What are the best short and long term investments for alternative energies?

So far I've researched Fuel Cell Energies, which partly runs on natural gas. I've also researched Solar Powered Energies which as we know relies on the Sun...What are some good long term stocks or funds within alt. energies? Do you think alt. energies are a promising investment? I'd feel great knowing I'm helping invest into a Go Green company while making some $.

I don't really know what the best investment is but don't forget about wind power. I believe one of the leading corp.'s on that is Invenergy if you want to look them up.

The main three are Solar Energy, Wind and Biofuels and all have there own problems.

Solar is very expensive but is expected to come down in price over the next 6-7 years.

Wind Power although clean, enviromentalists do not like them but a large amount of energy is supplied by them (off the top of my head, I think its upto 30% in CA).

Biofuels would appear to be the best on the face of it but if we use corn/sugar etc to power our cars etc, the prices of our food goes up. Also, its not possible to grow enough to supply the required energy for the world.

In my opinion these are all future sources of energy and money can be made in the long term. However, I would suggest you invest in the underlying materials which are required to make these clean energies.

For example invest in electronic companies which work on the PV's for Solar, metal companies for making the wind terbines etc.