[viernullvier]

This looks like a solution in search of a problem. Hydrogen combustion will never reach the efficiency of current off-the-shelf fuel cells, let alone potential future improvements on fuel cells; battery-level efficiency is completely out of the question. There is no use case for choosing combustion instead of fuel cells, period. Hydrogen combustion introduces additional problems like NOx emissions that simply don't exist for fuel cells. Aside from maybe material science, there are no further insights to be gained here that would be applicable in any real-world scenario/product.

> But using a hydrogen engine rather than fuel cells would have certain advantages. Such vehicles would employ conventional engine technology and provide a driving experience similar to gasoline cars. And "it's easy to generate torque at low rpms, making it ideal for trucks," a Toyota executive said.

None of these are advantages, it's rather the opposite of an advantage. Electric motors provide consistent torque from zero to maximum RPM and don't need sophisticated transmissions. On top of that, hydrogen engines don't work particularly well with variable loads (the same goes for fuel cells, but this can be mitigated by a buffer battery).

Fun fact: Toyota's car isn't even the first hydrogen-powered car to complete a 24h race. In 2013, a modified Aston Martin Rapide S equipped with a dual-fuel petrol/hydrogen system completed the 24 Hours of Nürburgring.

[Hypx_]

It has the advantage of allowing us to avoid investing in any new manufacturing facilities or new production lines. For some cases, it makes sense.

[perl4ever]

I'd like to know what the advantage is of burning hydrogen compared to just making synthetic hydrocarbon fuel.

I believe it usually uses fossil fuel feedstock but doesn't have to.

[femto]

Lower pollutants [1].

I can't see how burning hydrogen in an engine will compete though, as an electric car is mechanically simpler than a car with an internal combustion engine. As economies of scale build, cars powered by electric motors will undercut internal combustion engines in price and reliability.

[1] https://afdc.energy.gov/fuels/hydrogen_benefits.html

[perl4ever]

Hybrids are the future; convince me I'm wrong.

No matter how refined the manufacture of electric cars gets, a hybrid will always reduce the battery capacity needed to a fraction of what it would be otherwise. I believe the typical difference between a plug-in hybrid and full electric is around an order of magnitude.

It is just as irrational to have a battery with a 300 mile capacity as it is to have a gas engine with 300 hp. In either case, you are allowing for the greatest possible need which happens rarely if at all. A hybrid allows you to build both the engine and the battery for the average case which is on the order of 10% of the worst case. This is a huge inherent benefit.

[bobthepanda]

Where are we currently producing any hydrogen fuel in large enough quantities? Or hydrogen fuel tanks?

The engines are not the hard part of the hydrogen car.

[Hypx_]

Electrolysis of water. We'll have more than enough.

[mateo1]

Electric motors might produce consistent torque but that torque isn't as high as you need for a truck. Certainly not without a transmission. Fuel cells might be more efficient than ICEs but you ignore power to weight ratios, performance degradation and total useful life. Also there's the total cost of the vehicle to consider. Personally I dislike both hydrogen and electric vehicles on the grounds of safety. 50kg of hydrogen will produce a pretty devastating explosion in seconds. You've seen teslas burn so you know that side too. At this moment the only thing we gain by converting conventional vehicles to electric or hydrogen is less local NOx and particulate emissions and offsetting them with more emissions elsewhere. These technologies would make a lot more sense if we could source cheap electricity from renewable sources, and we don't. Wind and solar make up an impressive 11% of total electricity production in the US but if you account for storage requirements we're still decades away from anything resembling the dreams of a low carbon economy. It's consumers and pop-sci that's driving this change, and that's not necessarily a good thing.

[DarmokJalad1701]

> You've seen teslas burn so you know that side too.

How often do Teslas burn compared to ICE cars?

> At this moment the only thing we gain by converting conventional vehicles to electric or hydrogen is less local NOx and particulate emissions and offsetting them with more emissions elsewhere.

Using an EV with today's grid is still significantly more efficient in terms of energy use and CO2 emissions even with some fossil fuels being used to power the grid.

Source: https://www.fueleconomy.gov/feg/Find.do?year=2020&vehicleId=...

A few large heat engines (power plants) running at a constant peak-efficiency load is much more efficient than thousands of smaller heat engines running at variable loads.

[mateo1]

Actually I bothered calculating the CO2 emissions per mile for a 2021 diesel car with 88mpg nominal efficiency with the same factor (1.25) as this website and it turns out to just 145 grams of CO2/mile. Compared to Tesla's nominal 130g/mile on grid mix, the diesel car is just 11% higher than the electric car. Pretty impressive eh? It's also at least $30,000 cheaper (not accounting subsidies you see), has a longer lifespan and range, doesn't require overhauling the global electrical grid infrastructure with a cost of untold billions, doesn't have all the externalities of the car battery lifecycle and sourcing lithium, and I'm pretty sure it produces less CO2 per mile when you're driving in cold weather and the cabin needs heating. So even if your target is lowering CO2 emissions there are better ways to spend all this capital for doing so. Or at least that's my opinion.

[nickik]

All of this is basically wrong.

> Certainly not without a transmission.

If you have 6 wheels and you can put an engine on each one there is zero reason what so ever to suggest you can't get enough torque.

And if you look at the Tesla Semi you will see that it leaves every other truck in the dust while fully loaded.

> Also there's the total cost of the vehicle to consider.

All indications of electric drive show far better total lifecycle cost then any ICE has shown. I don't know about fuel cells but I don't think hydorgen in any form will have much of a market.

> You've seen teslas burn so you know that side too.

Any state will tell you that they burn far less often then any other car. And even when they do it almost always not an instant fire but a slowly developing thing.

And we are still at the infancy of battery tech, there are already much more advanced suppression systems being tested both for the pack and the cell.

On pack level you can look at Tesla structural packs (that will be in the Semi too) and on the cell level there are Soteria.

In 5-10 years getting an EV to burn will be borderline impossible.

> These technologies would make a lot more sense if we could source cheap electricity from renewable sources, and we don't.

All over the world they already do. Most EV load at night and can profit from cheap base line energy that is often nuclear or access wind.

And even if its not zero-carbon power now, if the truck/car has a lifetime of 15 years it will be increasingly more carbon efficient over time.

And additionally even with coal power its better to drive EV.

> It's consumers and pop-sci that's driving this change, and that's not necessarily a good thing.

Not its the fact that electric cars and trucks are simply better and more practical in many ways. The lifetime cost are considerably better.

The cost curve for solar and wind is still collapsing and its idiotic to wait to switch to substantial transport only when you reach some % of the energy source you want. Because from that point on it takes 30+ years to make the transition.

You have to do both at the same time, anything else makes no sense what so ever.

[pelorat]

> Electric motors might produce consistent torque but that torque isn't as high as you need for a truck

Sounds like that could be solved by having additional motors that can be switched on by demand, plus a gearbox.

[Johnythree]

> Electric motors might produce consistent torque but that torque isn't as high as you need for a truck.

This makes no sense. To get more torque, just use a larger motor.

For the same weight, electric motors can produce much more torque than an ICE.