Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Solar energy solves global warming

unchartedterritories.tomaspueyo.com

Post reply on HN
Print view View original

91–100 of 119 posts

Re: Solar energy solves global warming

#91

Post by pfdietz »

stickyricky wrote: post #12
pfdietz wrote: post #7

A problem with making methane is some will leak, and in the short to medium term methane is a very powerful greenhouse gas. A step before making methane is making hydrogen. If you can get away with just using hydrogen, it will be more efficient than going through the extra steps to make methane.

Doesn't methane break down in the atmosphere relatively quickly? I think the goal of this proposal is to reduce CO2 in the atmosphere. Producing hydrogen doesn't contribute to that goal (which isn't to say its a bad idea only that the hydrogen production facilities can exist independently of this proposal).

A possible solution is to make the hydrogen by electrolysis of brine. This can make hydrogen and chlorine (and alkali) instead of hydrogen and oxygen.

If the chlorine is released into the troposphere during the day, it is quickly photolysed (in about 10 minutes at noon) into chlorine radicals, which near instantly react with methane, extracting a hydrogen atom. It should be possible for this to more than make up for small leaks of methane (or to counteract other independent sources of methane).

Re: Solar energy solves global warming

#92

Post by NickM »

pfdietz wrote: post #87
hannob wrote: post #77

Earlier quoted context omitted.

None of these chemicals will be used in people's homes in any meaningful quantity. That's just not going to happen due to the conersion inefficiencies.

Right. The more efficient way to use methane to heat a home (vs. current furnaces) is to burn it in a CC power plant and heat the home with a heat pump.

Yes, that would be more efficient, but there are so many edge cases where switching an existing home to use heat pumps is prohibitively difficult or expensive.

Maybe you have radiators that require higher temps than can be efficiently produced by heat pumps. Maybe you live in a place where the air gets too cold for air source heat pumps to be cost effective. Maybe you want to install ground source, but you live in a city and don't have a big enough yard. Maybe you have a big enough yard but local geological conditions aren't conducive to digging deep enough.

Not to mention all the people who just don't want to bother switching, or who don't have the money to switch, or prefer the reliability of the natural gas over the electrical grid, or...etc.

Or just look at the culture wars that are already starting over gas stoves, when nobody has even been required to get rid of their existing gas stove, and people are just talking about changing the rules for new construction.

There are just so many edge cases where it's hard to get people to switch off natural gas. If we can make green methane, all those problems are simultaneously solved with zero disruption to anyone's homes/lifestyles/etc.

Re: Solar energy solves global warming

#93

Post by slashdev »

narag wrote: post #75
slashdev wrote: post #51

Earlier quoted context omitted.

That’s nonsensical, because you burn the methane and put the carbon right back into the atmosphere. It didn’t clean anything. It’s merely a carbon neutral form of chemical energy. H2, ammonia, methanol would be just as carbon neutral.

Well, it's there in the title of the article, so don't shoot me. If the premise of the article is bs, it doesn't make sense to discuss efficiency. Is it nonsensical though? IDK, it seems somehow better than extracting the gas from the ground and adding it to the system. Also if there's another more complex chemical not for burning, that you can synthesize from the methane, it would be a net gain.

It’s much better than extracting it from the ground, hence carbon neutral. It is not carbon negative though.

The article was reasonably well written, but I can see how you’d draw that conclusion if you only read the title.

Re: Solar energy solves global warming

#94

Post by tastyfreeze »

hannob wrote: post #77
NickM wrote: post #53

Earlier quoted context omitted.

the first one you will look at is hydrogen, because it's the simplest Simplest chemically != simplest to use in practice. There are already millions of miles of natural gas pipelines leading directly to peoples' homes, and those pipelines cannot be used with hydrogen (not to mention all the appliances they feed). Renewable methane is a dead simple drop-in replacement for natural gas. None of the other alternatives yo…

None of these chemicals will be used in people's homes in any meaningful quantity. That's just not going to happen due to the conersion inefficiencies.

Methane can be produced passively by digesting organic material in an anaerobic environment. Using electricity to synthesize methane is not a good use of electricity when bacteria do it much more efficiently.

Re: Solar energy solves global warming

#95

Post by BobbyJo »

kibwen wrote: post #79
BobbyJo wrote: post #60

Earlier quoted context omitted.

Not really. The reason coal was so popular was because you didn't really need any specialized infrastructure. It is a solid you can just ship using the same trains and trucks you use for TVs and apples. So you're really only giving up the mines and power plants.

This seems to be arguing that the existence of natural gas pipe infrastructure is somehow a benefit of natural gas, rather than a downside. The pipes are an expense, to say nothing of the fact that even our best-maintained pipes are leaking 2% of their gas directly into the atmosphere per year (the worst are leaking double or triple that). A hunk of coal that falls off a truck doesn't contribute to emissions; a leaky…

Not at all. In another comment I make a similar statement to yours, I'm just pointing out that the coal:methane comparison doesn't make sense.

Re: Solar energy solves global warming

#96

Post by foxyv »

hannob wrote: post #48
foxyv wrote: post #35

Earlier quoted context omitted.

The problem with hydrogen is the storage. Although electrolysis and other methods of generating hydrogen are fairly efficient, the cost to compress it is obscene. Sabatier production of Methane is comparable, however we already have infrastructure to use Methane and storage is a solved problem. Methanol production requires methane as a synthesis gas so it just adds another step. Plant based methanol has all the same…

> Methanol production requires methane as a synthesis gas so it just adds another step. That's not true. Methanol can be made directly from CO2 and H2. This has been tried more than a decade ago: https://www.carbonrecycling.is/ They just opened a much larger plant with this technology in China. There's currently a huge push in the shipping industry towards renewable methanol, and there are a bunch of companies invest…

E-Methanol is okay as a carbon neutral fuel and solvent. At 50-60% efficiency it makes an excellent fuel to create from electricity. But it is still a long way from competing with battery and pumped hydro. It's fuel cell efficiency is only 30% with current technology after the 40-50% losses from the creating of the fuel itself. You can buy a lot of transmission wire at that price point.

All of these technologies illustrate how obscenely difficult it will be to put the carbon genie back in the bottle and what a miracle lithium chemistry batteries really are.

Re: Solar energy solves global warming

#97

Post by slashdev »

pfdietz wrote: post #87
hannob wrote: post #77

Earlier quoted context omitted.

None of these chemicals will be used in people's homes in any meaningful quantity. That's just not going to happen due to the conersion inefficiencies.

Right. The more efficient way to use methane to heat a home (vs. current furnaces) is to burn it in a CC power plant and heat the home with a heat pump.

I questioned if the gain from the heat pump really exceed the losses from generation and transmission.

It seems CC plants are 45-57% efficient, so let’s go with 50%. A gas furnace is from 80% to 95% depending how old it is.

The heat pump would need to be roughly 2x efficiency to break even. They can be 3x or higher (since they move heat around rather than generating it.) Your statement surprisingly checks out.

So obviously it makes zero sense to use electricity to create methane to then burn for heat. Reality is messy though, sometimes we do things inefficiently because there are other constraints. Being unable to afford to convert to a heat pump system, or being in a climate where it won’t work well.

Re: Solar energy solves global warming

#98

Post by pfdietz »

slashdev wrote: post #97
pfdietz wrote: post #87

Earlier quoted context omitted.

Right. The more efficient way to use methane to heat a home (vs. current furnaces) is to burn it in a CC power plant and heat the home with a heat pump.

I questioned if the gain from the heat pump really exceed the losses from generation and transmission. It seems CC plants are 45-57% efficient, so let’s go with 50%. A gas furnace is from 80% to 95% depending how old it is. The heat pump would need to be roughly 2x efficiency to break even. They can be 3x or higher (since they move heat around rather than generating it.) Your statement surprisingly checks out. So obv…

The only way, from an efficiency point of view, that it would make sense to burn gas in a home for heating is with a gas-fired heat pump (or home cogeneration driving an electric heat pump, and also using the waste heat). But these have not been installed much, probably because of cost.

The waste heat from the combined cycle plant could also be used for district heating.

Highest efficiency CC plants are like 62% efficient (but that's on a LHV basis, which ignores latent heat of water of combustion.)

Re: Solar energy solves global warming

#99

Post by foxyv »

Gibbon1 wrote: post #82
foxyv wrote: post #35

Earlier quoted context omitted.

The problem with hydrogen is the storage. Although electrolysis and other methods of generating hydrogen are fairly efficient, the cost to compress it is obscene. Sabatier production of Methane is comparable, however we already have infrastructure to use Methane and storage is a solved problem. Methanol production requires methane as a synthesis gas so it just adds another step. Plant based methanol has all the same…

I think at this point it's just batteries. You can just quietly[1] site them on random brownfield land and be done with it. [1] Quietly pull the permits, drop the batteries, and connect to the grid without alerting the Sierra Club or the usual obstructionists.

Pumped Hydro is a nice stopgap to help storage keep up with wind and solar. Batteries are still only a small percentage of our production numbers. We are still only just about 6GW which is about 0.2% of average totals. Current projections are showing about 860GW by 2030 which is about 25% of current average production. However production will need to increase significantly to offset current fossil fuel emissions.

We are reaching the point where solar and wind are so insanely cheap that it's raining soup. Everyone is scrambling to find a bigger bucket.

Re: Solar energy solves global warming

#100

Post by foxyv »

pfdietz wrote: post #39
foxyv wrote: post #35

Earlier quoted context omitted.

The problem with hydrogen is the storage. Although electrolysis and other methods of generating hydrogen are fairly efficient, the cost to compress it is obscene. Sabatier production of Methane is comparable, however we already have infrastructure to use Methane and storage is a solved problem. Methanol production requires methane as a synthesis gas so it just adds another step. Plant based methanol has all the same…

For static applications, hydrogen can be easily stored underground. Energy is used to compress it, but that energy can be recovered by running it through an expander (and if the compression/expansion is done in stages to approximate isothermal compression, the round trip efficiency of this can be high.)

That's really neat! I've mostly seen explanations about Hydrogen as a vehicle fuel so I've never stumbled on cavern storage. It makes sense to use isothermal compression. Especially if you can recover the energy from decompressing the hydrogen using a turbo expander which would be obscenely difficult on a vehicle.
Post reply on HN