"This heat powers a thermochemical reactor that turns CO2, water and methane into syngas"
The methane has to come from biomass, so this isn't quite closing the loop here on a full solar only process. Pure CO2 and water to synfuels is still wildly energy inefficient.
When you say inefficient, do you mean that the process results in more entropy than work-producing fuel than another method of recomposing molecules into methane, such as biological processes?
If the Hysatas electrolyzer[1] is for real and scales up, making hydrogen is going to get way more efficient. They can make then make synfuels out of hydrogen for about a 40% loss. Eventually, they could put these electrolyzers at major airports and refuel hydrogen planes without having to move the hydrogen much. That's the big weakness of hydrogen is that it can't be moved around easily in pipelines. It can be stored in underground caverns under low pressure for cheap though.
>>> Pure CO2 and water to synfuels is still wildly energy inefficient.
> If the Hysatas electrolyzer is for real and scales up, making hydrogen is going to get way more efficient.
From the article, Synhelion has a thermal reactor now: solar radiation directed by heliostats into a thermal reactor that feeds a Fischer-Tropsch process. It seems difficult to establish relative efficiency of the whole to the Hysatas electrolyzer which is one component of a larger chain to capture and transmit energy to perform work.
If I were to assume a similar story for Hysatas where photovoltaics feed electricity to electrolyze water and a whole new infrastructure for fuel is stood up: What measure would measure and demonstrate the relative efficiency between the two processes?
The finding the biomass to make the methane from is the non-scalable, energy intensive part. You have to collect the biomass, load it on to a truck, ship it around on a truck, and then unload it and dispose of it after it's depleted.
If you only need air, electricity and water to make the synthetic fuel, that's going to be scalable to a civilizational level scale.
The methane has to come from biomass, so this isn't quite closing the loop here on a full solar only process. Pure CO2 and water to synfuels is still wildly energy inefficient.