Cheap, green hydrogen would be a breakthrough in clean energy • Hacker News Board

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

#141

Post by jml7c5 » Wed, Jun 22, 2022, 3:00 AM UTC

sumy23 wrote: post #135

mytwocentsworth wrote: post #130

The second paragraph of TFA passingly mentions liquid fuels, then fails to elaborate. A blockbuster point is thereby deprived of appropriate emphasis. According to Wikipedia[1], "Electrofuels, also known as e-fuels or synthetic fuels, are a type of drop-in replacement fuel. They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from sustainable electricity sources such…

E-fuels don’t do anything other than make the original carbon consumption more efficient. Let’s say you have a coal power plant and capture the carbon to make e-fuel. You’ve made the coal more efficient, as you get the same amount of electricity + fuel, but it’s still carbon positive due to the laws of thermodynamics. E-fuels, while cool, aren’t that promising to me.

The assumption is both that the carbon is obtained via atmospheric capture and that the energy for fuel synthesis comes from renewables.

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

#142

Post by enragedcacti » Wed, Jun 22, 2022, 3:12 AM UTC

sumy23 wrote: post #135

mytwocentsworth wrote: post #130

The second paragraph of TFA passingly mentions liquid fuels, then fails to elaborate. A blockbuster point is thereby deprived of appropriate emphasis. According to Wikipedia[1], "Electrofuels, also known as e-fuels or synthetic fuels, are a type of drop-in replacement fuel. They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from sustainable electricity sources such…

E-fuels don’t do anything other than make the original carbon consumption more efficient. Let’s say you have a coal power plant and capture the carbon to make e-fuel. You’ve made the coal more efficient, as you get the same amount of electricity + fuel, but it’s still carbon positive due to the laws of thermodynamics. E-fuels, while cool, aren’t that promising to me.

Unless of course you have a source of carbon you can't yet replace effectively or at scale, or you extract the carbon from the environment[1]. the second option (and efuel in general) definitely isn't ready for primetime but it could be a viable option in the future to keep some classes of old tech running rather than expending effort building out new tech at massive scales when it could be used more effectively elsewhere.

[1] https://en.wikipedia.org/wiki/Carbon-neutral_fuel#Sources_of...

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

#143

Post by sumy23 » Wed, Jun 22, 2022, 3:13 AM UTC

enragedcacti wrote: post #142

sumy23 wrote: post #135

Earlier quoted context omitted.

E-fuels don’t do anything other than make the original carbon consumption more efficient. Let’s say you have a coal power plant and capture the carbon to make e-fuel. You’ve made the coal more efficient, as you get the same amount of electricity + fuel, but it’s still carbon positive due to the laws of thermodynamics. E-fuels, while cool, aren’t that promising to me.

Unless of course you have a source of carbon you can't yet replace effectively or at scale, or you extract the carbon from the environment[1]. the second option (and efuel in general) definitely isn't ready for primetime but it could be a viable option in the future to keep some classes of old tech running rather than expending effort building out new tech at massive scales when it could be used more effectively else…

> Unless of course you have a source of carbon you can't yet replace effectively or at scale.

Wouldn't it be better to capture the carbon and sequester it? How is capturing the carbon and then burning it again (via e-fuel) good?

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

#144

Post by trinovantes » Wed, Jun 22, 2022, 3:29 AM UTC

elihu wrote: post #93

rich_sasha wrote: post #59

Earlier quoted context omitted.

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 tim…

The US already struggles to build transmission lines across state lines. Building across nations is basically impossible.

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

#145

Post by mytwocentsworth » Wed, Jun 22, 2022, 3:34 AM UTC

sumy23 wrote: post #143

enragedcacti wrote: post #142

Earlier quoted context omitted.

Unless of course you have a source of carbon you can't yet replace effectively or at scale, or you extract the carbon from the environment[1]. the second option (and efuel in general) definitely isn't ready for primetime but it could be a viable option in the future to keep some classes of old tech running rather than expending effort building out new tech at massive scales when it could be used more effectively else…

> Unless of course you have a source of carbon you can't yet replace effectively or at scale. Wouldn't it be better to capture the carbon and sequester it? How is capturing the carbon and then burning it again (via e-fuel) good?

It's not that capturing carbon and then releasing it again is good. What's good is that the liquid fuel (made from green energy plus captured carbon) can be used in existing cars, ships and aircraft.

There's more info in the Wikipedia article I linked above. "In 2021, Audi announced that it was working on e-diesel and e-gasoline projects.

"By 2021, the European Federation for Transport and Environment advised the aviation sector was needing e-kerosene to be deployed as it could substantially reduce the climate impact of aviation."

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

#146

Post by shawndrost » Wed, Jun 22, 2022, 3:38 AM UTC

ncmncm wrote: post #99

scythe wrote: post #96

Earlier quoted context omitted.

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 punishme…

I think this is incorrect; I have seen GWP20 numbers like 38, eg here[1], or lower numbers for GWP100. Do you have a citation?

[1] https://www.greenbiz.com/article/inside-misconception-hydrog...

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

#147

Post by ggm » Wed, Jun 22, 2022, 3:46 AM UTC

The FF industry is leaping (has leapt, historically) on CCS as a getout clause and has sunk french metric tonnes of money into CCS. So far, its uneconomic except for the specific use of pumping gas into wells to make them more productive, which leads to more fugitive gas. No significant CCS experiment worldwide has achieved its goals as sequestration. The one in Western Australia releases so much CO2 it has to pay a penalty cost, to maintain status. (its a gas field associated with other extractive industry I believe)

This money they've sunk: its not their money: they've been doing it off the public teat as "research" or, when it is their money, its booked to R&D and has massive royalty & tax offset benefits. Its a shellgame.

The inclusion of blue hydrogen+CCS in this piece is really regrettable: its being used to avoid having to wear the cost of going to green hydrogen, which is abandoning FF inputs. For holders of shares in coal and gas, this is not optimal so they oppose green and argue abatement by CCS is "the one"

It doesn't work. CCS is a giant con. The evidence is strong that at scale CCS is not working, and will waste years of time, billions of dollars of cost, and gigatonnes of CO2, to prove it.

Overall I like Gates trying to help. He's been badly advised when it comes to CCS.

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

#148

Post by ad404b8a372f2b9 » Wed, Jun 22, 2022, 3:50 AM UTC

ggm wrote: post #147

The FF industry is leaping (has leapt, historically) on CCS as a getout clause and has sunk french metric tonnes of money into CCS. So far, its uneconomic except for the specific use of pumping gas into wells to make them more productive, which leads to more fugitive gas. No significant CCS experiment worldwide has achieved its goals as sequestration. The one in Western Australia releases so much CO2 it has to pay a…

FF: fossil fuel. CCS: carbon capture and storage.

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

#149

Post by sumy23 » Wed, Jun 22, 2022, 3:51 AM UTC

mytwocentsworth wrote: post #145

sumy23 wrote: post #143

Earlier quoted context omitted.

> Unless of course you have a source of carbon you can't yet replace effectively or at scale. Wouldn't it be better to capture the carbon and sequester it? How is capturing the carbon and then burning it again (via e-fuel) good?

It's not that capturing carbon and then releasing it again is good. What's good is that the liquid fuel (made from green energy plus captured carbon) can be used in existing cars, ships and aircraft. There's more info in the Wikipedia article I linked above. "In 2021, Audi announced that it was working on e-diesel and e-gasoline projects. "By 2021, the European Federation for Transport and Environment advised the avi…

Sorry, but I'm still not seeing how e-fuels are beneficial without violating the laws of thermodynamics. A plane is going to produce the same amount of CO2 whether kerosene or e-kerosene is used. The only way e-kerosene makes sense is if its production uses less CO2 than traditional oil extraction and refining. Given the relative simplicity of oil extraction, I find it hard to believe this will be the case. Maybe it makes sense in Europe where geopolitical considerations like energy independence outweigh strictly reducing CO2 emissions.

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

#150

Post by sumy23 » Wed, Jun 22, 2022, 3:56 AM UTC

jml7c5 wrote: post #141

sumy23 wrote: post #135

Earlier quoted context omitted.

E-fuels don’t do anything other than make the original carbon consumption more efficient. Let’s say you have a coal power plant and capture the carbon to make e-fuel. You’ve made the coal more efficient, as you get the same amount of electricity + fuel, but it’s still carbon positive due to the laws of thermodynamics. E-fuels, while cool, aren’t that promising to me.

The assumption is both that the carbon is obtained via atmospheric capture and that the energy for fuel synthesis comes from renewables.

Ok well that's a bad assumption. Atmospheric capture is basically impossible (at scale) due to the size of the atmosphere and the density of carbon within it. Atmospheric capture is not something I'd bet the farm on.