With the recent advances of turning CO2 into other substances, such as propane, should we be focusing more on closing the carbon cycle and simply be producing fossil fuels from the waste products of yesteryear?
Naively, it feels like we understand C, O and H, better than we understand some of the rare metals we're now introducing in the name of climate change.
I get the worries, Lithium mining causes ecological damage, but every sort of resource extraction causes ecological damage. Every kilogram of pollution generated from lithium mining prevents many times more pollution generated from oil extraction and emissions. Lithium, cobalt, and the rest aren't exotic materials, the battery industry is huge and has many decades of experience building batteries.
Synthesizing hydrocarbons is an important technology. But that process is incredibly energy intensive, and it's much more efficient to use electricity to just charge a battery. The scale of production of synthetic hydrocarbons isn't anywhere close to where it would need to be to make a dent in climate change. I think that electrofuels will be very important in aviation - they're the only apparent pathway to run jet engines without emissions. But it will be a long time, if ever, before that technology is mature enough to fuel passenger vehicles at a meaningful scale.
[1] https://www.iea.org/data-and-statistics/charts/comparative-l...
[2] https://afdc.energy.gov/vehicles/electric_emissions.html
[3] https://www.sciencedirect.com/science/article/pii/S136403212...
The batteries in electric vehicles are a storage technology, so all you have to do is charge your car while the sun shines. If you need the batteries anyway it makes much more sense to put them there so you can also stop burning gasoline.
But solar still has the same storage problem in the power grid. You need something to keep the lights on at night. Lithium batteries are cost effective when it means you can avoid the cost of the whole ICE powertrain and replace buying gas with cheap daytime solar -- which also means that the production capacity for lithium batteries is going to go there.
But then you start talking about electrifying heat, for which the peak demand is when it's colder. At night. And for that it makes sense to build some more nuclear reactors.
Second, you need to specify what kind of storage you are talking. We will need a lot less short-term storage for overnight than we need for cloudy, calm days. Batteries make sense for short-term storage but are too expensive for long-term. Generated fuels, like hydrogen, may work well for long-term storage and we'll them for other things.
Third, we can overbuild solar and wind. It might be cheaper to make 3x or 5x than needed. Finally, we are going to need extra energy for carbon capture and generating fuels.
The trouble is they're both intermittent, even independent of time of day. For solar that's much less trouble because the demand is higher during the day, and aligns extremely well with air conditioning load in the summer.
But if you're relying on wind at night and then there isn't any, and you also have no solar because it's night, what's left?
> Generated fuels, like hydrogen, may work well for long-term storage and we'll them for other things.
At which point you have to add the cost of production, storage and generation facilities for some other generating technology.
> Third, we can overbuild solar and wind. It might be cheaper to make 3x or 5x than needed.
But how does that fix it? Sometimes it's calm for weeks, so your wind turbines are generating at 5% capacity for that long. Are you going to overbuild by 20x? Or build enough storage to power the entire grid for that long, even if you only use it for two weeks every three or four years?
> Finally, we are going to need extra energy for carbon capture and generating fuels.
This is a generic argument for building more of any kind of non-carbon generating capacity.
Overbuilding means that can use solar and wind more of the time. Partly because wind and solar are anti-correlated, partly because you build them in different spots, and partly because there is some energy being generated. 3x means that only need a couple weeks per year need backup. 5x means that couple days per year need storage.
The generated fuel production would already exist because need them as fuel. Repurposing natural gas storage should work for hydrogen and there is lots of that available. The power plants would need to sit around but should be able to convert natural gas to hydrogen.
> 5x means that couple days per year need storage.
But that's the problem. If you need the long-term storage at all because you have a period with ~0 output from renewables, you then need to maintain enough generating capacity to run the whole grid from something else during that period, even if you only use it once a decade. Which is enormously expensive.
> But night time usage is small, and things like charging cars can be delayed.
The night time usage is about half the peak daytime usage during the summer, and a significantly higher proportion in the winter. And it will get even higher if we switch to electric heating from fossil fuels.
You already want to be charging cars during the day anyway because solar is cheaper, but none of that is included in the existing numbers because the current number of electric cars isn't a major proportion of power consumption. We could perfectly well charge electric cars entirely from solar, but you still need to handle the existing nighttime load with something.