Vinod Khosla's investment activity in renewable energy startups is very deep. While speaking at the Management of Technology Lecture Series earlier this month at the Haas School of Business in Berkeley, he gave the most detailed look yet at Khosla Ventures' investment portfolio.

Most of the companies are based around the general themes of making coal, materials, efficiency and oil more efficient. Then, he further refines them by grouping his investments according to the type of energy that the portfolio companies are trying to improve or harness. Here are the specific investment themes and companies that fall into each category:

1) Cellulosic - Mascoma, Celunol, Range Fuels, 1 stealth startup

2) Future Fuels - LS9, Gevo, Amyris Biotechnologies, Coskata Energy

3) Efficiency - Transonic Combustion, GroupIV Semiconductor, 1 stealth startup

4) Homes - Living Homes, Global Homes

5) Natural Gas - Great Point Energy

6) Solar - Stion, Ausra

7) Tools - Nanostellar, Codon Devices, Praj

8) Water - 2 stealth startup

9) Plastic - Segetis, 1 stealth startup

10) Corn/Sugar Fuels - Altra, Cilion, Hawaii Bio

Water startups are particularly attractive to Khosla because it's such a big problem. And he said solar startups can help solve climate change and provide a return now that the cost of coal has risen. Biodiesel startups are notably missing from the list. Khosla couldn't help taking a few shots at that sector. He said, "Willie Nelson loves it but he hasn't thought about scaleability."

The list of startups provides far more information about Khosla's efforts in this area than has been revealed before. Khosla's web site only lists two cleantech startups. And a few others such as Altria and Cilion have been publicly announced listing Khosla Ventures as an investor.

Considering the sheer number of companies and the fact that many require a lot of capital to grow, it's incredible that Khosla's fund is comprised only of his own money. Skeptics note that exits may be a long way out. With venture capital logic, though, Khosla seems to be betting that it will only take one or more major hits to cover the costs of the ones that don't make it big.

Tags: venture+capital, vc, vinod+khosla, khosla+ventures.