Toyota's Developing A Hydrogen Combustion Engine!

hello everyone and welcome in this video we're going to talk about the work toyota is doing on developing hydrogen combustion engines so the idea is what if instead of making a whole bunch of new electric cars we instead took the combustion cars that we already have built and converted them to hydrogen-based fuels and so instead of using a carbon-based fuel which has carbon emissions you would have a hydrogen-based fuel which just has water as its emission so you would eliminate those carbon emissions now that sounds like it would make a lot of automotive enthusiasts pretty happy so what toyota did is they created a corolla sport that was powered by a hydrogen combustion engine and they entered it into a 24-hour endurance race and so this is powered by a 1.6 liter turbocharged inline three cylinder that comes from the gr yaris and then it's been converted over to run on hydrogen now it's not nearly as simple as saying it's been converted over to run on hydrogen it's quite a process in fact back in 2016 they were still using a 50 50 mix of gasoline and hydrogen because it's very difficult to get it to run on hydrogen alone but here we are five years later and they have a functional hydrogen combustion engine so this engine operates much like a typical gasoline engine it has four strokes intake compression power exhaust has direct injection for the hydrogen fuel and it is spark ignited so in comes oxygen you spray in hydrogen and then your emissions are water so how do they do in that 24 hour race well the results are less than ideal but i think keep in mind you know it's proof of concept vehicle really that's going out there so in the 24 hour race uh they were able to travel 1634 kilometers about a thousand miles in 24 hours so not super far uh 12 total hours of driving four total hours of refueling they had to refuel 35 times which gives them an average refueling speed of about seven minutes so seven minutes is a decent amount of time to refuel though compared to of course an electric car uh significantly quicker to refuel and then eight hours of time spent repairing the vehicle from things that had broken and doing safety checks to make sure it was safe running around out there these hydrogen tanks are storing that hydrogen compressed hydrogen at about 10 000 psi 700 bar now we need to discuss emissions because it's not quite as simple as you take oxygen and hydrogen and then out comes water so of course air has nitrogen in it as well and because your combustion temperatures within a hydrogen engine are high you do actually have nitrogen oxides forming so that's one of the harmful emissions that you're creating and then the other is actually co2 so where does this co2 come from well your engine oil so it's a small amount you have engine oil underneath and that oil can come in through the pcv system positive crankcase ventilation system or it can come through as blow-by and be burned within that combustion chamber and then you're going to have those carbon emissions so i thought you know it's worth figuring out exactly how much might that be so let's say you have a car that burns a quart of oil every three thousand miles and my fellow enthusiasts of old hondas and subarus you know what this life is like um i've lived it many times so we're burning one quart of oil every 3000 miles motor oil is about 85 carbon and it weighs about eight pounds for a gallon of it and then the molecule a molecule of co2 is a carbon with two oxygens looking at their atomic weights 12 are carbon 16 for oxygen so for every pound of carbon that you burn well then you have about 3.7 pounds of co2 produced because that carbon is you know 12 40 fourths of that full molecule that comes out that co2 molecule so if we multiply all of that across we can figure out in 3 000 miles how much carbon might we how much co2 might we emit into the atmosphere if we're burning one quart which is a good amount every 3000 miles just 6.2 pounds now let's give some context here so let's say we drive 200 000 miles with this vehicle uh burning oil at that rate well then that gives us a total amount of co2 emitted 413 pounds over 200 000 miles now compare that to the typical gasoline engine that's about 160 000 pounds of carbon emissions using you know an average of 25 mpg so in comparison we're at just point two six percent so obviously even if you were burning a lot of oil uh you know the the amount of carbon emissions is almost negligible in comparison to a gasoline engine so from a co2 standpoint these are great okay so co2 isn't a big deal how about nitrogen oxide so i found a study that looked at various methods that you could have a hydrogen combustion engine without much nitrogen oxide emissions one of those methods is hcci homogeneous charge compression ignition where you have well mixed hydrogen and air and actually hydrogen diffuses really quickly so that's easy to do even with direct injection easy to do from a mixture standpoint hcci itself is actually very difficult to do but you have compression ignition in this case and the good news is if you were able to achieve this it's very lean combustion so you don't have much nitrogen oxides about one part per million so you know a hundred times better than today's diesel engines and then from a thermal efficiency standpoint these are at about 45 thermal efficiency which is fantastic now what's the bad news well hcci is very difficult to do it's why we don't have production example engines of hcci in cars today very difficult to control i saw a study that was saying you would need in order to have a cold start in an hcci hydrogen engine you need a compression ratio of 42 to 1. pretty wild and then another really big bad piece of news for hcci uh engines hydrogen engines as they would only have 25 percent of the load capability versus a gas engine meaning one-fourth the power so you need it to be really large engine if you wanted a significant amount of power so some big challenges with hcci hydrogen engines another solution what if you just use spark ignition and poor fuel injection a couple challenges here the good news is you don't really have nitrogen oxide emissions assuming you operate at stoichiometric air fuel ratio with hydrogen and the oxygen and you use a three-way catalytic converter so you've got your port injection it's spark ignited uh the bad news is it's not as efficient as hcci you know peak efficiency is around 38 um the other bad news knock and pre-ignition are a big problem with hydrogen engines uh because the ignition energy required for hydrogen is very low it's very easy to ignite a hydrogen oxygen mixture and then also hydrogens have a problem with backfiring if you have port ignition so that intake valve hydrogen has a very small quench distance and what that means is hydrogen combustion can travel through a very small crevice so if you have your intake port slightly open the hydrogen combustion could work its way back into the intake where you're spraying that fuel in so what's a potential solution to that well you use direct injection so you don't have to worry about fuel in the intake like toyota is doing and then another problem with this spark ignition poor fuel injection engine is that load so it's about 50 percent uh that of a gas engine so better than our hcci but we're still only making half the power of a similar sized gas engine so in that case well how do you overcome the power discrepancy well use a turbocharger just like toyota is doing all right so these hydrogen combustion engines are sounding pretty promising so why isn't it more common why isn't it more popular why don't we see it today well unfortunately there are a lot of very real problems so let's start off with the fuel itself and that fuels production so hydrogen fuel production there's many ways to produce hydrogen fuel many of them end up being worse from an emissions standpoint than just using gasoline or diesel and so then it's like well what's the point today about 95 percent of hydrogen production is done by using natural gas reforming and there's minimal to no you know emissions co2 emission benefit of doing so i found studies that are on you know both sides of the fence but basically if you're using natural gas to create that hydrogen then you're not really benefiting from a carbon standpoint and so again it's like well why do it and so then you would have to go to you know low carbon energy sources in order to create that hydrogen using electrolysis and so the the problem with doing so is that natural gas reforming is very cheap and so it's very expensive to produce hydrogen using you know renewable resources which is what toyota did for this 24-hour race for the sourcing of that fuel they used green hydrogen but it's very expensive so that's the problem it could be two to four times the cost per kilogram purchasing that fuel uh versus if it had come from natural gas and you need lots of energy to produce that hydrogen as a simple summary i was reading a technical report by the joint research center of the european commission it was 148 pages on well to wheel energy analysis which yes is as boring as it sounds but there was a quote i found a bit entertaining turning usable electricity into hydrogen is unlikely to make sense from a global energy or greenhouse gas point of view not great all right so next we get to consumption so the efficiency of a hydrogen combustion engine once you get to the wheels you start with that hydrogen in the tank once you get to the wheels you might have something like a 25 efficiency so is there perhaps a more efficient way to turn that hydrogen into useful work into moving your car and yeah and it just so happens that toyota happens to make that vehicle a toyota mirai a fuel cell is a much much more efficient way of you know moving a vehicle and so in this case you know you might have 50 percent efficiency at the wheels using a vehicle like the toyota mirai which uses a fuel cell instead of hydrogen combustion so both of them using hydrogen as the fuel source uh but the mirai is significantly more efficient you're not going to have you know the loud combustion noises and excitement associated with it but you're able to go twice as far on the same amount of fuel so you know you only need half the energy to travel a certain distance and there's very few scenarios uh where a fuel cell would not win simply based on that alone so if you know a company was going to invest in it they would invest in the one that gets way more useful work out of it now in racing perhaps uh where expensive fuel is fine you know they're already paying a lot for racing fuels uh and in racing where you want these sounds uh you know hydrogen combustion could make sense in that scenario but from you know a consumer standpoint it's going to make much more sense to make vehicles as fuel cells versus hydrogen combustion now if there were an easy way to convert existing engines that would be great but unfortunately toyota found out that it's not simple at all in trying to convert you know their 1.6 liter urs grs engine for this corolla to hydrogen they had quite a bit of reliability problems so you know it's kind of a new engine at the end of the day it's not something that just existed off the shelf and then they put hydrogen injectors on it and then suddenly just worked on hydrogen so it's very difficult to do that conversion all right so you might say well jason i don't care that fuel is going to be significantly more expensive and i don't care that the vehicle is going to be inefficient i want my combustion engine well there's still yet another problem so storage is an issue with hydrogen so they have these really high pressure tanks and the reason they have these really high pressure tanks is to increase the energy density of the fuel itself but even at 10 000 psi this compressed hydrogen has an energy density of 1.3 kilowatt hours per liter that's at 700 bar 10 000 psi versus e10 uh ethanol 10 gasoline in the united states that's about 9 kilowatt hours per liter so a seven times difference in storage size if you want the same amount of energy you know relative for a combustion engine so you're going to have these massive uh storage tanks for the fuel they have to be really you know heavy duty strong in order to have this really high pressure hydrogen and so you know from a fuel cell standpoint versus a combustion engine standpoint you're gonna need two times uh the tank size in order to compensate for that lack of efficiency so you know if you go back to the first gen toyota mirai which had a range of about 300 miles it had about 200 pounds of fuel tanks so these are really heavy too they're massive they take up a lot of space in the car and then on top of that they're really heavy so if you want the same range you either have 400 pounds of tanks or you cut your range in half and you have the same weight um so pretty impractical right and so that was the case with this race car as well they had no rear visibility because the back of the car was all taken up by these massive hydrogen tanks they take up a lot of space and so that kills the practicality of the car and so what you want is to reduce the size of that tank and the way you're able to do that is by using a hydrogen fuel cell which means you need half the size uh rather than double the size uh for that fuel tank so hydrogen combustion requiring two times the energy two times the cost of fuel massive impractical storage tanks uh they're gonna be heavy vehicles uh and then you know you're still gonna have emissions on top of that where you don't have those emissions guaranteed when you're using the fuel cell so very real challenges that do exist with hydrogen combustion nonetheless it does seem pretty cool and it does seem like it could be a cool application in motorsport so thank you all so much for watching and if you have any questions or comments feel free to leave them below

Channel: Engineering Explained

Views: 1,954,739

Keywords: hydrogen, combustion, internal combustion engine, hydrogen combustion, toyota, engineering explained, toyota mirai, hydrogen fuel cell, fuel cell

Id: 3IPR50-soNA

Length: 14min 6sec (846 seconds)

Published: Wed Jun 16 2021

Reddit Comments

[u/Balenabros]

Let’s go hysr

[u/beenett1]

The very first problem he lists is the current production (limitations) of hydrogen.

[u/OutdoorsyHiker]

So cool!