeller planes can easily travel at 400 MPH, while commercial jets generally fly at around 550 MPH, so not as big a difference as suggested. That being said, battery powered planes are likely to be a niche market for short haul flights. Bio jet fuel does look like the near term solution. Long term, I think there may be a way to use liquid hydrogen and fuel cells. Understand the volume problem, but still think it could be at least a partial answer for mid range flights.
Wouldn't it just be better to go molten salt reactors then use the high heat of the reactor to produce the fuel, from just water(even sea water) and CO2 from the air instead of using farm land in non food production. A side benefit of doing this is the reactors can also make electricity as well so better able to load follow if they are doing both!
I'm very skeptical of the Heart Aerospace project. A 250-mile max. range airliner is abysmal. Keep in mind that every airliner is operated with a safety margin when it comes to range. They always bring more gas than they're gonna need in case they get delayed by weather or other factors (which, if you've traveled even only occasionally, you know happens quite frequently). This means that the Heart Aerospace plane would only be able to service the shortest routes (e.g. JFK to Philly); routes like JFK to DC (about 200 miles in a straight line) are out of reach. I suppose you could make the case for Europe, but there it has to competes with high speed trains. I'd say you need at least double that range to make an electric regional airplane viable.
Dear EnergyProf: you are also an economics professor. Economics and energy consumption are measures of the same thing. All economic activity requires energy consumption, making energy the root cost of everything. The fundamental laws of energy transfer also applies to wealth transfer. Money is data, which is why most of it can be stored and processed by computers. At its root, money is data about energy. The price of gold, or Bitcoin, is proportional to the cost of energy to acquire it. The carbon footprint of any endeavor can be accurately estimated, sans politics, by looking at one number: its price. Taxes are energy suck, and government spending is energy burn. A free market is naturally energy efficient, big government always energy inefficient. In a future video could you please explore the close relationships between energy, politics, and money?
Not really, the four factors of production are land, labor, capital, and entrepreneurship. They are the inputs needed for supply. Increasingly these factors are dominated by skills and intellectual property, the supply is increasingly services, often virtual rather than material. Thus although energy is still very important, particularly for those that don't have it, growth in GDP, particularly in the advanced economies, is being increasingly decoupled from energy consumption.
The future is more efficient and better use of plasma physics. The trick will be to find energy dense molecules that can be stored safely as solid or liquid state, but decompose due to electromagnetic radiation. The light, radio, or magnetic induced decomposition would create high energy bi-products that would otherwise be too unsafe to store without heavy containment. Then you use the high energy bi-products at the instant you create and need them. Put them into a fuel cell or combustion process. The company Plasma Kinetics has a novel approach that may lead to new research areas.
Would love for you to annotate some extra details about Tesla's new tabless 4680 cell. Still a hell of a long way to go even with an evolutionary step, I would imagine. And nobody would predict a revolutionary step in the immediate future.
Although it's a social solution rather than a physics one, another answer is less air travel. The pandemic has shown that a lot of things that were once done in person can be done over the internet. That could eliminate a lot of travel, air or otherwise.
Heavy Theoretically not long, batteries can be charged in 30min. If everything is designed to support that. Heavily depends on energy density of battery. Generally the larger the plane the worse I guess. Once battery energy density improves they could be a viable option for smaller short distance planes.
What about marine transportation? Could cargo be replaced with electricity or return to sail power? Also some of the air travel could be replaced with high speed train which could be electric powered.
New efforts into plasma engines could replace the fuel driven versions. The medium could be natural air driven with high voltages. In space versions they need a gas but in our atmosphere the natural gases could be used??
The other liquid fuel to consider for carbon-free aviation is ammonia; it's basically in-between hydrogen and hydrocarbons in performance. Like hydrogen, it can be made from clean electricity, water, and air; so we can make it with very low environmental impact (much less than biofuel), and it can use any primary energy source (off-peak solar, wind, nuclear, etc). It is much easier to store and transport than liquid or gaseous H2, however, it only has 43% of the energy per unit mass compared to gasoline, so while it will not work for the very long, 6,000 mile trans-Pacific flights, it could work most everywhere else, including the
Sorry, for energy per unit volume, ammonia is between gaseous hydrogen at 5000 psi and hydrocarbons (more relevant as a truck fuel, use energy/mass for airplanes); ammonia has similar energy/volume to liquid hydrogen. For energy per unit mass, nothing is close to liquid hydrogen, but it's hard to deal with.
I think it is fair to say that decarbonized air travel is the highest apple on the decarbonizing tree. Would be far more beneficial to first make sure that the electricity sector is fully nuclearized. Furthermore: Some kind of Fischer Tropsch Jet fuel might be interesting for the US Navy? Since the USN has 12? nuclear powered air craft carriers, these carriers could supply themselves with jet fuel for their planes and with fuel for their non-nuclear escorts, giving it an strategic advantage? You obviously need some place to take the carbon from... 400 ppm CO2 out of the atmosphere wont do it. Maybe from seawater?
I would like to see a video on using other compounds to purify iron without using coke for steel production. I understand we need to reduce the amount of CO², however I find it ridiculous to think we can completely stop emitting CO². Keep in mind that the lack of CO² can be just as bad as too much. I'm not saying that we should do nothing; but I am saying we should seek a middle ground between reducing CO² emissions and trying to stop completely. A plan I would support would be first switching most of our power generation to nuclear power except in areas where hydroelectric, or geothermal are practical. Furthermore we should also be trying to stop cutting down forests to put up wind and solar farms.
Steel and concrete are big contributors. Hydrogen smelted steel is possible. We've got to account for our overproduction of co2 for the last century before we worry about too little.
You may have overlooked, or else I missed, another key benefit of liquid fuels in aircraft vs batteries and that is that as the fuel is burned the aircraft actually gets lighter and easier to propel. The weight of a battery has to be carried regardless of whether it is full or depleted. Great video and thank you
Very good point!
@@illinoisenergyprof6878 remake it
Right and also the jet engine provide electricty for the aircraft, pneumatic power for pressurization/AC system, mechanical energy for the hydraulic systems, and heat for anti icing system making the equations even more dificult for jet electrification
Well there is fuel cells, which with hydrogen cells you’re just producing water as you extract energy so you can just dump it.
Although there is the caveat that it would likely not work for long haul flights as you need altitude, which dumping water out of an aircraft is known to freeze in the air and to the fuselage ; which in order to prevent you mix in an additive to lower the freezing temperature (often a blue liquid I can’t remember the name of), which has the potential to be toxic like standard antifreeze.
On top of potentially altering the chemistry of the fuel cell depending on which point you include the additive I.e in the tank pre-flight or at the exit
Excellent video. Decarbonizing air travel has got to be a much lower priority than doing the easy stuff
Very true. I was just thinking about the hardest part!
In my opinion unless we improve energy density, toxicity, recycling practices, lifespan, and safety factor of current battery technology, followed by charging them with a "clean" power grid, which much of our country does not have, then the "easy" part is not really helping all that much... kind of just keeping the problems of production, mining, toxicity, and emissions in other countries (just like right now) the total resources required to manufacture lithium ion batteries specifically are rarely considered, neither is the 10 year or less average lifespan before complete replacement (usually meaning environmentally terrible but cost saving recycling) along with the fact that petroleum, while not being consumed for energy is still needed for around 15-40% of a modern car's component production (probably higher moving forward)... unless we have a low carbon output power grid already in place and enforce strict requirements on the mining/production/recycling of current technology batteries made in other countries, the North American EV concept/mandates will likely just be another subsidy propped money printer for large corporations without very much positive total environmental impact when viewed as a whole, rather than just concentrating on carbon emissions alone... 🤷♂️ Fun fact one EV passenger car fire often requires 15,000-30,000 gallons of water (Tesla claims 3,000-8,000 in thier first responders guide book) for extinguishing and "tanking" (keeping submerged in a specialty tank) for 24-72 hrs, this water is then highly contaminated with not only standard car fire toxins, but all the highly toxic materials of the battery pack. Typical combustion engine passenger car fires m average around 300 gallons to extinguish, no dunk tank required. If it wasn't for terrorism I feel we could definitely have higher energy density battery packs or even better hydrogen fuel cells on the menu... its hard to use petroleum as a psuedo high explosive, but a 21700 battery with 5x-10x the energy density or all the hydrogen you want at every fuel pump? I think the department of homeland security will be stepping in front of scientific achievement and progress, sadly probably neccesarily 🙁 Thoughts?
Care to list the "easy stuff" Mr. Sophisticated?
@@MadnessMotorcycle Cars. Batteries. Easier not easy. Can be easy
@@rafqueraf but how environmentally friendly is that really... if implemented using current methods and infrastructure? I think people focus too hard on carbon emissions, overlooking the cascading effect of negative environmental impacts 🤷♂️
*see my long winded comment above for a short list of my reservations about widespread EV adoption...
Excellent video! One point I wanted to add not covered in the video was recharge times, when a plane is on the ground airlines want to have it back in the air as quick as possible, refuelling is very quick, but if a plane is sitting for a few hours (I’d guess at least) to charge up its massive batteries, that might severely affect the turnaround time for planes on the ground. Just another thing to think about.
That is a good point. The website for the 19-passenger electric plane I talked about says they can charge it in 40 minutes, and that the charger itself (not the cost of electricity) is $500,000. We'll see of course.
That would be something to see, I wonder what kind of technologies are in use that make it so fast. Seems as fast as a car
Charging time can definitely be solved. Though the power source needed would be huge.
But batteries will remain heavy and not suitable for larger planes and long distances.
@@northsimulation3386 The problem with fast charging is the same on both scales. We see the issue of fast charging smartphones heavily degrading the batteries, and this is the same problem when you charge large quantities of battery cells. I would take a vague guess that this is even more of an issue due to the power requirement to "push" through it. Apart from the degredation, you require more energy for the fast charge, which essentially means it's less efficient due to energy wasted. And we waste already way, WAY too much on simple electric transfer.
Electric energy needs to become far more localized. but we as a general society are not educated enough to have a small nuclear powerplant in the basement of every apartment block.
@@northsimulation3386 Seems to me, each battery cell (18650, 2170, flat pouch, 4680, whatever) has a maximum rate of charge (dependent on capacity, state of charge, and temperature). There's no conceptual reason you can't just charge 10000 cells at the same time, feeding each cell the same power you would feed it if you were only charging 1 cell. In theory it would take the same amount of time.
Of course, nobody actually _does_ charge each cell in parallel. There are physical limits, with the amount of wiring and the amount of charge controller / battery management hardware. So you have to strike a balance. But that doesn't change the _concept_.
The other physical limit is how many kW you can supply to the battery pack. That relates to your grid supply, your cable thickness (or how many charge ports and cables you can use at once), the voltage you're willing to use. This is presumably why the airplane charger is half a million bucks.
As others have noted, the more jet fuel is used the lighter the aircraft gets which makes it more efficient but there's a safety angle as well. If a jet has some kind of emergency and needs to land it can lighten itself by dumping fuel. You see, jets don't really want to land at their max takeoff weight due to the forces involved. It's one thing for a regional aircraft due to the shortness of the flights but long haul and even medium length travel make it difficult.
Only large aircraft have this concern. The 757 has no dump capability and can fly from coast to coast.
@@joecraven2034 but it can burn fuel in holding patterns.
To be fair, planes are this "fragile" because of economical reasons. Basically, they saved weight by reducing structural integrity of the plane to point where it is not safe to land with takeoff load for the sake of efficiency. All I want to say that it is possible to have planes that can carry a battery and still land safely. I however believe that air travel is one of only a few sectors where it is not advisable to go electric. Hence I fully agree with the biofuel points laid out in this video.
@@adrianmartin7344 They are not too fragile to land safely, all commercial jets can land safely at max GTOW.(military may be different) With safety defined as not causing injury to people or other property. The published specified max landing weight is the weight where a safety inspection of the landing gear and specified air-frame components is mandatory following the landing, simply because the forces may have been between the design strength and the ultimate strength.
If a the design load for a normal landing(even a rough normal) is defined as 100% and the required strength safety factor is 150% of design load, then landing at max takeoff weight might have the plane at 115% of design load. Which is less than the desired 50% safety factor but still well below actual design strength, hence the inspection is needed. There may also be simple issues like overheated brakes that need new pads or excess tire tread wear from higher touchdown speed.
They may also reduce fuel load fuel to reduce the stopping distance, even if they could squeeze in they simply want to expend the margin of safety when things are already going wrong. Smaller jets usually already have a short enough landing roll to give plenty of margin even when fully loaded, while a fully loaded longhaul may require the longer runways in a region even under good conditions.
When things are very bad they may want to reduce fuel as a fire hazard unrelated to weight stresses.
@@adrianmartin7344 Planes can carry a battery and still land safely.
It's just batteries will be the only thing they're capable of carrying.
The man, the marker, the legend!
OMG A GRETA FLEW OVER MY HOUSE, SHE WAS SCREAMING "USE THE TRAINS, EAT THE BUGS REEE"
exactly! klaus schwab jugend
"Decarbonizing Air Travel ?"
Answer: Bring back the catapult...
:-)
Professor is always eloquent, informative unt interesting to listén two
For flight specifically, jet fuel is the obvious choice. If we electrify most other things from non-GHG sources, there will be plenty of opportunity to offset, or remove the contribution airplanes make. Nature came up with the stuff, and it's positive properties are orders of magnitude better than anything we could possibly invent. Our combustion machines still have room for improvement, but the fuel, for flight, is aces.
👆this is the correct answer...
I have to agree, this was my conclusion too. If we manage to decarbonize everything except air travel, than thats what we should do. First of it is a small portion of the emissions so we only have a fraction of the problem left, and even that can be handled with carbon capture and sequestration. I'd further say that we could be a lot more optimistic and happy about our position in the fight against climate change if we were at the point by now, where air travel is the most of our concerns.
I came to a similar conclusion for the majority of maritime transport, despite the more feasible non diesel options. To me it makes far more sense to invest in technologies which deliver the largest bang per buck. The "!" (bang) is of course the largest reduction in worldwide carbon dioxide emissions in the shortest time.
Obe big problem with corn->fuel: It is NOT carbon neutral. Hell, Corn->Ethanol is not carbon neutral. Corn doesn't suck up anywhere near enough CO2, especially when you factor in the methods used to convert it.
Where do you think is the carbon in corn coming from?
@@Chupacabras222 What he means is, the resources expended to grow corn end up releasing more carbon than the corn absorbs, and as a result is carbon positive.
@@thesentientneuron6550 I understand. Is it caused mainly by tractors and trucks that run on oil? How significant it is?
@@Chupacabras222 Please refer to this video:
ruclips.net/video/OpEB6hCpIGM/видео.html
I think the implied point of the video is that as the rest of our infrastructure goes electric the farming industry will become more green than it currently is. This might not make corn -> fuel completely carbon neutral, but it should offset it somewhat at least. and would almost certainly be better than what is currently being used no? I mean in the end people are just NOT going to stop flying in significant numbers anytime soon. So finding some kind of more green means to fuel the aircraft industry seems important.
I love that something I first heard of in the original Alpha Centauri Civ game is real and practical. It's a crime that this channel does not have a bajillion views.
Awesome video as always, Prof!
One of my biggest concerns is that here in the UK, electricity is around 15p per kWh and gas is around 3.5p per kWh.
We need to drive this cost way way down before we can move on to everything being electric otherwise our already massive heating bills are going to become literally unaffordable for a lot of people.
The electric car will still likely be cheaper to operate. ICE vehicles are only about 33% efficient, they waste 66% of the energy put into them. A BEV is about 80% efficient, (you lose about 10% at the motor and another 10% on the charge discharge cycle) so it's not as simple as looking at the cost of the energy you are putting into the car, you also have to consider how efficiently it is used. An efficient heat pump is the best way to heat your home with electricity, and often results in much lower energy costs.
@George Mann Don’t natural gas or methanol fuel cells actually extract the hydrogen from those fuels, and in the process produced CO2? You only get zero CO2, when using a fuel, like hydrogen, that has no CO2 in it.
In a similar way to kerosene for transport category aircraft, the legacy investment in natural gas has to be considered. "The Dash for Gas" back in the 1990s looked stupidly short term to me at the time even though I didn't know that Peak Oil and Gas Production from The North Sea would be around 1999/2000.
Did you mean gas as in gasoline or as in natural gas?
Cause gasoline is around 10p per kWh isn't it?
@@TBFSJjunior natural gas that we use to heat our homes.
It started with videos about nuclear reactors 2 years ago. Now I am still here enjoying your videos! Keep up the good work!
Please continue to regularly produce these tutorials. They are very informative, enlightening and appreciated.
Thank you. There are still people who think batteries are the way for air transport, and when they're shown the facts, they hand-wave about 'technology'. Perhaps it would be worth doing some exploration on the physical limits of batteries.
One small comment on propulsion: most commercial 'jets' are in fact turbo-fans, and the jettish part mostly provides energy to drive the great big fan up the front. So they could be electrified, provided a viable energy storage system could be provided for the electric motors. But best in the short term would be a zero-carbon fuel that was a drop-on replacement for existing fuel: does that process you mentioned produce a fuel that can be used without any modifications? Can it be mixed with kerosene (that would be important from a safety angle)?
I love this man
I love planes and this man, today is the best crossover of my life
Thanks Professor! Your videos are of great quality, _consistently_
What I need to know about electric airplanes? How well do they glide?
Whenever there is a discussion about getting rid of fossil fuels in aviation there is nearly always one topic that is overlooked: General Aviation (GA). For those who are not familiar, it's a blanket term that covers everything from Cessnas to Lear Jets. While it is not directly connected to Commercial Aviation (a.k.a. the airline industry) it plays a vital role there because it supplies the industry with all of its pilots.
The GA industry in the US and Canada is so massive that most other countries' airlines outsource their primary pilot training to the US. Meanwhile, GA primary flight instruction in the US remains largely a cottage industry despite the existence of for-profit aviation focused institutions like Embry Riddle. Most of the mom and pop flight schools like the kind that you'd find at your local community airport run on a razor thin profit margin operating aircraft that are often nearly a half a century old.
Approximately 60% of the single-engine piston fleet in the US is comprised of aircraft made before 1980. 20% is composed of mass produced aircraft made after 1980 and the other 20% are amateur built kit aircraft that are intended for personal use and are prohibited form being rented out for flight instruction by FAA regulations (the FFA, on the other hand, has not released any official guidance on these aircraft). This means that unlike the US automotive or airline fleets, the US single-engine piston fleet that teaches nearly the entire world how to fly is not going to simply phase out the vast bulk of its old aviation fuel airplanes after 20 years in favor of new ethanol kerosene or electric models.
Modifying the current ones may be technically possible, but it is economically unfeasible as modifying anything on a type certificated airplane comes with massive costs. Performing an engine swap can cost several thousand dollars just in labor costs while the engines themselves may costs many tens of thousands of dollars, even on a half century old airplane. Meanwhile, new airplanes can costs many hundreds of thousands of dollars. The reasons behind the age of the current GA fleet are many but, as you can see, cost is one of the reasons. This is why the flight training industry in the US still uses these old airplanes.
Any significant change in cost to the GA fleet could lead to a near total collapse of the flight training industry in the US and could turn the pilot shortage situation that currently exists in the airline industry into a crisis. I'm not sure how to solve this issue, but its something that virtually nobody who talks about decarbonizing air transportation even mentions.
Peter, don't forget US commercial aviation gets a substantial number of pilots from the military.
@@brownro214 Not anywhere near enough to satiate demand, though. And the military uses civilian piston-engine aircraft for initial flight training, anyway.
Not really an issue, future airliners won't have pilots and be a lot safer as no scope for pilot error.
Corn-based Ethanol doesn't really seem like such a great approach to me, mostly due to a combination of two main reasons: 1) The ethanol fuel energy balance is just kinda bad for corn ethanol, and 2) Land use. It sort of feels like it defeats the purpose. Corn ethanol's biggest advantage seems to be that it has a huge incumbency advantage, so to speak. Lots of investment in it and a lot of political clout to go along with that.
Sugar beets are a much better alternative.
I suppose the biggest reason corn based ethanol is so relevant here is not that it is the best crop to produce ethanol, but because the land used for that corn, likely, has no immediately better use. (ie in the US there is a lot of corn land that doesn't have much else competing for the space)
Sugar cane ethanol for example is much more efficient in some senses, but can only be grown in certain areas. I imagine many competing crops would be the same, as well as any other way of synthesizing/creating a fuel. More of a complex optimization problem than simple efficiency, though of course the results can always change. And there may be plug and play improvements the real professionals are considering
I preemptively thumbs-up’d you before watching video. Wasn’t disappointed. Keep up the good work
Hi bypass ratio turbo-fans, the types of jet engines that power commercial aircraft, develop around 90% of their thrust via the primary compressor, so the actual exhaust of the burning fuel only provides around 10%. Turning one of these primary compressors via an electric engine is, therefore, theoretically possible, but the rest of your arguments remain valid. Thanks prof!
David- thanks for another informative and hopeful video. I love your clear, complete, evidence based explanations.
Good video! One note, the latest battery from Tesla is the 4680. It's not in commercial use yet but will be by the end of this year.
thanks Prof! I took your energy class a couple years back, and really enjoyed it. I've been missing new video's.
Professor I think you might have missed some crucial points in the simplification:
1) Most of the energy used in the Industrial sector isn't electricity for a reason, we cannot electrify steel making, iron ore processing, concrete and cement. All of these require carbon-based inputs. The biggest outputs of our civilization: Steel, Concrete, Cement and Plastics cannot be made out of electrons, they come from coal, coke, oil, nat gas etc. The only part we could electrify is some of the heat generation processes in those heavy industries, and only part of it.
2) In transportation, one of the main uses of diesel is in heavy machinery (trucks, tractors etc) which cannot be electrified, and the same goes for Shipping, the driver of global economy and commerce. Shipping will have to rely on diesel (until possibly hydrogen comes into the picture in some decades).
A big chunk of the industrial and transportation sectors will remain fossil-fuel based.
As a UKsian my principal focus is a "killing two birds with one stone" approach, destroying the radioactive artefacts we have stored at Sellafield by fission and producing process heat for industrial applications.
What about synthetic fuels made from carbon capture ?
I've legitimately considered becoming an Illini because of the prof.
Recently found this gem of a channel.
Great video, as always.
Awesome shirt :)
Yay thank you for another great video lesson, I have been waiting for ages for another release.
You overlooked ammonia. It can be burned directly in a turbojet if you don't mind the nitrous oxides, but can be easily split by catalyst to burn hydrogen only.
OK but what is the size and weight of your catalytic converter to be fitted on an airplane?
The is the possibility of what our navy blue is looking into. That is the production of jet fuel from sea water. This involves extraction of C0² from ocean water and attaching the H to the carbon and dumping the O² into the air. Takes a certain amount of energy to do this but nuclear reactors have this in abundance. So far the best way to get the weight a volume unless some sort of nuclear reactor is used. Reactors would have the added benefit of eliminating all pathogens during flight.
7:38- "You can do it..."
I'll believe it when I see it.
Noticed he didn't say how much that plane costs, for the garbage performance it will be outlandishly expensive too.
Loved it. Your explanation of fusion could be a game changer. Just going to be some years away.
Love your videos Prof. Ruzic! What is the net Carbon impact of using corn to produce ethanol fuel then burning that fuel? Is it zero because the Corn plants extract carbon from the atmosphere to produce the corn? I assume there is carbon currently because of the tractors and trucks used in production are probably hydrocarbon based, but if they could be electrified would it be net zero? Or does carbon leak into the system some other way?
You have it right. If the other farm inputs were also carbon-neutral, then the biofuels would be very close to carbon-neutral too.
Thanks for the talk and all the given numbers
good video. I like your style. reminds me of being back in school again. I like that. would watch more like this.
Airbus did a test with liquid hydrogen, and found that the whole fuselage is needed to be filled in order to cross the Atlantic
Batteries are simply not for airplanes; they are too heavy and do not have near the same density as kerosene or more accurately,(jet fuel). There is simply no near-future replacement.
Fuels also are required by the FAA to have certain lubercating properties, but more importantly, flash points. Natilural gas has not been proven to burn at the same temps as jet fuel, while having similar viscosity, Ect.
Batteries are also double bad because unlike fuel, the weigh the same regardless of energy state; a empty fuel tank has 10% fuel (unburnable) but a empty battery weighs 100% of it's full mass.
Have you looked into carbon engineering's fuels? They are made from sequestered co2 from the air. I often wonder about pairing one of their plants with nuclear power. One of their processes requires a temperature of 900c. Which might be too hot to heat up directly with nuclear heat. But they could do a two stage system where it's mostly heated using nuclear thermal, and the rest by using an electric process. A plant could be built close enough to an airport to reduce shipping costs also.
This is the obvious solution and it's what the world will inevitably converge to over time as reality and physics ultimately wins over ideology and beliefs.
I often wonder about synthetic methane fuels from sequestered CO2, but I don't know how practical or economic it is.
@@bobthebomb1596 One thing's for sure - it is better than dedicated biofuels. As for how exactly it will qualify vs. everything else... we'll see.
@@zolikoff I agree, as world population continues to grow we will likely require that land for growing food.
Synthetic methane is certainly possible, Musk intends to use the method to provide fuel for a return trip from Mars. I just wonder if it could be produced in sufficient quantity and at a competitive price, to replace fossil fuels for combustion engines.
@@bobthebomb1596 it's hard to say as it's new technology. Carbon Engineering lowered the price of sequestered CO2 by using off the shelf water tower (cooling tower?) components. So they got to use the economics of scale somewhat. The material they use for the carbon capture I believe would need that as well. I could be wrong about the details here, but that's the general idea. How it's powered I imagine is a big component in price.
This is a good analysis. I'm concerned about biofuels displacing farmland used to feed people, but I didn't know the US already produces enough ethanol for air travel. In the long term, it's probably easier to make new jet engines that can burn ethanol directly or farms could produce biodiesel, though according to the chart at 3:15 the energy per weight isn't as good. I'm also hoping direct carbon capture companies like Carbon Engineering become cost competitive. The technology works, but it could remain too expensive.
Ammonia could work for container ships. It's twice as heavy as jet fuel, it's liquid at around 8 bar, and can be produced using electrolysis instead of stripping hydrocarbons. Maersk is already exploring this.
Hey, I just discovered your channel. This stuff is really neat, thank you for putting it out there!
It looks like Liquid Hydrogen requires more volume than jet fuel but is lighter weight seems like that could be a realistic option to keep the turbine engine design I've seen that GE is building hydrogen turbine engines for electricity production. I've also read that that it could be done with Ammonia which could be a cheaper fuel source.
Probably depends on how that table accounts for storage weight. If the larger tanks required push the actual number up, it's basically dead on arrival for larger planes.
Also embrittlement is gonna carry a cost on the fuel systems, but not like that'll stop anyone. Might Concorde a model or two.
Love your videos, Professor. Thank you.
I'd be really interested in a followup video on using something like Hydrogen as a fuel. I think it meets a lot of the challenges you've raised.
The problem with hydrogen is that you need energy to make it. Converting methane to it is the easiest, but why not just use the methane then.
@@illinoisenergyprof6878 Also storage tanks of compressed hydrogen are heavy. I think the weight of tanks in hydrogen cars is an several times the weight of the hydrogen it can store. And then you've got a plane at higher altitudes so the pressure ratios will be even more intense.
Airships! My man!!! Can’t forget the LTA
We remember airships: R38, R101, Shenandoah, Akron, Macon, Hindenburg...
Any airship capable of carrying a serious useful load is so large that the weather at one end is different than the weather at the other, and sooner or later, nature tears it apart.
Trans Atlantic/Pacific electric Ecranoplan's.
You'd have to figure out what to put in them, right? Hydrogen is ... problematic. Helium ... I suspect we'd run low on the global supply of helium pretty darned quickly.
They only have very niche uses today because of that, the speed and lift limits and the gas limitations, but man they are still so cool.
Here's to the engineer that someday convinces his boss that an airship is the right vehicle for some crazy job.
Prof makes me think of giants like Feynman and Sagan sometimes in the way he takes incredibly complex subjects and makes them engaging and accessible to the layperson.
I love these videos, always informative, I just wish more people watched them :)
If only we could get our various governments to understand the concept of energy density so precisely articulated in this video!
best channel on youtube
Thank you very much for these videos. I have been subscribed for some time now and It makes my day to see a new video. No matter what one’s belief is concerning climate change, or politics, we as a race are responsible to be a good custodian of our planet. Your videos often address solutions that would make us as a people more efficient and better as caretakers. It’s not controversial to want to make the “world a better place.”
One thing you have overlooked (or omitted for simplicity sake) is that jet engines are the least efficient engines. The engines used in cargo aircraft are high-bypass turbofan which derive the vast majority (approx 80%) of their thrust from the first stage, and only a minor part from the air passing through the core.
Yep. You stole my thunder but your comment is spot on.
I agree -- and tried to make that point at 6:54
Rocket engines are the least efficient engines.
I have been checking the comments to see if anyone commented about ducted fans. I believe the idea being proposed for electrifying planes is to have a motor drive a ducted fan, ie. the jet engine core is replaced with a motor. So the speed of the plane shouldn't be impacted, as it would be if propellers were used, as suggested.
Using electric motors has the benefit of not having to waste energy on the compressor stages and lost energy in the hot fast moving turbine exhaust gases.
However, I wonder what the size and weight of the electric motor required will be. Jet engines for planes aren't measured in shaft power, but the GE Frame 9 used industrially for turning generators, compressors etc. has a shaft power of 132MW. I don't know how close in size it is to the jet engine core on a plane, but the equivalent motor is going to be pretty big.
Some points to add to the comparison with Teslas AA battery.
Their small size multiplied by the number we need adds up to a big ammount of weight and volume. It would be better to compare with industrial grade battery racks.
Fuel pipes and pumps are also quite heavy in aircrafts.
But one big big advantage of fuel is that once it's burnt the weight is out. Most airliner planes cannot land with the same weight they took off with.
There are 2 important aspects missed on your analysis.
1 - Lapcat from REL inc (UK), using the SABRE engine. An air breathing rocket engine with LH2 as the fuel. Flight at Mach 5.5 / 80-90k ft altitude. Hydrogen can be easily produced from H2O either using nuclear heat or electrolysis. Proposed aircraft is ultra long range capable, even London or LA to Australia non stop possible.
2 - Electric Fan like engines powering high subsonic or even supersonic aircraft. Fossil engines are very limited to how much O² you can scoop from the atmosphere. But electric Fan engines are NOT limited by how much oxygen is available at cruising altitudes. Full power available even at 70000ft where the air is super thin. As long as enough lift can be produced a LOT of the downsides from heavier/bulkier batteries can be offset. Not enough to fly long haul routes, but enough to fly perhaps routes up to 2000 to 3000km, which encompasses more than half of the current air travel fuel consumption. Lithium cell technology is far from its ultimate limits while Jet fuel isn't going to get anymore energy dense. Expect at least a doubling of energy density both by weigh and volume improvement over the next decade. For instance the Tesla tabless 4680 design improves on the 2170 by at least 25%.
Elon Musk stated that current Lithium energy density (from a few years ago) was insufficient to make compelling electric transport aircraft but that a doubling of energy density from Tesla Model S era 18650 (or a 50% improvement from 4680) would be enough to start making compelling air transport.
The other very significant possibility is since electric engines are much lighter than big fossil turbofans, its viable to design a vertical take off / landing aircraft, which fully eliminates the need for flaps/slats and wing designs that must produce enough lift at lower indicated airspeed. This allows to design wings that only produce enough lift for climb/cruise at higher indicated airspeeds which reduce drag some more.
If we electrify all ground transportation and short sea and air transportation then the biofuels we make are enough to cover the rest, long haul flights, transoceanic shipping and helicopters. We "only" need like 3 times more electricity than we have today but that is doable over a couple of decades.
Large ships could realistically be nuclear powered in the future.
@@N330AA Having enough guards on board to prevent the risk of hijacking and potential nuclear terrorism might make that economically non-viable. But of course technically it works as US aircraft carriers and Russian ice breakers shows. Probably better to have the nuclear reactor on land making some sort of carbon neutral fuel for ships.
@@zapfanzapfan Yeah good point.
These videos really show that engineers know what to do, there just isn't anyone paying them to take us there. I have a patent pending for an electric car smart charging method that allows EVs to act as long term energy storage. I know everyone talks about it all the time and everyone knows it's the future, but nobody has bothered to develop it yet. It's so ripe for development I was able to take it to the next level in my free time.
Are you aware that Tesla is doing this as we speak?
@@GtDowns source?
@@AlexWaardenburg teslamotorsclub.com/tmc/threads/arbitrage-with-power-wall.156157/ look up EV Arbitrage. On the introduction of the 2022 Ford F150 Lightning (EV), they state multiple times that if your pickup is charged up and you get a power outage at your home, the battery in your EV could possibly power your house for a few days.
Hi !
I'd also like to believe that electrification is the path to decarbonization but the lack of investment in nuclear power by western countries is very worrying and seems incompatible with an increase in electricity demand.
Thanks from France.
You French have been building half of the Champagne region full of wind mills for the last couple of years. Very usefull, given the fact what 80% is nuclear, and a reactor can't be switched of due to xenon poissoning.
Thanks EU.
We will get the reckoning in 15 years when all those wind turbines and solar panels go down and the waste material need to be disposed of. I bet the developed nations will just dump the waste to developing nations like what they did with the plastic recycling scam.
I seem to recall that there were concepts in the 1950’s for nuclear powered aircraft propulsion systems. Now the appetite for nuclear power in transportation systems is largely limited to military budgets, but all the same - nothing else has more energy density! Therefore it must be worth exploring the idea a little in the name of decarbonisation.
So the most obvious question is, can you do it, and make the contamination risk inherently safe in the event of a catastrophic air accident? The previous discussions about pebble bed reactors were interesting. If the fissile material is contained inside glass pebbles and these pebbles can withstand the forces involved in an air accident, maybe the mop up exercise afterwards is made much easier.
A bit off-topic perhaps, but it would have been nice to see some discussion of rail travel as an alternative to aviation on short to mid length overland routes. Rail is easy to electrify and travel speeds are competitive with short range flights.
Prof, thanks for making this video. Provides great insight into what can be achieved with electrification. I am wondering though about ethanol based fuels. These are produced more cleanly, but while burning them, don't you produce the same amount of CO2 anyhow? Also converting these bio types from food to fuel comes at an energy cost. You can electrify the systems that runs the conversion, but no matter what, unless there is some breakthrough in battery tech that decreases the weight significantly, while increasing the weight per unit energy, air travel will have to be done with fuels, or make air travel so expensive, only the rich can afford it.
On another note, how about hydrogen fuel cell tech for air travel? Is this not safe as regular kerosene, or costs too much to mass produce?
Never mind. Should have seen the table/graph you provided at around 2:50. It says cooled liquid hydrogen is a quarter of the energy output of jet fuel. Unless this is not the same, but I doubt it.
the thing about corn based ethanol is that, well it comes from corn. The way that the corn actually grows is by taking all the carbon it needs from the air and thus, when you burn the fuel, the carbon in the air is not any higher than it was earlier.
Might have been overlooked or maybe I missed it, with fuel, you only have to carry one component of the reaction. Air is always available and exhaust is dumped overboard.
Oh Boy here I go again learn something very cool
The best way to decarbonize air travel is replacing most short haul flights with high speed rail and leave long haul alone. Unfortunately that's a tall order for USA but Europe and Asia are well suited for that transition.
Ironically flights in within Europe are often cheaper and much faster than rail. High speed rail might be a good alternative to cars. For example: $82 and 2.5 hours to get from Barcelona to Prague by plane vs $240 and 24 hours by rail?
What about a hybrid electric jet fuel system for commercial jets. Could this be implemented to feasibly mitigate jet fuel consumption?
Yes. Using jet fuel to take off and climb, then electricity to cruise would certainly save energy. You don't get all the way, but hybrids, like with cars, do get you part way there.
@@illinoisenergyprof6878 Unless you can directly convert electricity to thrust, It's not going to pay off.
It may make sense for low-altitude low-speed regional applications - I haven't run the numbers, but it's possible that a gas turbine generator running at its most efficient speed with a small amount of battery buffering (to deal with power changes, and such) could be made to work.
Your channel is just amazing !!
Thank you for the detailed video prof!
Your stuff is amazing. So clearly explained.
My understanding regarding ethanol is that it is only profitable because of subsidies: you put in about 5 barrels of oil worth of fertilizer, refining, and transportation, and you get about 2 barrels of oil worth of energy in ethanol. So the simple answer as to: "what are you going to do with all of that corn?" is "stop growing it because it is a waste of money."
excellent video. Please make more. What % of total energy is jet fuel? What is the cost of biofuel for jets vs petro? Is there a glide path to something that maybe adds $20 to a typical airline ticket?
Sorry, asked my questions at about 8min in. Tkx again for the interesting video. What is your lab working on?
What about liquid hydrogen? Can power both jet engines and electric fuel cells in a hybrid configuration. Very energy dense. Can be produced renewably without using farmland.
It's energy is 1/3 that of kero by volume when cryo stored as a liquid which has huge weight penalties when considering pressure vessels vs an integral aircraft wing tank.
@@zopEnglandzip Yes I know, but there are new designs with wide delta wings or blended wing body like the Airbus Zero-e BWB to increase tank volume. High pressure tanks aren't required for cryogenic liquid hydrogen, but tank volume is the newest design constraint that can be worked around.
Bigger aircraft use turbofan engines where most of the thrust comes from the ducted fan in the front of the engine. Replacing the core of the turbine engine to drive this fan could be a solution.
You did not mention that to burn the fuel you also need oxygen. Luckily there is plenty in the air...
Methane Solid Oxide Fuel Cells provide easily 95% chemical to electrical energy conversion efficiency, compared to at best 60% for jet fuel. For liquefied natural gas that becomes more total available energy. Aluminum-air and aluminum-sulfur batteries can have similar energy density per volume. Using microwave plasma heating instead of combustion to run a jet engine brings many benefits, including not having to worry about the fire going out when designing something which runs supersonic or hypersonic, or switches between modes, and tuning the "combustion" temperature to work with the materials the turbine is made of. These technologies are on the cusp of maturity and will be arriving on the market sooner than people think.
That honestly sounds like tabloid science buzzwording to the finest by piecing together some "cool sounding stuff" without any afterthought.
First, natural gas needs to be ignored because of it's inherent nature. It remains a fossil fuel. So basically what you are looking at is "Biogas", and good luck harvesting this to a degree that is required to serve the aviation industry. Might as well put cow-fart capture devices (I'm not kidding, this was actually a thing at least 2 decades ago) for increased methane collection.
Only because Al-O and Al-S batteries are the next best thing on paper doesn't mean they are the next best thing in reality. Have you even looked at the manufacturing process? The hazardous waste? The bioproducts? The high maintenance costs due to waste of manufacturing material?
Mwave plasma heating does not scale on earth to the requirement in the aviation industry we need due to gravity and air resistence. This is speculative space-design trying to go back to earth and will likely only work for really small scale things. You need Oxygen and ELECTRICITY on board to work for that. We require proportionally more energy to get something in the air that is heavier than being smaller so the question of thrust remains. Okay, fine, so lets put those experimental batteries on there. Oxygen LOVES to go boom. Sulfur LOVES to do other nasty things. And you put those things in an area that is designed to run hot? And how much oxygen is "oxygen" in the plasma heating? Is the oxygen in the air going to be enough? Or do we need oxygen tanks on the jet on top of highly dangerous batteries? I think you havn't done any risk assessment with your statement.
How can you say these things are on the cusp of maturity?
@@Khunvyel
>without any afterthought
You forget that this is how humanity got here in the first place, and it will likely be the way we try to get out of this mess.
In Delhi and other large cities in India they are already running cars off CNG and LNG, which will remain the least expensive fuel by energy/mass for the next 25 years or so based on numerous economic projections, generally attributed to natural gas availability from fracking. If I'm not mistaken, some areas of China are trying this as well. In fact if you retrofit your house with solid oxide fuel cells (or really just an efficient enough mechanical generator) instead of solar panels, you can produce electricity for the grid and make a profit continuously, since natural gas is cheaper than electrical energy by a factor of 5 or so in the US, and this is probably similar in most countries at the moment.
I have friends and colleagues personally developing Al-S batteries. The electrolyte must be liquid or a gel because aluminum is multivalent, but the deep eutectic solvents involved denature before the battery can go into thermal runaway, and aluminum burns way less readily than lithium. So all the current hype about solid electrolytes with lithium will one day fizzle out, being more a PR move instead of a realistic engineering choice. Aluminum-Sulfur batteries can now do about 1000 charging cycles without significant degradation, with good Coulombic efficiency. Once that reaches 3000 or so, the tech should be competitive with lithium. The limiting factor is the lack of production lines to make this type of battery, which is just a frictional problem and not an engineering fundamental, and it's something I'm working on personally.
Aluminum-air batteries do not need on-board oxygen to run: they can be air breathing at cruising altitude. Familiarize yourself with the technology better.
as for plasma heating, some researchers in China have a prototype microwave plasma turbojet aip.scitation.org/doi/10.1063/5.0005814
And in the US, the VASIMR project proved years ago that microwave plasma heating could generate very significant thrust.
You can bet both countries have a lot more research like this in black projects. It will pop up suddenly from such projects in a decade or so, as a high TRL system already fully engineered. Likely along with better power sources.
would be interesting to see this same video, but looking at the problem from an e-fuels perspective, and see how that compares, ie. hydrogen fuel cell planes, on-board ammonia cracking vs. direct ammonia combustion, e-kerosene for jets, etc.
and also the potential for both approaches to complement each other, since there's an overlap in the types of fuels they can produce, eg. producing H2/NH3 from biomethane, or producing methane from methanation of H2 with captured CO2 and going the other way
Direct ammonia combustion sounds like a non starter due to the NOx emissions.
@@bobthebomb1596 afaik, that can be mitigated by adding extra ammonia post combustion to reduce the NOx back to N2 and H2O in the exhaust stream, or by carefully controlling the ratios of air and ammonia in the combustion
but it would be good to have an explanation of the engineering tradeoffs of those options in the video too
@@DjChronokun Interesting.
I like how you snuck in an F14. Quite relevant too as the US Navy have studied turning the bicarbonates in sea water into synthfuel, though i guess that's more costly that biofuel. But maybe in the future it could work.
Mildly disappointing you didn't indulge the molten salt reactor aircraft they USAF tried to develop too haha
I love these videos, but how much Petrochemicals are used to grow corn? How much energy to turn a corn cob into jet fuel? How energy sense is it?
I am fairly bullish of hydrogen for air travel despite the draw backs.
I would love to see your take on reaction engines and their SSTO plane. They're engine design is clever in it's use of heat and has been proven to work at mach 5.
Fuels like hydrogen or ammonia are too dangerous to use for mass transportation.
Hydrogen requires either extreme pressures or cryogenic temperatures, and if it leaks its flammability range is extremely wide. Remember the Hindenburg.
An ammonia leak has less explosive potential than hydrogen, but it is much more toxic. It also requires low temperatures or high pressures (although not as extreme as hydrogen in either case) to store in your vehicle.
These fuels of the future just cannot compare with the relative safety of having liquid hydrocarbons (at ambient temperatures and pressures) in your fuel tank.
Not just flammability but excitability. Planes are packed full of radio gear, for communications, radar, etc. You can't let stray radio frequency energy near hydrogen, it might get excited and explode.
Ammonia is twice as heavy as jet fuel, but I still think liquid hydrogen could work.
@@nathanbanks2354 I included ammonia as an example of how you can "store" hydrogen fuel w/o cryogenic temperatures or high pressures. In such a case, being "heavy" is a good thing, it means high storage density.
What about a hybrid approach with electric and jet? Maybe in runway DC contacts for take off power.
*"Fossil fuels in the last century reached their extreme prices because of their inherent utility: they pack a great deal of potential energy into an extremely efficient package. If we can but sidestep the 100 million year production process, we can corner this market once again."*
-- CEO Nwabudike Morgan
_(quote from the computer game "Sid Meier's Alpha Centauri", when your nation discovers the technology "Synthetic Fossil Fuels")_
In terms of liquid biofuels. The carbon source most likely will have to be macro and micro algae, but farmed at the sort of industrial levels we currently use for meat agriculture. You can create nice pumpable feedstocks with them, they use no useful space being out in the ocean, can use salt water, grow incredibly fast, can filter out fertilizer and carbon out of the ocean, process other harmful effluence etc. Then use hydrothermal liquefaction to produce biocrude. Hydrothermal chemsitry is fascinating and likely the source of complex chemistry that started life - but that's another matter. I also like the idea of gasification because it's faster and simpler, then put the methane through a pyrolysis process to release solid carbon black and hydrogen as a form of carbon sequestration.
@George Mann you can use terrestrial biomass, at the expense of biodiversity. You can't have both. We also can't emit any more carbon. We are heading for over 3 degrees. We'll have to go negative, in which case biofuel is over. That's why I said the only sustainable form of flight is trains.
@George Mann Finland will be carbon neutral by 2035, probably negative soon after. So it can be done.
@George Mann they don't actually. Helsinki is not using any biomass. Other cities are swiftly following.
Carbon isn't really harming us. If it was, environmentalists wouldn't have private jets
Carbon is great, it's the source of all life after all.
Another great video Prof. Would be awesome to see you do some talks about nuclear powered aircraft or spacecraft.
Nuclear powered aircraft is a dangerous concept. Look at america now, 4 general aviation accidents in as many days.
I love this channel. Dispassionate analysis.
However, even if we use ethanol to make jet fuel, it's still carbon emissions.
Not sure how he avoided that.
Propeller planes can easily travel at 400 MPH, while commercial jets generally fly at around 550 MPH, so not as big a difference as suggested. That being said, battery powered planes are likely to be a niche market for short haul flights. Bio jet fuel does look like the near term solution. Long term, I think there may be a way to use liquid hydrogen and fuel cells. Understand the volume problem, but still think it could be at least a partial answer for mid range flights.
Wouldn't it just be better to go molten salt reactors then use the high heat of the reactor to produce the fuel, from just water(even sea water) and CO2 from the air instead of using farm land in non food production. A side benefit of doing this is the reactors can also make electricity as well so better able to load follow if they are doing both!
Exactly.
I'm very skeptical of the Heart Aerospace project. A 250-mile max. range airliner is abysmal. Keep in mind that every airliner is operated with a safety margin when it comes to range. They always bring more gas than they're gonna need in case they get delayed by weather or other factors (which, if you've traveled even only occasionally, you know happens quite frequently). This means that the Heart Aerospace plane would only be able to service the shortest routes (e.g. JFK to Philly); routes like JFK to DC (about 200 miles in a straight line) are out of reach. I suppose you could make the case for Europe, but there it has to competes with high speed trains. I'd say you need at least double that range to make an electric regional airplane viable.
Dear EnergyProf: you are also an economics professor. Economics and energy consumption are measures of the same thing. All economic activity requires energy consumption, making energy the root cost of everything. The fundamental laws of energy transfer also applies to wealth transfer. Money is data, which is why most of it can be stored and processed by computers. At its root, money is data about energy. The price of gold, or Bitcoin, is proportional to the cost of energy to acquire it. The carbon footprint of any endeavor can be accurately estimated, sans politics, by looking at one number: its price. Taxes are energy suck, and government spending is energy burn. A free market is naturally energy efficient, big government always energy inefficient. In a future video could you please explore the close relationships between energy, politics, and money?
Not really, the four factors of production are land, labor, capital, and entrepreneurship. They are the inputs needed for supply.
Increasingly these factors are dominated by skills and intellectual property, the supply is increasingly services, often virtual rather than material.
Thus although energy is still very important, particularly for those that don't have it, growth in GDP, particularly in the advanced economies, is being increasingly decoupled from energy consumption.
The future is more efficient and better use of plasma physics. The trick will be to find energy dense molecules that can be stored safely as solid or liquid state, but decompose due to electromagnetic radiation. The light, radio, or magnetic induced decomposition would create high energy bi-products that would otherwise be too unsafe to store without heavy containment. Then you use the high energy bi-products at the instant you create and need them. Put them into a fuel cell or combustion process. The company Plasma Kinetics has a novel approach that may lead to new research areas.
The FFA part had to be the most perfect freudian slip. 10:27
Please. More videos.
Would love for you to annotate some extra details about Tesla's new tabless 4680 cell. Still a hell of a long way to go even with an evolutionary step, I would imagine. And nobody would predict a revolutionary step in the immediate future.
Nothings better then having an unlicensed gas engine on your back with a wing made out of nylon.
That’s flying.
Not so useful for crossing the Atlantic.
Could you do an episode on atmospheric carbon extractors?
Although it's a social solution rather than a physics one, another answer is less air travel. The pandemic has shown that a lot of things that were once done in person can be done over the internet. That could eliminate a lot of travel, air or otherwise.
How heavy are the batteries?
How long does it take to recharge those batteries?
What's the range?
Heavy
Theoretically not long, batteries can be charged in 30min. If everything is designed to support that.
Heavily depends on energy density of battery. Generally the larger the plane the worse I guess.
Once battery energy density improves they could be a viable option for smaller short distance planes.
What about marine transportation? Could cargo be replaced with electricity or return to sail power?
Also some of the air travel could be replaced with high speed train which could be electric powered.
FYI - the newest Tesla battery is the 4680. The 2170's are still in use too.
Great Video
New efforts into plasma engines could replace the fuel driven versions. The medium could be natural air driven with high voltages. In space versions they need a gas but in our atmosphere the natural gases could be used??
Take SMRs, build Planes around it, let them fly autonomous for freight. Still a lot faster then ship. How to get prices low enough?
The other liquid fuel to consider for carbon-free aviation is ammonia; it's basically in-between hydrogen and hydrocarbons in performance. Like hydrogen, it can be made from clean electricity, water, and air; so we can make it with very low environmental impact (much less than biofuel), and it can use any primary energy source (off-peak solar, wind, nuclear, etc).
It is much easier to store and transport than liquid or gaseous H2, however, it only has 43% of the energy per unit mass compared to gasoline, so while it will not work for the very long, 6,000 mile trans-Pacific flights, it could work most everywhere else, including the
Sorry, for energy per unit volume, ammonia is between gaseous hydrogen at 5000 psi and hydrocarbons (more relevant as a truck fuel, use energy/mass for airplanes); ammonia has similar energy/volume to liquid hydrogen. For energy per unit mass, nothing is close to liquid hydrogen, but it's hard to deal with.
I think it is fair to say that decarbonized air travel is the highest apple on the decarbonizing tree. Would be far more beneficial to first make sure that the electricity sector is fully nuclearized.
Furthermore: Some kind of Fischer Tropsch Jet fuel might be interesting for the US Navy? Since the USN has 12? nuclear powered air craft carriers, these carriers could supply themselves with jet fuel for their planes and with fuel for their non-nuclear escorts, giving it an strategic advantage? You obviously need some place to take the carbon from... 400 ppm CO2 out of the atmosphere wont do it. Maybe from seawater?
www.navy.mil/DesktopModules/ArticleCS/Print.aspx?PortalId=1&ModuleId=523&Article=2259523
I would like to see a video on using other compounds to purify iron without using coke for steel production. I understand we need to reduce the amount of CO², however I find it ridiculous to think we can completely stop emitting CO². Keep in mind that the lack of CO² can be just as bad as too much. I'm not saying that we should do nothing; but I am saying we should seek a middle ground between reducing CO² emissions and trying to stop completely. A plan I would support would be first switching most of our power generation to nuclear power except in areas where hydroelectric, or geothermal are practical. Furthermore we should also be trying to stop cutting down forests to put up wind and solar farms.
Steel and concrete are big contributors.
Hydrogen smelted steel is possible.
We've got to account for our overproduction of co2 for the last century before we worry about too little.