[GJim]

> Hydrogen has its place in our energy economy

It certainly does not! (At least, not in any meaningful sense).

A) How do you store it?

Hydrogen does not compress to a liquid (except a cryogenic temperatures), meaning storage requires bulky, heavy and dangerous high pressure storage..... or cryo kit.

B) Where do you get the hydrogen from?

Electrolysis of water gives less hydrogen energy out than electrical energy you put in.... its more efficient to use the electrical energy directly. Currently we obtain hydrogen from natural gas, which itself is a finite resource (not to mention CO2 is emitted when extracting the hydrogen from gas).

Seriously, the sums don't add up and hydrogen is a looser however you look at it. The only people promoting it here are the natural gas industry who are looking to get money pushing the "hydrogen economy" vapourware.

[dismalaf]

> Electrolysis of water gives less hydrogen energy out than electrical energy you put in....

This is literally all energy storage... Lithium-ion batteries lose about 10-20% during charging and another 5% during discharge.

How do you figure any energy storage medium would give you more than 100% of the energy you put into it?

[ggreer]

The efficiency of using electricity to split water, then compressing and transporting the hydrogen, then using that hydrogen in a fuel cell to power an electric motor, is much worse than using electricity to charge a battery to power an electric motor.

Also electricity is available almost everywhere. Hydrogen is only available at a few specialized fueling stations.

[dismalaf]

Electrolysis is actually around 80% efficient. The main issue is infrastructure, you're right about that.

But the comment I initially responded to said there's energy loss as though that's not the case with literally every type of energy storage.

[ggreer]

Splitting water is only one step in getting electricity to move a hydrogen fuel cell vehicle's wheels. Compressing hydrogen is around 90% efficient. Fuel cells in vehicles are around 60% efficient at converting hydrogen and oxygen to electricity. And motors are around 90% efficient. Assuming zero energy costs to transport the hydrogen to fueling stations, your "well to wheel" efficiency is 35-40%. In practice it's around 30%. For battery electric vehicles, efficiency is around 60%.

And then there are the safety and performance issues. You need new infrastructure to store and transport hydrogen. You need special sensors to detect hydrogen leaks, as any odorant will damage fuel cells. Due to ideal gas law, refueling cools the nozzle. With a high duty cycle, the nozzle can freeze to the vehicle even in southern California. Most climates will need heating elements on the nozzle and/or vehicle to deal with this. Different fueling stations have different pressures, meaning that a 5,000psi fueling station can only fill a 10,000psi tank to 50% capacity. Fueling stations leak hydrogen, so they can't be in convenient locations like parking garages or homes.

Given these issues, I think for applications where batteries lack the required energy density, synthetic fuels are much more likely to win than hydrogen. Their safety issues are familiar to everyone and they can take advantage of existing infrastructure.

[mschuster91]

> It certainly does not! (At least, not in any meaningful sense).

The problem is, there are applications that for the foreseeable future cannot be made to work on batteries - airplanes larger than bushcraft and large-scale maritime shipping (the large ocean liners carry upwards of a million gallons of fuel).

Assuming we want to convert these away from fossil fuels - which we have to! - there are only two renewable alternatives: biofuels, which carry serious ethical implications given world hunger and soil depletion, and synthfuels made from hydrogen and sequestered CO2 as base chemicals. The problem is, synthfuels are absurdly expensive because there is no hydrogen market yet so there isn't much happening in scaling up from lab-scale.

[MadnessASAP]

There are some enormous issues regarding hydrogen storage that will need to be resolved before it will be usable on aircraft.

Pressure vessels are heavy, hydrogen is explosive, both of those are incompatible with aircraft.

[mschuster91]

That's why I said: "synthfuels made from hydrogen and sequestered CO2 as base chemicals."

You need to combine the hydrogen and CO2 into methane and from that into longer-chain liquid hydrocarbons, and that process is complex and energy-intensive even if you use microbes for the job.

[MadnessASAP]

Ohhhh.... That is what you said, apologies. Yes I'm all aboard the synthetic fuels train so long as it remains carbon neutral and can run at some reasonable degree of efficiency. Or we figure out how to make enormous amounts of power in a renewable and cheap manner.

[jes5199]

synthfuels will catch up eventually, the economics keep getting better and there’s really no alternative

[standeven]

I agree with most of what you’ve said, but there are some niche uses.

https://www.liebreich.com/hydrogen-ladder-version-5-0/

[Sohcahtoa82]

I wish I could upvote this twice. I grow so tired of people simping for hydrogen when batteries just win in every metric aside from the initial build cost, which when amortized over the life of the battery, will beat out hydrogen.

On top of the storage problems, and the problems of the energy needed to create the hydrogen, you then have to have a massive hydrogen distribution network that's on par with the current gas distribution network. With battery EVs, it's just a matter of building chargers that connect to the existing power grid, with many (possibly most) EV owners charging at home.

As far as I'm concerned, anybody pushing for hydrogen fueled vehicles is simply falling for marketing bullshit. Producing a hydrogen-powered car would likely become cheaper than a BEV, but they'll never be better for the environment in the long run, and will never be cheaper to operate. It's always going to be cheaper to just put electricity directly into a battery rather than use it to create hydrogen, distribute it, and then pump it.

[sofixa]

> I grow so tired of people simping for hydrogen when batteries just win in every metric aside from the initial build cost, which when amortized over the life of the battery, will beat out hydrogen

Batteries suck in energy density and weight and in some cases, that really matters. Battery electric planes are not even close to being feasible other than for very small in size and range planes. Hydrogen is at least feasible.

[Sohcahtoa82]

I challenge the assertion that hydrogen is feasible.

Is hydrogen more energy dense (in either energy per unit volume OR per unit weight) than traditional fuels?

It might be better than batteries, but I'd be surprised if it was any better than current fuels.

[GJim]

> Is hydrogen more energy dense ... than traditional fuels

Chemically, yes. But in reality, very far from it.

The bulky high pressure cylinders needed to store the gas (unlike propane etc, it doesn't liquify) easily weigh an order of magnitude more than the mass of gas they contain.

[wstrange]

Bio-Fuel seems more practical.

It reuses all the existing infrastructure and requires no engine modifications.

[sofixa]

No. It's practically impossible to scale them to the required level

https://www.youtube.com/watch?v=ADpsUhdIO4w a video by a pilot on SAF and why it just won't cut it.

[pstuart]

>> Hydrogen has its place in our energy economy

> It certainly does not! (At least, not in any meaningful sense).

I was speaking to the use of hydrogen for ammonia production. When we experience grid imbalances from when there's too much solar or wind energy for the grid to absorb it would be nice to put it to use in that regard rather than dumping it.

I understand and do not contest the problems that working with hydrogen creates, it makes a lousy option for a battery.

[belorn]

Green hydrogen as a power source was and still is the primary plan in the Germany green party program in order to solve the grid-scale battery issue, and was the primary argument in EU when they defined natural gas as a green transition solution. Are you saying that this strategy was the natural gas industry all along, and that green hydrogen in grid-scale size is unlikely to solve the problem of climate change?

[huijzer]

The fact is that we are now years and years into hydrogen and we still have (almost) nothing to show for it. The number of electric cars and trucks vastly outnumbers the number of hydrogen cars and trucks. So the hydrogen people moved on to factories. But with the history of cars and trucks in mind, it will probably lead to nothing too. Also note that all hydrogen cars and trucks are funded by subsidies and still they one by one go out of favor. It just appears that it doesn't work. It's probably time to call it a day by now.

[hot_gril]

There are a lot of hydrogen vehicles on the road already, especially buses.

[standeven]

Where?

[hot_gril]

Uh nvm, a lot of the ones I was thinking of are natural gas. The hydrogen ones are mostly in China.

I've also seen many Toyota Mirais on the road in California, but turns out their sales are poor nowadays.