When considering synthetic chemicals made from solar energy, methane is probably one of the last you should consider.
Making any type of chemical energy carrier comes with substantial losses, so whenever you can, using electricity directly is better.
If you absolutely need a chemical energy carrier, the first one you will look at is hydrogen, because it's the simplest and you avoid all the direct air capture or other CO2 sourcing issue.
If H2 does not work due to its low volumetric energy density, the next one to consider is ammonia. It has a higher energy density, but it also has some downsides. It's very toxic, it does not burn very well, and burning it causes nasty side products like NOx and N2O.
Then there's methanol. In case you want a hydrocarbon, that's almost always better than methane. It's a liquid, which is a huge advantage in ease of handling. Transporting and storing it is a lot easier compared to any type of gas.
Methane has the big disadvantage that it's itself a potent greenhouse gas. (Btw, hydrogen also is an indirect greenhouse gas, although not as strong as methane.) The only thing methane has in its favor is existing infrastructure, but it's a weak argument compared to the other downsides.
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 you mentioned share that property, and I think you're seriously under-weighting the importance of it.
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.
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.)
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.
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.
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 problems as ethanol. Until we are running electrified tractors and equipment we will probably be carbon positive when producing methanol. There are a few processes which are using waste from coal and concrete plants, but they are unlikely to scale enough to make Methane unnecessary.
Currently the best way to store surplus electricity are batteries and pumped hydro.
> 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 investing in this space.
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.
But I guess you can make a lot of methanol in summer and burn it in winter, storing it cheaply for months. Batteries so far seem maybe ok at balancing diurnal power generation / use patterns but not seasonal storage.
Yeah, it is definitely not a bad idea for heating fuel, feed chemical, racing fuel, jet fuel, etc... Just replacing the natural gas produced methanol would be nice. However, wind energy has high availability in the winter and batteries would make up for blizzards and shortfalls. Canada is having a lot of good results from wind energy. In addition, they make a ton of energy from hydroelectricity.
Every country is different, E-methanol may be a solution for a few places. However it is not something I would personally invest in.
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.
A turboexpander in a car would add an obscene amount of cost to an already expensive fuel cell vehicle. Also, it would be a fire and explosion hazard requiring a ton of maintenance.
That sounds completely unsubstantiated. Nothing involved here is that complicated or expensive. In fact, the whole thing should cost less than a comparable BEV given how little raw material you need. And if properly designed, it should be perfectly safe.
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.
> There's got to be tens of trillions of dollars in deployed methane infrastructure
Highly doubt it is worth that much presently, so even if the investment was that large (which I doubt) we certainly aren't looking at walking away from that much presently.
The big reason to move away from methane is that gas delivery infrastructure is expensive to maintain, and nearly impossible to keep leak free. Reusing existing infrastructure implies investing in its maintenance, which may be more expensive than building new infrastructure for liquid fuel (which itself already exists).
Sure, but if we could reuse the coal infrastructure as part of a transition away from fossil fuels, why wouldn't we consider that?
Unlike methane, coal is mostly just used for power generation, and there's relatively little infrastructure associated with transporting it. Natural gas is used for furnaces, stoves, dryers, hot water heaters, etc. and there are millions of miles of pipes and associated infrastructure used to transport it directly to peoples' homes.
The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense, not to mention all the backlash you get from people who love their gas stoves and grills. If we could just switch to generating renewable methane it would be a huge win in terms of logistical simplicity and would minimize disruption to peoples' day to day lives, which would probably make folks a lot more willing to accept it without putting up a huge fight.
> The complexity and cost for retrofitting hundreds of millions of homes and electrifying all the associated appliances is immense
This is overselling the difficulty. What you're saying is true, but you don't need to rip out functioning appliances. Appliances have a finite service lifetime; once they fail, replace them with electrified appliances. Already here in the year 2023, I wouldn't dream of building a house with a gas stove or gas heating. Induction stoves are just plain better than gas stoves, and heat pumps are cheaper than gas heating once you factor in that the gas-heated house will need a separate AC installation for cooling, whereas the heat-pump house won't. These days, methane doesn't make sense anywhere except at the power generation end, and power generation sources are fungible and can be gradually replaced on their own schedule.
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 methane pipe does, which can actually make natgas plants overall worse for emissions than coal.
Exactly - it is an argument for continuing to use coal, because we have valuable infrastructure even though we know how bad it is for the environment. Which explains why it is so hard to stop using coal.
In the US, the share of power being generated by coal has fallen from 50% in 2005 to 20% in 2022. (In absolute terms, which is what really matters in an emissions context, it's fallen from 2T kwh to 0.75.) To phase out existing infrastructure just takes incentives and time (and 18 years isn't even that much time on the scale of infrastructure investments). The same can happen to methane infrastructure, especially since non-fossil alternatives are far more viable than they were when coal began to be phased out.
And the US has stopped building new coal fired power plants, so a decay to zero is just a matter of time (although it could and should be accelerated.)
The thing is: Most of that infrastructure is obsolete in any case.
These synthetic chemicals will play a role in industry and shipping, probably also in long-duration storage. But they won't be in widespread use like fossil gas today. They're just too inefficient.
Once thing that's missing (from both the article here, and for example the whole hydrogen discussion in Germany) is the round-trip efficiency.
Now the author of the article would likely argue that with prices dropping as fast as they do, a 60% efficiency is just a few years delay away from being economically efficient. (A quick search came up with a 68% efficiency for fuel cells and "80% - 95%" for electrolysis, putting the whole thing at 54%-65%)
But I can't help but think we'll come up with something a bit more efficient, because that'll be more viable sooner, and more profitable in the long run.
The relevant applications for hydrogen are ones where efficiency doesn't much matter (long term storage, rare event grid backup). What matters is minimizing capital cost, which probably means using combustion turbines, not fuel cells.
I've been following Terraform Industries for a while, and it does strike me as obvious that H2 will be the preferred form of energy storage medium in the long run, not just an intermediate species.
Depending on the conditions, if you're doing day-night energy storage, then you would like to fill up the H2 tank and then burn it when demand ramps up.
The only role I see for methane is when your H2 tank is already filled up but your solar panels are still producing. This is not just possible, but deterministically required whenever solar gets deployed enough for seasonal storage to be necessary.
Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago, as >30% and you get stuff like zeroed-out energy prices during the day. We have not solved the day-night (daily) energy storage problem, which only requires storing energy for a matter of hours.
When you go to something like 60% renewables, then even crazier stuff happens. Overproduction during sunny times goes bananas and (assuming daily storage is solved, which it isn't) seasonal issues start to arise. I don't think H2 will ever work for seasonal storage, although I think it's fine for multi-day storage scenarios. It's not theoretically impossible, I just compare to the equivalent that we have for natural gas and realize you would need MANY TIMES that level of investment to save the same amount of energy in H2. Plus, fossil fuel gas producers are mostly at a constant level, whereas solar production outright needs summer-to-winter storage.
What I don't buy is that these units will be disconnected from the grid and be economical by their gas products. No way, no how. What you want is to run the chemicals plant with low-voltage solar power locally, and trade-off with the grid as is economical.
>Right now California is something like 35% solar + wind energy, and the "duck curve" is nearly maxing out. This was predicted in extreme specificity 20 years ago
Legislated. Its easy to predict something if you write it into law resulting in shutdown of Nuclear power station (Diablo Canyon)
>The main driver deterring PG&E from seeking a 20-year operating licence extension is the 2015 renewable portfolio standard (RPS) of producing 50% of its electricity from qualified renewable energy sources by 2030. PG&E’s model for the future cost of operating Diablo Canyon indicated that the cost per kilowatt hour was going to almost double, since the company would be forced to lower the amount of power it could produce from the plant in order to meet the state’s requirement. Dropping the capacity factor from the current 92% to say 50% would virtually double the price per kilowatt hour since costs are largely fixed.
>The state law which effectively dictates that by 2030 Diablo Canyon should operate at lower capacity each year and buy in power from intermittent renewables has apparently sealed the fate of the plant.
California has 5 GW of grid batteries (I think that's 20 GWh of storage).
The peak demand today at CASIO is around 36 GW (interestingly, ERCOT's peak is much higher. Texas should invest in efficiency.)
The "duck curve" looks like it's already partially ameliorated by batteries, and not that much battery capacity will be needed to smooth it out entirely.
Making any type of chemical energy carrier comes with substantial losses
The goal presented in the article seems to be cleaning the atmosphere, not generating chemicals. So H2 and ammonia would be irrelevant. And it's not so much about maximazing efficiency as not losing too much.
The alternative should be other carbon-based chemicals, as useful as methane, needed in huge volumes and with a practical process of extraction using solar panels. Is there something like that?
Also, is there another product with the same characteristics with methane as a starting point?
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.
Making any type of chemical energy carrier comes with substantial losses, so whenever you can, using electricity directly is better.
If you absolutely need a chemical energy carrier, the first one you will look at is hydrogen, because it's the simplest and you avoid all the direct air capture or other CO2 sourcing issue.
If H2 does not work due to its low volumetric energy density, the next one to consider is ammonia. It has a higher energy density, but it also has some downsides. It's very toxic, it does not burn very well, and burning it causes nasty side products like NOx and N2O.
Then there's methanol. In case you want a hydrocarbon, that's almost always better than methane. It's a liquid, which is a huge advantage in ease of handling. Transporting and storing it is a lot easier compared to any type of gas.
Methane has the big disadvantage that it's itself a potent greenhouse gas. (Btw, hydrogen also is an indirect greenhouse gas, although not as strong as methane.) The only thing methane has in its favor is existing infrastructure, but it's a weak argument compared to the other downsides.