Question: Are there other ways to make clean renewable fuel for the future?

Katherine Haxton answered on 18 Mar 2012:

The best source of energy on the planet is the sun and it’s free and totally renewable. If scientists can come up with clever ways to collect more of that energy, we should be able to make clean renewable fuels or get the energy more directly. There are several options but one of the most interesting uses something that goes on all around us, billions of times each day: photosynthesis. Plants are incredibly good at using the sun’s energy to produce fuel, turning carbon dioxide and water into sugars. So biodiesel from land crops or Daphne’s microalgae could be an awesome fuel. The problem with a fuel like that is that if we wanted to produce electricity, we’d probably have to burn it to produce heat, to heat water to turn a turbine that generates electricity. The burning would produce carbon dioxide and water again so it might not be as clean as we hope.

Photosynthesis uses chlorophyll, a molecule in plants and lots of chemists are trying to make more efficient chlorophyll type molecules to use in solar cells to directly convert sunlight into electricity without producing more carbon dioxide. It’s called ‘artificial photosynthesis’. Sunlight might also be used to break water molecules apart into hydrogen and oxygen. The hydrogen can be used as a fuel and will only produce water when it burns – no carbon dioxide so it’s a bit cleaner. Chemically that’s quite difficult as water is pretty happy as water and needs quite a lot of energy to break up.