I'm not really the type to pipe up and get into an argument when people say things like "there's just not enough sunlight for solar to replace coal" or "I don't by organic because it's fertilized with manure". My instincts tell me that these statements are wrong, but I'll lose the argument every time because I don't have all the facts at my finger tips. I can do research later and refute everything, but it's like coming up with the perfect retort for that bully long after he's gone. The first example came up recently, and I let it go, but I figured this blog gives me a chance to set the record straight (to no one in particular).
Last year, Scientific American published an in-depth article explaining just how we could power the entire country on solar. Granted it would be a huge investment, but it would work. It involves building huge collectors in the southwest and building a new transmission network to get the power where it's needed. One of the problems was how to make solar energy available at night, most storage techniques are untested, expensive, lossy, or all of the above. They propose storing heat in salt domes or something.
Two recent developments will alleviate most of these problems. First, researchers at MIT figured out an efficient way to use solar energy to directly separate water into hydrogen and oxygen. Traditional electrolysis zaps water with a current to pull the molecules apart. This takes far more energy than can be recouped by burning the hydrogen. The new method is much more efficient. Second, Australian researchers figured out how to make fuel cells without platinum. That should reduce the cost of pulling the energy back out of the hydrogen.
Storing energy as hydrogen may also help the transmission issue. I don't know the numbers, but it could be more efficient to build a hydrogen infrastructure rather than transmitting electricity directly.