It's not 40% efficient at turning CO2 in the atmosphere into fuel (If we had a technology that could do that, I would not worry at all about climate change), it's 40% efficient at turning highly concentrated CO2, from say, the chimney stack of a coal power plant into fuel.
Which is what makes it nearly-useless. The solution to energy generation that emits CO2 is not trying to recover it from the chimney. The solution is eliminating it. This can solve the problem of concentrated CO2 emitted as an industrial byproduct of non-energy-generating chemical processes, but that is not a major contributor [1] to our carbon emissions.
[1] Cement manufacturing is often pointed to as a major CO2 emitter... Yet it is responsible for ~1.5% of emissions in the US (~8% in China). So, you could make a bit of a dent in a small fraction of our emissions, but it doesn't come remotely close to solving the overall emissions problem.
I disagree with the idea that we shouldn't build capturing innovations on top of chimney CO2 emissions just because we need to eliminate those chimney emissions. Yes, we should reduce chimney emissions. But it appears that isn't going to be as easy as we'd like. It's why we're seeing various European countries turning on their coal plants again because Russia turned off the gas. We really need to have these capturing innovations that happen at the chimney too.
I don't see us succeeding in reducing our dependency on fossil fuels in the near future. We can achieve some reductions at national level. But these fossil fuels are simply going to find a customer somewhere else. It would be better if the West can provide cheap sustainable fuels or export/sponsor CO2 capturing solutions for foreign countries.
