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Cheap, green hydrogen would be a breakthrough in clean energy

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Re: Cheap, green hydrogen would be a breakthrough in clean energy

#91

Post by ncmncm »

kkfx wrote: post #57
chicob wrote: post #41

Earlier quoted context omitted.

Of course there is green hydrogen. First of all, the green aspect of it is that the source is renewable. That's what makes it green. It's not correct to call it a net loss, because no one wants to produce power from hydrogen in order to harvest more hydrogen. There would always be a renewable input somewhere. About losses. There are always losses on each energy transformation step. The same thing applies to electrici…

It's not a matter of efficiency but of scale: we can't produce enough hydrogen by hydrolysis even with all the electricity we can produce. On contrary probably we can made electric tools to substitute tractors. Something that demand a bit of investment but last FAR longer and can run only on p.v. the hard part there would probably be convincing farmers that they do not need tractors anywhere but only for very specifi…

You insist on this, but it is not, in fact, true. All that is true is that we have not yet built out enough electrolysis equipment to produce much hydrogen. But that is an empty fact; of course, before you build something, you don't have it yet.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#92

Post by ncmncm »

bryanlarsen wrote: post #54
giantrobot wrote: post #40

Earlier quoted context omitted.

The colors of hydrogen have specific meanings. Green hydrogen - hydrogen derived from water electrolysis, ostensibly from renewable electrical sources so no greenhouse gases are produced Blue hydrogen - hydrogen derived from hydrocarbons, produces greenhouse gases as waste Pink hydrogen - hydrogen from water electrolysis from nuclear electrical sources, no greenhouse gases produced The description of "green" hydrogen…

Grey hydrogen is hydrogen derived from hydrocarbons which throws the carbons into the atmosphere. Blue hydrogen is grey hydrogen but the carbons are captured and stored. So nominally it's carbon-neutral but in practice the capture is never perfect.

Blue hydrogen is also unicorns. Probably even mentioning it can only distract.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#93

Post by elihu »

rich_sasha wrote: post #59
derriz wrote: post #25

I don't see hydrogen playing any role for energy storage or grid demand balancing. Even if all the technical and engineering challenges associated with storing and transporting it safely could be addressed, I just don't see how the economics of green hydrogen is supposed to work. The round-trip energy efficiency of electrolysis-fuel cell is poor - currently about 40%. The counter-argument is that such inefficiency do…

The point is that some countries have long dark winters, often with windless spells. Some are also lowland countries with little or no access to hydro. For green energy, you'd need to literally store months' worth of energy somehow, and the cost of doing that via batteries is prohibitive too. I guess the hope is that storing hydrogen, difficult and expensive that it is, could be made to be more like storing hydrocarb…

Having some cheap long-term energy storage option is one way to solve that problem, but another is better power grid interconnection. For instance, Chicago could get solar power from Chile in the winter time to buffer out the seasonal variability. Or if they didn't even want to have to maintain a smaller buffer to deal with day/night cycles, they could get solar power from, say, Algeria and Australia depending on time of day.

Power losses would be significant, but probably not all that worse than doing local electricity-to-hydrogen-to-electricity.

To quote wikipedia on HVDC lines:

> Depending on voltage level and construction details, HVDC transmission losses are quoted at 3.5% per 1,000 km

https://en.wikipedia.org/wiki/High-voltage_direct_current

An infrastructure project like that would probably be hugely expensive, but so is manufacturing lots of batteries or doing large scale hydrogen production and storage.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#94

Post by ncmncm »

wh33zle wrote: post #15
phkahler wrote: post #13

Earlier quoted context omitted.

Quoted post unavailable.

Can you expand why separation from water is a net energy loss?

It is absolutely trivial that separating hydrogen from water uses energy. Then, when you burn it, you get water and energy back. That is the whole point.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#95

Post by ncmncm »

pixl97 wrote: post #89
ncmncm wrote: post #73

Earlier quoted context omitted.

We already synthesize and handle industrially millions of tons of it annually, and have done for going on a century. If there were a worrying problem with ammonia, you would already be hearing about it.

Heh, this is how I know you didn't grow up on a farm. You ever see a leaking anhydrous tank and you run for your life.

My father reports feeding raw ammonia directly into furrows being cut.

Yes, a leaky ammonia tank would be a problem, but it is not exactly odorless.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#96

Post by scythe »

Barraketh wrote: post #52

Ammonia has been mentioned a few times in this thread, but I will expand a bit, because I believe it is the most promising hydrogen-based approach. Essentially, the idea is to use ammonia directly as fuel. There is an ARPA-E funded project (that I'm currently failing to find) that cracks ammonia into hydrogen and nitrogen using heat. They claim that they can create a mixture of H2 and ammonia that will burn at any re…

The problem with any fuel containing H2 in any existing engine is hydrogen embrittlement. Hydrogen is a reactive gas that attacks steel.

Ammonia fuel cells have a comparable weight proposition to hydrogen at small sizes because the tank is so much lighter. I think that has legs (or wheels?). For stationary storage, the ammonia-CO2 adduct is a solid, which is nice.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#97

Post by ncmncm »

perihelions wrote: post #75
ncmncm wrote: post #73

Earlier quoted context omitted.

We already synthesize and handle industrially millions of tons of it annually, and have done for going on a century. If there were a worrying problem with ammonia, you would already be hearing about it.

- "If there were a worrying problem with ammonia, you would already be hearing about it." We hear about it pretty regularly, https://www.google.com/search?q=ammonia+spill+site%3Areddit.... Fortunately the main use of anhydrous ammonia (agriculture) is in sparsely populated places, so its impact is limited. I think it's a questionable idea to put it in urban vehicles though.

Ammonia will not be used in urban vehicles.

It will be used in farm equipment, and in place of bunker oil in ships, and burned in combined-cycle turbines in times when wind and sun are not providing, and other, cheaper storage has been used up.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#98

Post by ParksNet »

derriz wrote: post #25

I don't see hydrogen playing any role for energy storage or grid demand balancing. Even if all the technical and engineering challenges associated with storing and transporting it safely could be addressed, I just don't see how the economics of green hydrogen is supposed to work. The round-trip energy efficiency of electrolysis-fuel cell is poor - currently about 40%. The counter-argument is that such inefficiency do…

If we want to be serious about grid storage, look to the gigantic fleet of EVs we're building out. All of those vehicles should be able to charge and discharge to the grid based on daily demand and user preference.

I'm looking at buying a base Model 3. Huge (57.5 kWh)chunk of battery that will be sitting there most of the week (wife and I both work from home).

Charging at 40c/kWh during the day (from abundant solar) and discharging at 85c/kWh (for evening peak) would yield about $23 daily - or $8,400 annually if the car was never driven.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#99

Post by ncmncm »

scythe wrote: post #96
Barraketh wrote: post #52

Ammonia has been mentioned a few times in this thread, but I will expand a bit, because I believe it is the most promising hydrogen-based approach. Essentially, the idea is to use ammonia directly as fuel. There is an ARPA-E funded project (that I'm currently failing to find) that cracks ammonia into hydrogen and nitrogen using heat. They claim that they can create a mixture of H2 and ammonia that will burn at any re…

The problem with any fuel containing H2 in any existing engine is hydrogen embrittlement. Hydrogen is a reactive gas that attacks steel. Ammonia fuel cells have a comparable weight proposition to hydrogen at small sizes because the tank is so much lighter. I think that has legs (or wheels?). For stationary storage, the ammonia-CO2 adduct is a solid, which is nice.

Hydrogen embrittlement is always hyped to the sky.

It is not a serious problem unless you are trying to keep warm, gaseous hydrogen under high pressure. So, don't. Furthermore, aluminum is quite resistant to embrittlement.

Of possibly greater moment is that it leaks, and has ~200x GHG over CO2 (including secondary effects). Leaks are not dangerous in the open, or in confined places with positive airflow, but punishment for neglect is visited on all bystanders. LN2 storage is better, where you can afford the insulation and refrigeration.

Re: Cheap, green hydrogen would be a breakthrough in clean energy

#100

Post by Jistern »

ncmncm wrote: post #97
perihelions wrote: post #75

Earlier quoted context omitted.

- "If there were a worrying problem with ammonia, you would already be hearing about it." We hear about it pretty regularly, https://www.google.com/search?q=ammonia+spill+site%3Areddit.... Fortunately the main use of anhydrous ammonia (agriculture) is in sparsely populated places, so its impact is limited. I think it's a questionable idea to put it in urban vehicles though.

Ammonia will not be used in urban vehicles. It will be used in farm equipment, and in place of bunker oil in ships, and burned in combined-cycle turbines in times when wind and sun are not providing, and other, cheaper storage has been used up.

Ammonia seems too dangerous. With cheap electricity from solar and wind, cheap hydrogen seems like a better answer. Sure, it's not a perfect answer, but it seems better because it seems much safer.

As recently as approximately 200 years ago steel was very expensive, as was aluminum. Now both of those materials are cheap and used in a plethora of applications.

Cheap electricity will similarly enable us to cost-effectively do many things that heretofore were prohibitively expensive.

The whole, "Hydrogen is bulky and difficult to store" canard of an argument doesn't sway me... at all. Hydrogen storage could certainly be improved, but even if it never were, for long distance shipping and air travel it's good enough as it is.

"But, but, but... you'd need to build ships and planes 50% larger!!!" Sure. Ok. Yes. The world is not running out of steel.

And, of course, if ships and planes were running on hydrogen instead of gasoline and diesel, a huge amount of research would go into improving hydrogen storage.

The Ford Nucleon (a nuclear-powered concept car) never made it into production, yet we do have nuclear submarines. Choosing the correct fuel for a given application is important.

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