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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

#51

Post by oh_sigh »

cagenut wrote: post #12
oh_sigh wrote: post #9

Why are we all wrapped up with hydrogen when we already have a perfectly adequate hydrocarbon infrastructure? Sure, digging up old buried hydrocarbons and burning them isn't good, but couldn't we start synthesizing light hydrocarbons using green technology, so at least those usages are carbon neutral?

All of the synthetic light hydrocarbons (e-fuels) involve extra energy on top of the hydrogen production. Its pretty much right there in the name (hydro carbon). So for instance, we could make a ton of hydrogen and then burn it for energy, or we could make a ton of hydrogen, add in a few hundred kilos of carbon and more energy to produce e-fuels that we then burn for energy. For logistics reasons it will almost certa…

Right, but the problem is really with hydrogen handling, and all the complexities that would be pushed onto, say, every vehicle. Keeping a hydrocarbon in a container is much, much easier than keeping a single hydrogen atom in a container.

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

#52

Post by Barraketh »

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 required flame temperature (H2 burns too fast / hot for existing turbines, ammonia too slow, so a mixture is the right way to go). Theoretically, with this process, you could use ammonia as a drop-in replacement for LNG. The LNG infrastructure can also be converted to carry ammonia instead.

Now, there are still obvious energy losses from creating and then burning ammonia. One thing that this technology could be very helpful with is overcoming the NIMBY-ism around nuclear power - that is, build nuclear reactors to produce ammonia, then ship the ammonia to where it will be used. It would obviously be more efficient to just run power lines from nuclear power plants, but given the wide-spread opposition, it could be politically easier to build the nuclear plants in the middle of nowhere.

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

#53

Post by kkfx »

ravenstine wrote: post #20
phkahler wrote: post #13

Earlier quoted context omitted.

Quoted post unavailable.

> separate it from water, which is a net energy LOSS This is true of every form of energy transfer. There is never, ever 100% energy maintained, and maybe you'll be stunned at how inefficient existing energy sources are.

It's not a matter of efficiency but a matter of scalability: hydrogen generated by hydrolysis demand so much energy that we can't produce it on the needed scale, no matter how much it can cost.

Methane extraction is absurdly costly, transport and storage are no less absurd BUT we can do it on a needed scale. That's the sole thing that matter. Similar if for hydro: mountain hydro is fantastic, we MUST develop it as much as possible, but it demand mountains and water. For some part of the world it's ok, they are there both in needed quantity essentially all the year, for some other they are not. You can power Norway on hydro with little nuclear backup, you can't power Mongolia even if Mongolia have very little needs compared.

Similarly we can imaging electric commercial trains that only run on p.v. surplus, for all non-perishable goods that might be ok if well designed on scale. We probably can design that on scale in many, many areas of the world. We can't to the same for ships, for plane, for cars. We can't do that for perishable goods of passengers transits.

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

#54

Post by bryanlarsen »

giantrobot wrote: post #40
phkahler wrote: post #13

Earlier quoted context omitted.

Quoted post unavailable.

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.

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

#55

Post by [deleted] »

causi wrote: post #32
hnlmorg wrote: post #24

Earlier quoted context omitted.

> For hydrogen to be green is has to either A) be more green than storing the generating power in batteries I thought batteries had some pretty toxic elements inside them? I don’t know much about using hydrogen as a power source so I’m interested to understand how it’s less green than batteries.

Correct. For hydrogen to be green it has to be more green that producing and using batteries. We're already past that point. Well past it, in fact. The generation-to-tires efficiency of BeVs is 77%. For hydrogen it's 33%. Modern fuel cells have an H2 to electricity efficiency of 55%. You could make that 100% and it would still be less green than using batteries.

[deleted]

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

#56

Post by [deleted] »

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…

[deleted]

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

#57

Post by kkfx »

chicob wrote: post #41
phkahler wrote: post #13

Earlier quoted context omitted.

Quoted post unavailable.

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 specific activities...

If you use all Island electricity you can't even produce enough hydrogen to power a hypothetical nations-wide fleet of cars...

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

#58

Post by moralestapia »

ravenstine wrote: post #20
phkahler wrote: post #13

Earlier quoted context omitted.

Quoted post unavailable.

> separate it from water, which is a net energy LOSS This is true of every form of energy transfer. There is never, ever 100% energy maintained, and maybe you'll be stunned at how inefficient existing energy sources are.

I may be wrong about this but I recall reading it on a book about the history of energy.

Anyway, supposedly around 99% (!) of the net energy of fuels gets lost from the source to your home. This due to energy conversion, loss in transmission lines, transformers, you own electrical installation, battery charging/discharging and other inefficiencies on the grid or the devices you use.

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

#59

Post by rich_sasha »

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 hydrocarbons, basically in a hole in the ground. Then you could produce it in the windy sunny months and use it in winter.

Maybe...

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

#60

Post by moralestapia »

chicob wrote: post #48
L_226 wrote: post #39

Sad that there is no mention of ammonia, everyone knows this is the most efficient method of storing and transporting hydrogen.

I didn't know that. It certainly is safer. Ammonia production, as I already mentioned in another reply, currently requires natural gas as as source of hydrogen. Regardless of its use as a way of storing energy, it is already a very important industrial ingredient. Namely for fertilizer production. As I see it, the only major problem with the current technology is that it might not be adaptable to new sources. New pla…

My bet is on ammonia but yeah the economics will get tricky as producers are going to ask themselves "will I get more money if I sell this as fertilizer or as fuel?"

Kind of what happens with corn-based bioethanol, where they have to compete with the regular food market and viceversa.

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