You can power laptops - and, potentially cars - using hydrogen extracted from water. The trouble is that it takes a lot of electricity. A simpler way would be to do it naturally, using enzymes - proteins which catalyse reactions - and bacteria. These do exist: certain green algae and "cyanobacteria" can split water using photosynthesis to produce molecular hydrogen.
But to create a generation of cars that would run on water with some sludge in the back, we need to learn how to design our own bacteria and enzymes that can co-opt natural processes for our ends.
Natural hydrogen-producing enzymes are complex, often using metal atoms to help them work. "For many of the enzymes related to energy production, people have no idea how they are actually organised," says Giovanna Ghirlanda, a protein-design researcher at the University of Arizona. In some cases, no one knows where the metal atoms lie within the protein, she says.
Natural enzymes won't work too well in future fuel cells; they need to be modified, as the best hydrogen producers are poisoned by oxygen. "But oxygen is one of the main products of photosynthesis," says Professor Alfonso Jaramillo of the Ecole Polytechnic, near Paris.
Some researchers are trying to tweak the enzymes to make them less sensitive to oxygen, but with limited success. As a part of the EU-funded BioModularH2 project, Jaramillo's team is using a different approach: stick with the natural enzyme and engineer another set of proteins that take oxygen out of the cell before it can do any harm. These hydrogen producers are longer-term options: it may take 10 years to get to a prototype, says Jaramillo.
You can read the rest at the Guardian.