The CO2 in the Martian Atmosphere will be used to produce methane by the so-called Sabatier process (discovered by the French chemist Paul Sabatier in the nineteenth century). The reaction converts carbon dioxide with hydrogen at elevated temperatures into methane and water (Stephen J. Hoffman, David I. Kaplan,1997):
4H2 + CO2 ---> CH4 + 2H2O
Since no hydrogen is found in the Martian atmosphere, the hydrogen has to be imported from Earth or from the Moon and NEOs. CH4/O2 rocket propellant only consists of 16% hydrogen by mass. Therefore, the reduction in mass that has to be brought from Earth to Mars is still substantial. A quick calculation shows that about 0.222 kg of H2 and 1.222 kg of CO2 are needed to produce 1 kg of water and 0.444 kg of CH4."
See, they take seawater, and using copious amounts of electricity, turn it into HCl and NaSO4.
Now this nice gentleman thinks he can take CO2 and combine it with the HCl, to create the light petroleum products like butane.
Isn't this a bit like making a perpetual motion machine?
Of course it does. If it didn't the 2nd Law of Thermodynamics would have been broken. You do know that the making of gasoline, diesel fuel, etc., also all require more energy than the fuel supplies, don't you?