One thing they also mention is how incredibly cheap storage of natural gas is. https://en.wikipedia.org/wiki/Power-to-gas#Efficiency The efficiency of power to gas is not great, but it's about the same as this thermal storage method, with probably much longer lifetimes,easier transportation and more general utility (the natural gas could for example be converted to methanol using the holy grail catalyst that was in the news recently).

The power to gas is also carbon neutral, even negative depending on what you decide to do with the natural gas (if you don't burn it for power but use it for industrial chemistry, you get some sequestration out of it).

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pfdietz 2 days ago | parent [-]

The problem is the cost of getting the carbon and hydrogen to make the natural gas. If you're making a synthetic fuel, you might as well make methanol, which can be stored as a liquid, and is about as easy to make from syngas as methane.

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capitainenemo a day ago | parent [-]

Yeah, did mention the methanol option as an additional step once the natural gas is created. But is the cost of getting the carbon and hydrogen that high? In a P2G system you'd be electrolysing water (plentiful) and combining it with carbon dioxide (also relatively plentiful, although it can also be linked to an existing fuel burning plant for better efficiency). There are existing production systems using this approach right now with surplus energy from renewables described in the wikipedia article.

	▲	pfdietz a day ago \| parent [-]
		Getting it from existing fuel burning plants defeats the whole purpose. Direct air capture is out, so it'll have to be recovered from the combustion of the synfuel. Using the Allam cycle has been explored to do this (you also have to store the oxygen from electrolysis for later use in this oxyfuel combustion cycle) but it ends up being more expensive than just burning hydrogen, if there's reasonable geology for hydrogen storage. So, if this thermal storage scheme is cheaper than hydrogen, as it appears it will be, then these alternative synfuel schemes are ruled out.