Pacific Gas & Electric (NYSE:PCG), which is primarily engaged in the business of electricity generation and natural gas distribution, might not strike you as a natural way to play the growing interest in "cleantech" investments, but I believe a compelling argument can be made along those very lines.

To wit, I've discussed before how the company was seeking to plug the pesky problem of storing excess electricity by demonstrating how a converted Toyota (NYSE:TM) Prius could be recharged at night when the cost of electricity was low and then used to power a home or office during the day when the cost of electricity was high.

Since that time, I've discovered no fewer than six separate renewable energy projects in which PG&E is currently engaged. Late last year, the company received approval for a 120-megawatt geothermal facility in Oregon. In January, it began receiving an estimated 38 megawatts of wind power from Buena Vista Energy, and the following month it facilitated a deal for Starwood Hotels & Resorts Worldwide (NYSE:HOT) to install a fuel cell power plant from FuelCell Energy (NASDAQ:FCEL) to supply nearly 100% of the energy for the Westin Airport Hotel in San Francisco.

PG&E is also pursuing two biomass-to-energy projects in Chowchilla and El Nido, Calif.; installing solar cells to power the San Francisco Giants' baseball stadium; and investigating the idea of using wave power off the coast of northern California to generate electricity.

In total, the utility now supplies 13% of its energy from renewable resources, and it expects that to increase to 20% by 2010. When one considers that an additional 46% of the company's electricity generation comes from nuclear and hydroelectric power sources, this means that well over half of its electricity produces no carbon dioxide. For a utility company, that's darn good.

From my perspective, such numbers, in combination with management's obvious commitment to renewable energy, make PG&E a legitimate cleantech investment.

PG&E carries a sterling five-star rating in Motley Fools CAPS. Of the 50 people who have given it a rating, 49 have rated it as an "outperform" as compared to only one underperform. Among All-Stars, it's batting a perfect 100%.

Fool contributor Jack Uldrich does not own stock in any of the companies mentioned in this article.