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.
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.
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
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.
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.
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.
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 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.
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.
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.
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.
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.
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.
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.
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.
Regarding the energy density graph at around the 3 minute mark: I noticed LNG, while a lower energy density than kerosene, is better than ethanol in both specific energy and energy density. What about Methane from Electrolysis and the Sabatier process, compressed to a green equivalent of LNG? Would the weight of cryo-storage outweigh the inherent benefits? Water electrolysis and the Sabatier process would introduce a lot of losses, but so does growing corn. Last I looked, the energy turnaround from corn to ethanol was still being argued, but hovering around 1.3.
Good points. While LNG is close on the graphs, but I am not sure if that includes the pressure tanks. Making methane from a non-carbon source is also possible, and I think this is one examples of the other ways to make "green" liquid fuels.
@@illinoisenergyprof6878 On the topic of making "green" liquid fuels, would you please consider doing one or or a couple videos related on pathways to synthetic fuels (for example, syngas production from coal/biomass, the Sabatier reaction, the Fischer-Tropsch process, etc.)? I always enjoy watching your videos. :)
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?
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.
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??
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
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.
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)?
Doesn’t ethanol have serious environmental costs as well especially given amount of land needed to grow the ethanol? Is it more efficient than say growing algae in tanks and using that as a biofuel instead?
My main question, what would it take to go all Electric vehicles, as governments introduce laws mandating it. How much theoretical electrical grid capacity would need to be added, how would generation scale down to local grids
One good thing about electric vehicles is that they could be charged at night when there is low demand on the grid. This helps, but does not fully alleviate the issue. We would eventually need more infrastructure and more generating capacity.
The only reason I ask is you always see “articles on Facebook” don’t fully believe them. But the load requirements change depending on line voltages. If my understanding and conversions are some what correct. 20 amp (5 kw) car on a 240 volt breaker should be around 1 amp on a 4150 v supply voltage at the power line. So amperage wise there could be lots of room for addition. The constant would be 5kw added to the generation station. Or am I way wrong in my thinking
@@timothytorpy4837 There's the capacity of your house circuits, but I suspect most homes have plenty of that. 200A breaker boxes are standard in newer houses, I gather, and charging usually happens at night when the AC is doing less work. More of concern is the grid capacity writ large. As the prof notes, there's currently a lot of excess capacity at night (for the same reason: nobody's running their AC as hard), so this may not be a big deal. Though if the grid moved to a ton of solar, nighttime energy availability could become more of an issue.
@@ps.2 absolutely I don’t know about the USA as I’m Canadian. Older homes had 80 amp service. Standard now here from my knowledge is 100 to 150. Either way shouldn’t be a huge issue if managing services. Mine was geared too the story’s that out system isn’t built for EV vehicles with out massive investment
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.
One relevant point, your graph didn't have ammonia. Recent work has been done on using ammonia in jets and diesel engines (including ships) And ammonia production from renewables and hydrolysis or from biological production is advancing. One unrelated question. I noticed that wind and solar production as a percentage of US electricity is much higher than percentage of consumption. Do wind and solar have a higher system loss rate?
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.
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.”
Is it infeasible to put a smaller battery (and maybe a supercapacitor) on the plane and charge it in flight from the ground with lasers shot at the wing? And maybe do this at the airport, supplying energy during takeoff and climb. Maybe have batteries enough to go 100 miles between recharges?
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.
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.
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.
I have to wonder whether this bio kerosene still produces CO2 when it is burned, and if so, what is the benefit? Unless of course you are using the furphy of carbon credits from growing the Corn to offset that CO2
Corn become corn because it takes CO2 out of the air. When you burn it, you put the CO2 back. That is why it is carbon neutral. Of course it is not exactly, because you have to do other things through the process, but generally that is the idea.
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.
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.
I am currently watching the video, and it may be mentioned in the video. Question: Is bioethanol a viable fuel for a turbine engine? Does it burn hot enough to make an efficent fuel?
IEP, Does Your Hydrogen Energy Density Figures include Hydrogen with Pure Oxygen or does it Represent Hydrogen with Air (Nitrogen,Oxygen etc)?. Good Report.
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...
@@illinoisenergyprof6878 and here I thought all physics professors were infallible. I guess just the ones I had at Ohio State. Still love your vids, thanks for making them!
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.
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.
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.
Shouldn't energy density be adjusted for efficiency? Like jet fuel is only 50% efficient in a commercial jet engine. So a 10x increase in density is really only like 5x because 1/2 of the energy will be lost to unused heat.
Look at the table again. It has much lower energy density then jet fuel per volume. So you would have to have ridiculously huge tanks of hydrogen on board.
The density of hydrogen is extremely low and it like to leak right through metal containers. So H2 tanks have to be quite large and heavy thereby eliminating any perceived benefits.
A fair point. Consider this though: already 40% of corn produced is going to ethanol production. If the ground transportation sector is electrified, then that ethanol can go to air travel instead, so maybe we're not tripling or quadrupling the amount of corn we need to produce. Also something to consider - the plants grown for biofuel will absorb CO2 from the atmosphere - so a plane running on 100% biofuel will have its fuel emissions completely offset by growing plants for the biofuel. Last point: while the carbon impact of farming is certainly not negligible, it's probably much less of a pollution source than current methods of refining and burning conventional crude oil.
How is ethanol made non-hydroscopic or is it? Its awfully important for your liquid fuel to not freeze at altitude and be a pure fuel source at least in a aircrafts piston engine. Do turbines just not care?
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!
Excellent video as usual. However I was surprised there was no mention of Hydrogen fuel cells. And forgive my cynicism but Illinois is in corn country right? I think the ethanol idea is a good one though that needs to be studied. It is certainly a fuel that would adapt easily to air travel. But isn't the exhaust part carbon? I'm not a chemist and don't know the answer. While the price of oil is a big part of the question, an even bigger and more important consideration is what burning that oil does to our climate and what the climate does to life on earth. As for deicing while airborne, heating elements on leading edges is not a deal breaker. Inflatable boots are also a possibility and are used extensively in general aviation today.
The idea about using biofuels is that growing the corn takes the CO2 out of the air, so it is ok to put it back in when it is burned. You are right about Illinois being corn country. My house is surrounded by corn fields so I see and think about it every day!
There are a few problems with hydrogen: It's low energy per unit volume, so you need bigger fuel tanks, and therefore a bigger plane. It's a Cryogenic fuel, so you need insulation or refrigeration, and you have to take off immediately after fueling so it doesn't boil off. If your flight gets delayed you have to detank all your fuel. Hydrogen is mostly made from fossil fuels anyway. You can make it by using green energy to electrolyze water, but we need infrastructure for that, and it may be more expensive. Hydrogen molecules (H2) are very small and so they tend to slowly leak out of nearly any container. None of these problems are insurmountable, however. It may be beneficial to use hydrogen fuel in the future, especially when fossil fuels start to run out.
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!
What I need to know about electric airplanes? How well do they glide?
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:
ua-cam.com/video/OpEB6hCpIGM/v-deo.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 preemptively thumbs-up’d you before watching video. Wasn’t disappointed. Keep up the good work
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
Thanks Professor! Your videos are of great quality, _consistently_
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.
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.
It started with videos about nuclear reactors 2 years ago. Now I am still here enjoying your videos! Keep up the good work!
Recently found this gem of a channel.
Great video, as always.
Awesome shirt :)
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.
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.
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?
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.
Professor is always eloquent, informative unt interesting to listén two
OMG A GRETA FLEW OVER MY HOUSE, SHE WAS SCREAMING "USE THE TRAINS, EAT THE BUGS REEE"
exactly! klaus schwab jugend
David- thanks for another informative and hopeful video. I love your clear, complete, evidence based explanations.
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.
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.
What about a hybrid approach with electric and jet? Maybe in runway DC contacts for take off power.
thanks Prof! I took your energy class a couple years back, and really enjoyed it. I've been missing new video's.
Hey, I just discovered your channel. This stuff is really neat, thank you for putting it out there!
good video. I like your style. reminds me of being back in school again. I like that. would watch more like this.
Thanks for the talk and all the given numbers
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.
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.
What about synthetic fuels made from carbon capture ?
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.
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?
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.
Yay thank you for another great video lesson, I have been waiting for ages for another release.
I've legitimately considered becoming an Illini because of the prof.
"Decarbonizing Air Travel ?"
Answer: Bring back the catapult...
:-)
14:06 that IS an interesting graph. Where is RP1? I gots ta know.
Regarding the energy density graph at around the 3 minute mark: I noticed LNG, while a lower energy density than kerosene, is better than ethanol in both specific energy and energy density. What about Methane from Electrolysis and the Sabatier process, compressed to a green equivalent of LNG? Would the weight of cryo-storage outweigh the inherent benefits? Water electrolysis and the Sabatier process would introduce a lot of losses, but so does growing corn. Last I looked, the energy turnaround from corn to ethanol was still being argued, but hovering around 1.3.
Good points. While LNG is close on the graphs, but I am not sure if that includes the pressure tanks. Making methane from a non-carbon source is also possible, and I think this is one examples of the other ways to make "green" liquid fuels.
@@illinoisenergyprof6878 On the topic of making "green" liquid fuels, would you please consider doing one or or a couple videos related on pathways to synthetic fuels (for example, syngas production from coal/biomass, the Sabatier reaction, the Fischer-Tropsch process, etc.)? I always enjoy watching your videos. :)
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.
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?
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.
I love this man
I love planes and this man, today is the best crossover of my life
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??
Loved it. Your explanation of fusion could be a game changer. Just going to be some years away.
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.
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.
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.
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)?
Doesn’t ethanol have serious environmental costs as well especially given amount of land needed to grow the ethanol? Is it more efficient than say growing algae in tanks and using that as a biofuel instead?
Why can't we use ethanol or biodiesel directly (instead of converting it to jet A1) in jet turbines with some burner modifications ?
I love these videos, always informative, I just wish more people watched them :)
What about modular nuclear powered flight? How does the power density of solid fuel compare to jet fuel?
My main question, what would it take to go all Electric vehicles, as governments introduce laws mandating it. How much theoretical electrical grid capacity would need to be added, how would generation scale down to local grids
One good thing about electric vehicles is that they could be charged at night when there is low demand on the grid. This helps, but does not fully alleviate the issue. We would eventually need more infrastructure and more generating capacity.
The only reason I ask is you always see “articles on Facebook” don’t fully believe them. But the load requirements change depending on line voltages. If my understanding and conversions are some what correct. 20 amp (5 kw) car on a 240 volt breaker should be around 1 amp on a 4150 v supply voltage at the power line.
So amperage wise there could be lots of room for addition. The constant would be 5kw added to the generation station.
Or am I way wrong in my thinking
@@timothytorpy4837 There's the capacity of your house circuits, but I suspect most homes have plenty of that. 200A breaker boxes are standard in newer houses, I gather, and charging usually happens at night when the AC is doing less work.
More of concern is the grid capacity writ large. As the prof notes, there's currently a lot of excess capacity at night (for the same reason: nobody's running their AC as hard), so this may not be a big deal. Though if the grid moved to a ton of solar, nighttime energy availability could become more of an issue.
@@ps.2 absolutely I don’t know about the USA as I’m Canadian. Older homes had 80 amp service. Standard now here from my knowledge is 100 to 150. Either way shouldn’t be a huge issue if managing services. Mine was geared too the story’s that out system isn’t built for EV vehicles with out massive investment
Could you do an episode on atmospheric carbon extractors?
Sir can you make a video on SOLAR DOME?
Take SMRs, build Planes around it, let them fly autonomous for freight. Still a lot faster then ship. How to get prices low enough?
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.
One relevant point, your graph didn't have ammonia. Recent work has been done on using ammonia in jets and diesel engines (including ships)
And ammonia production from renewables and hydrolysis or from biological production is advancing.
One unrelated question. I noticed that wind and solar production as a percentage of US electricity is much higher than percentage of consumption. Do wind and solar have a higher system loss rate?
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.
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.”
Please continue to regularly produce these tutorials. They are very informative, enlightening and appreciated.
Is Carbon Capture tech viable, because won't ethanol eat up tons of farmland that might be better used in the future for feeding people?
Is it infeasible to put a smaller battery (and maybe a supercapacitor) on the plane and charge it in flight from the ground with lasers shot at the wing? And maybe do this at the airport, supplying energy during takeoff and climb. Maybe have batteries enough to go 100 miles between recharges?
See now I'm picturing KC-130 tankers but instead of a jet fuel proboscis it's a CCS-2 plug on the end of a cable.
Dear Professor, what are your thoughts on Airbus's ZeroE hydrogen turbine planes?
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.
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.
I wonder which is safer? Separate battery for each engine? Slow and steady...
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.
I have to wonder whether this bio kerosene still produces CO2 when it is burned, and if so, what is the benefit? Unless of course you are using the furphy of carbon credits from growing the Corn to offset that CO2
Corn become corn because it takes CO2 out of the air. When you burn it, you put the CO2 back. That is why it is carbon neutral. Of course it is not exactly, because you have to do other things through the process, but generally that is the idea.
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.
best channel on youtube
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.
I am currently watching the video, and it may be mentioned in the video.
Question: Is bioethanol a viable fuel for a turbine engine? Does it burn hot enough to make an efficent fuel?
Watch to the end of the video...
Ammonia made using heat or electrical power from nuclear power plants? Green?
Your channel is just amazing !!
wait. Doesn't the burning of Ethanol still produce carbon?
It is common in the US to write Watt hours as Whr? I am asking because the short for hour is h not hr.
IEP, Does Your Hydrogen Energy Density Figures include Hydrogen with Pure Oxygen or does it Represent Hydrogen with Air (Nitrogen,Oxygen etc)?.
Good Report.
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...
Your stuff is amazing. So clearly explained.
@10:41 I'm not sure I want the Future Farmers of America certifying aviation fuels. Maybe you meant FAA?
Indeed. My error and apologies!
@@illinoisenergyprof6878 and here I thought all physics professors were infallible. I guess just the ones I had at Ohio State.
Still love your vids, thanks for making them!
Thank you for the detailed video prof!
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 wonder how much would the plane ticket cost if you simply include the CO2 extraction from the atmosphere as an extra service?
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.
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.
Shouldn't energy density be adjusted for efficiency? Like jet fuel is only 50% efficient in a commercial jet engine. So a 10x increase in density is really only like 5x because 1/2 of the energy will be lost to unused heat.
Hi, really interesting video again!
I just wondering what about the H2 to use with the air planes, it could be worth it even for long flights, right?
Look at the table again. It has much lower energy density then jet fuel per volume. So you would have to have ridiculously huge tanks of hydrogen on board.
The density of hydrogen is extremely low and it like to leak right through metal containers. So H2 tanks have to be quite large and heavy thereby eliminating any perceived benefits.
Ok, I see thank you for the answers.
What about the environmental impact of growing so much corn? By the time it is converted to fuel, most of the damage has already been done.
one thing we need to look at though is whether biomass ethanol is in fact "decarbonized"... farming is not exactly carbon neutral...
A fair point. Consider this though: already 40% of corn produced is going to ethanol production. If the ground transportation sector is electrified, then that ethanol can go to air travel instead, so maybe we're not tripling or quadrupling the amount of corn we need to produce. Also something to consider - the plants grown for biofuel will absorb CO2 from the atmosphere - so a plane running on 100% biofuel will have its fuel emissions completely offset by growing plants for the biofuel. Last point: while the carbon impact of farming is certainly not negligible, it's probably much less of a pollution source than current methods of refining and burning conventional crude oil.
Please. More videos.
What about the Tesla 4680 battery and SSD batteries
How is ethanol made non-hydroscopic or is it? Its awfully important for your liquid fuel to not freeze at altitude and be a pure fuel source at least in a aircrafts piston engine. Do turbines just not care?
Oh Boy here I go again learn something very cool
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!
This is happening already, several airlines are flying on what their calling RJET or renewable Jet.
Excellent video as usual. However I was surprised there was no mention of Hydrogen fuel cells. And forgive my cynicism but Illinois is in corn country right? I think the ethanol idea is a good one though that needs to be studied. It is certainly a fuel that would adapt easily to air travel. But isn't the exhaust part carbon? I'm not a chemist and don't know the answer. While the price of oil is a big part of the question, an even bigger and more important consideration is what burning that oil does to our climate and what the climate does to life on earth. As for deicing while airborne, heating elements on leading edges is not a deal breaker. Inflatable boots are also a possibility and are used extensively in general aviation today.
The idea about using biofuels is that growing the corn takes the CO2 out of the air, so it is ok to put it back in when it is burned. You are right about Illinois being corn country. My house is surrounded by corn fields so I see and think about it every day!
@@illinoisenergyprof6878 Good point. Thanks for the reply and keep making these videos. I've learned a lot from them.
How about green Hydrogen and fuel cells to power aircraft and ships too for that matter?
There are a few problems with hydrogen:
It's low energy per unit volume, so you need bigger fuel tanks, and therefore a bigger plane.
It's a Cryogenic fuel, so you need insulation or refrigeration, and you have to take off immediately after fueling so it doesn't boil off. If your flight gets delayed you have to detank all your fuel.
Hydrogen is mostly made from fossil fuels anyway. You can make it by using green energy to electrolyze water, but we need infrastructure for that, and it may be more expensive.
Hydrogen molecules (H2) are very small and so they tend to slowly leak out of nearly any container.
None of these problems are insurmountable, however. It may be beneficial to use hydrogen fuel in the future, especially when fossil fuels start to run out.