Where is My Artificial Tree?

I went through a phase in my childhood when I was going to be a great inventor. One of the things I imagined myself inventing was an artificial leaf, a system that would mimic the energy harvesting power of photosynthesis. I must have read in some children's science book, or perhaps in National Geographic, that this was a great goal for science that would revolutionize human society.

The good news is that we now have artificial leaves that carry out photosynthesis. The bad news is that this long-sought invention is making no difference whatsoever. One version was developed by GE scientist Daniel Nocera, and the company has been touting it in their feel-good propaganda for more than a year:

Such artificial-leaf optimism could also be found a year ago in a Los Angeles Times article that held the artificial leaf “could create enough clean fuel to power a home for a day in developing countries.” And the year before that, in The New Yorker, where Mr. Nocera said the artificial leaf would “turn a home into ‘a self-sufficient power station.’ ” Or go back one more year, to the pages of The New York Times, where Mr. Nocera said, “Our goal is to make each home its own power station.”

So, all right already. Where’s my power station?

It's the same story we have heard so many times in the field of alternative energy. From fuel cells to electric cars to natural gas from algae, we keep hearing about wonderful technical breakthroughs, but we still get most of our energy from fossil fuels.

The first step in photosynthesis is the splitting of a water molecule to make oxygen and hydrogen. Nocera's chip uses catalysts and sunlight to achieve this same result. In a cell, the hydrogen is then reacted with carbon dioxide to make sugar. Nocera's chip simply pumps out hydrogen and oxygen. The process seems to work efficiently enough to be cost-competitive with natural gas or photovoltaic cells, although it's hard to know how well it would scale up. So if you installed a panel of these in your house, you would then have a steady supply of hydrogen gas.

Have any use for hydrogen gas?

That's the problem. To make use of this hydrogen, you would also need to install a bank of fuel cells to turn it into electricity, and either find a way to hook those fuel cells up to the grid or attach them directly to your appliances, and so on, all of which is doable but far from simple. The technology may be great, but the infrastructure to make good use of it does not exist. And that is a big hill to cross.