Californians are relatively thrifty when it comes to electricity consumption, using less on a per-capita basis than residents of any other state. The average Californian consumed 7,032 kilowatt-hours of power in 2005, according to the California Energy Commission. That's not much more than half the U.S. average of 12,347 kilowatt-hours.

Still, population growth of nearly half a million people per year is driving an increase in overall electricity demand, prompting the state's utilities to search for new energy sources. In the past, the solution was relatively straightforward: Build a generating plant, most likely powered by natural gas to comply with the state's strict air-quality standards, and wire it to the grid.

Carbon-based fuels, however, are decidedly out of favor in California in these days of heightened concern about global warming, and new laws are forcing providers to explore greener energy alternatives. But as utilities try to find and tap environmentally superior electricity sources, they are finding that even "green" power development often has a price tag environmentalists and their supporters are unwilling to pay — namely, the degradation of parks and natural areas.

Under a law passed last year — SB107 by Sen. Joe Simitian (D-Palo Alto) and Senate President Pro Tem Don Perata (D-Oakland) — California must obtain 20% of its electricity from renewable energy sources by December 31, 2010. The law defines those sources as biomass, solar thermal, photovoltaic, wind, geothermal, fuel cells using renewable fuels, small hydroelectric generation of 30 megawatts or less, digester gas, municipal solid waste conversion, landfill gas, ocean wave, ocean thermal, or tidal current.

Qualifying generating plants need not be located in the state. In fact, they don't even have to be located in this country, although the law stipulates that they must be connected to the grid serving the Western United States.

The mandates set by SB107 are part of a broader push in California to address the greenhouse gas emissions that contribute to global climate change. The most far-reaching of those is AB32, also signed into law last year. The statute requires the California Air Resources Board to develop regulations and market mechanisms to reduce California's greenhouse gas emissions by 25% by 2020.

Renewable electricity sources currently provide 11% of California's power. The Simitian-Perata bill requires the state nearly to double that over the next three years. This accelerated push for greener electricity has set off a small stampede as utilities scramble to locate potential generating sites and link them to the grid.

Of the state's five major utilities, only Southern California Edison (SCE) — which derives 16% of its electricity from renewables — is anywhere close to meeting the SB107 mandate. Pacific Gas & Electric, serving Northern California, is next at 13%, followed closely by the Sacramento Municipal Utility District at 12%. At the back of the pack are San Diego Gas & Electric (SDG&E) at 8%, and the Los Angeles Department of Water and Power at 6%.

So far, most of the utilities' efforts at providing green power have focused on transmission lines, long the Achilles heel of the statewide power grid and assuming even greater importance as renewables move to the forefront.

Unlike the natural gas-fired generators that historically have provided the biggest share of California's electricity, power plants using many of the most promising renewable technologies cannot be sited just anywhere. Wind power, for example, can only be generated where there's lots of steady wind. Solar cells work best in the deserts and hot valleys of the interior. Small hydro plants require running water. Geothermal requires underground reservoirs of hot water or at least hot rocks.

Utilities gambling on renewables must, in effect, go find the power — typically in relatively remote rural areas — and obtain regulatory permission to install transmission lines connecting the new generating sites to the state's major urban areas, where most customers live.

Perhaps the most contentious "green" power proposal currently before regulators is the Sunrise Powerlink, a high-voltage transmission line proposed by SDG&E. Portrayed by its proponents as a way to tap "clean, renewable energy sources such as wind, solar and geothermal" in the Imperial Valley and eastern San Diego County, the 150-mile transmission line would allow SDG&E to import 1,000 megawatts of electricity, enough to serve about 650,000 homes.

The preferred transmission corridor, however, would cut through several prized natural areas, including Anza-Borrego Desert State Park, a sprawling swath of arid canyons, mountains and valleys that are popular with recreational users and home to numerous protected species.

Although SDG&E has proposed installing the new line along an existing utility corridor, the project would require replacing a series of 50-foot wooden power poles with steel towers up to three times as tall. Consequently, the proposal has drawn opposition from the Sierra Club, the Center for Biological Diversity and other environmental advocates struck by the incongruity of a "clean" energy project that would disrupt a relatively pristine landscape. A draft environmental study of the Sunrise Powerlink project is due for release in August.

Regulators are also reviewing a project involving a new hydropower plant in San Diego County that would connect via a new transmission line to the systems of SDG&E and SCE. The project, a joint undertaking of the Nevada Hydro Company and the Elsinore Valley Municipal Water District, would involve construction of a 180-foot dam, creating a storage reservoir that would be filled with water pumped uphill from Lake Elsinore. The water behind the dam would be released during the day to generate electricity and then be pumped back up at night.

Technically, the project doesn't fit the SB107 renewable guidelines because, at 500 megawatts, it's not a "small" hydro project. But it would still be a climate-friendly power source. Nevertheless, it has drawn fierce environmental opposition because the new reservoir would drown a canyon popular with hikers in the Cleveland National Forest.

Another project receiving scrutiny is a Southern California Edison project that involves a transmission line needed to move electricity from a new wind farm in the Tehachapi Mountains to the utility's existing distribution system. The Public Utilities Commission recently approved the project.

The wind project is being developed in the blustery passes and mountains of eastern Kern County by Mojave-based Oak Creek Energy Systems and Allco Finance Group of Australia. SCE signed a contract last year to buy 1,500 megawatts of electricity from the project, which the companies say will be the world's largest wind power generator.

David Hogan, Center for Biological Diversity, (619) 473-8217.
SDG&E's Sunrise Powerlink project:
SCE's, Tehachapi project: