Converting water and CO2 to hydrocarbons is not new...but...it takes energy and a lot of it. The reverse of this reaction is very widely used in industry to make hydrogen via steam reforming and the water gas shift reaction. TFA says that the petrol synthesizers are using electricity from the national grid but does not bother us with any details of how much electricity they are using. It is unquestionably a lot of electricity, though. So why isn't this a great discovery? I mean, it takes electricity and converts it into a hydrocarbon fuel that we can easily store and use, right? Well, this process is certainly a large net energy consumer in that the energy in the synthesized petrol is only a small fraction of the electrical energy used to make it in the first place. This means that we would need to generate huge quantities of electricity to produce the petrol. The very reason that we extract hydrocarbons (oil, gas, and coal) out of the ground in the first place is to obtain the energy contained within them so a process that consumes a lot of electrical energy to reproduce a small fraction of the original hydrocarbon energy used to create the electricity is...ridiculous...and would accelerate the generation of carbon dioxide. Now, if we lived in a world that did not generate electricity from hydrocarbon fuel directly or if we had large quantities of electrical energy that was unused and available from, say, wind turbines or tidal generators, then we could consider a process to create hydrocarbon fuel from carbon dioxide and electricity...but that is not our world now or in the forseeable future. Electricity generation from wind turbines, solar energy, and the like is expensive, heavily subsidized, and would result in extremely expensive hydrocarbon fuel if it were used in a process such as that described in the article.