Mark - Those routes to making methane are actually really good ideas and as we know, all of the waste treatment plants have been making biogas by that method for many years. One of the newer ideas is to culture biofuels or bioenergy crops or even algae, feed them into a digester and make methane. The thing about hydrogen is firstly that you have a carbon-free economy, but also that when you look at the biochemistry and the energy pathways involved, instead of making those algae and then turning them into methane, if you can make hydrogen directly, that'll be more efficient, and you'll effectively get more energy from a certain amount of land which is gathering a certain amount of sunlight.