Fuels from Sunlight: Converting Solar Energy

This was another in the series of public talks at Stanford University tonight. Professor Thomas Jaramillo made an eloquent case for:

1. Fossil fuels (high energy density, easy to transport, stable, inexpensive)
2. Converting sunlight directly to fuels that meet some of the above criteria without converting to electricity first. (fossil fuels are easy to store)

How do they do it?

1. Use energy in photons to move generate free electrons (and "holes").
2. Use these electrons and photons to break down water into hydrogen and oxygen. This hydrogen can be used as fuel. They can also be used to create hydrocarbons from water by pulling carbon di oxide from the air.

Next level of detail

1. Create a semiconductor cell to generate a voltage difference when light falls on it. This voltage difference is equal to the energy absorbed from the photons.
   
2. If not possible through one cell, this can be achieved through two - the anode cell and the cathode cell, each one generating some potential difference.
3. The charges are then transported to the edge of the semiconductor.
4. In the presence of a catalyst these charges convert the medium (water), in combination with the atmosphere to fuel.

The process works today, but is very expensive. They are trying to make it low-cost. Interesting, isn't it. If this is effective, you no longer have to worry about changing the entire transportation infrastructure. The same cars, the same factories, everything will work. And, the system will just capture carbondioxide that it releases.

The only thing we need to be careful of is - to do nothing for the environment while waiting for this solution to be cost-efficient.