> make synthetic fossil fuels from atmospheric CO2.
that would actually be my preferred solution (if only it was less energy inefficient, sigh).
The problem here is that the production of hydrocarbons, ammonia, etc. from electricity can only make back its high upfront investment when it runs basically 24/7. This is a challenge for renewables.
In China which recently opened a large off-grid green ammonia plant in Chifeng, they use multiple tiers of energy storage to ensure constant electric power availability.
If the marginal value of electricity is negative, what matters if it is energy inefficient?