FUTURE PROOF

Research into substitute fuels is great, but we need to be cutting carbon now, says Paul

- Paul Horrell

"Sustainable" petrol seems like a magical idea. Find a way to remove CO₂ from the atmosphere, then turn that captured carbon into petrol by adding hydrogen to form the hydrocarbon molecules of petrol. So when you combust it, you're merely sending the CO₂ back up, rather than creating CO₂ from what has been trapped underground for millennia. It's a net zero closed loop. And it works with the all petrol cars and fuel stations we already have. Huzzah!

Whence that captured carbon? You can let nature do it. Plants absorb CO₂ as they grow. Now take that plant material and turn it into petrol - not simple, but doable. Great. Except everyone agrees it'd be a rotten idea to use plants that would be used to feed people and divert them into powering cars, or to grow the plants on slashed rainforest land. Both have happened. So the trick is to manufacture from sources of plant material that don't constrain food supply - aka second-generation biofuel.