We've got plenty of CO2 (carbon dioxide), so much as a matter of fact that it may be affecting the climate by blocking the dispersion of heat from the Earth into the space. CO2 is a by product of most industrial activities, of energy transformation (like converting energy from fossil fuels into electricity or into mechanical energy in a combustion engine), as well as industrial livestock production.
It would be good to be able to re-use all this CO2. By adding 3 molecules of H2, as shown in the figure you can actually produce methanol (CH3OH) and water (H2O). Methanol, a kind of alcohol, can be used as fuel in cars (with an appropriately tweaked engine), so one can imagine a car running on methanol, producing CO2 and reusing the CO2 by adding H2 to refill the tank! Looks like a "perpetual motion", which of course cannot be true. Well, it is not, since at the very least you need to add H2.
However, it goes beyond adding H2. The CO2 molecule is quite stable on its own and does not combine willingly with others so even if you provide H2 the time it will take to create methanol will be too long. What you need is a way to accelerate the process. And this is what researchers at the Brookhaven National Laboratory have managed to do.
They have been able to create a catalyst using copper and cerium nano particle but what is interesting, at least that is what pushed me to write a post, is the way they came to their discovery. They observed copper nano particles (already used along with zinc oxide in today's industrial processes) as they interact with CO2 and H2 using spectroscopic techniques (see the video clip) and then they used a supercomputer to model the process. It was clear from the modelling and the observation that the most effective catalytic effect takes place at the boundary between copper and ceria oxide. Based on this studies they designed a system to create these conditions and effectively they observed a catalytic reaction 1,000 times faster than the one occurring when only copper is used (and this is 90 times faster than the current industrial processes to produce methanol out of CO2 and H2).
This really opens up a way to reuse the CO2 from cars' emission, although you will need to have H2, and this in turns have to be produced through electrolyses. Hence, there is no free linch but the nice thing is that we use renewable energy sources for the electrolytic process, heck we can effectively reduce the CO2 footprint.