"Many high-tech companies understand they have a role to play in bringing the next generation of innovation by supporting, promoting, creating and bringing to market technologies that will help the world meet its energy and communications needs," said SSV director Margaret Bruce.

SSV members already reduced emissions of carbon dioxide by 12 percent between 2000 and 2005. The group has set a goal of reducing that figure to 20 percent below 1990 levels over the next four years.

The target is even more ambitious than goals set out by authorities in California, which has the toughest clean-air laws in the United States.

"The main motivation is the risks and opportunities linked to the environment, which are financial drivers," Bruce added, emphasising that fluctuating costs of fossil fuel-based energy made alternative energy an attractive business proposition.

"It's really difficult to do business when you can't predict how much your energy is going to cost," she said. "It becomes important to be as efficient and as secure in terms of energy use as possible."

Many companies are looking to solar power to provide the alternative. In April, Microsoft installed 2,288 solar panels at its Silicon Valley office.

"Over the next 30 years, the solar-generated electricity will reduce emissions of carbon dioxide by more than 4,000 tonnes," Microsoft said in a statement.

Another IT giant, Google, has followed suit, announcing plans to install solar panels on its headquarters in Mountain View. The company hopes they will provide 1.6 megawatts of energy, helping to meet around a third of the complex's power demands.

"If as a by-product of this installation we dispel the myth that you can't be green and profitable at the same time, then that is also a major benefit," said David Radcliffe, Google's vice-president of real estate.

"In addition, this investment will pay for itself within five-10 years, which means that the clean electricity that is produced after that period of time will be completely free."

The "greening" of Silicon Valley has led to a surge in business for alternative energy providers, with solar panel manufacturers leading the way. One of them, Nanosolar, plans to build the largest solar panel factory in the world in Silicon Valley.

"Silicon Valley is the place to bring smart people together to start investigating on innovating technologies," said Nanosolar chief executive Martin Roscheisen. "Electricity has become a lot more expensive in the recent years, so it's an opportunity for green technologies to be more competitive."

California has some way to go. Despite its tough clean-air legislation it was second only to Texas for greenhouse gas emissions in the United States in 2004.

However, authorities point to a modest increase in emissions of 12 percent between 1990 and 2004, at a time when California's economy surged by 83 percent, as a reason for optimism about meeting future reductions.

A report from the California Energy Commission said the figures showed that increases in emissions and economic growth were not inextricably linked.

Related Links
Sustainable Silicon Valley
Our Polluted World and Cleaning It Up