Hi HN! I’m Rob, Founder of Prometheus. We’re removing CO2 from the air and turning it gasoline, diesel, and jet fuel. Since we use zero-carbon electricity from sources like solar and wind to make our fuel, there are no net CO2 emissions when you use it. An article about us came up on HN recently and people seemed interested ( https://news.ycombinator.com/item?id=19792412 ), so we thought it would be good to try to answer some of the questions we saw there and try to dive in some more to any questions that follow! The only inputs to make the fuel are CO2 and water (both from the air) and electricity. The only outputs are fuel and oxygen. One way to think about it is that making fuel is reverse combustion. The process isn’t super efficient (we expect 50-60% overall efficiency at maturity), but it turns out that doesn’t matter as long as the electricity is zero carbon and low cost. If the cost of our equipment is also low, then we believe we can not only make zero carbon fuel, but actua...