California has been making great progress replacing electricity generation from fossil fuels with cleaner renewable generation. We are on track to have 33 percent of our electricity come from clean renewable energy by 2020.

However, the strategies that will get us to this milestone are not enough for the next step. To meet new greenhouse gas reduction goals, we need to begin developing the renewable generation that will support a much cleaner electric grid without sacrificing reliability. This is exactly the role for one of California's great resources — geothermal energy.

California has some of the best geothermal resources in the world. It has a proven track record of providing low-carbon reliable power to Californians for more than 50 years. One of the best geothermal areas spans Lake and Sonoma counties. The Geysers geothermal resource area is the largest in the world. In operation since 1960, it provides around 725 megawatts of steady, affordable and clean power to local residents and businesses. When compared with fossil fuel-powered plants, operation of The Geysers helps avoid 2.4 million tons of greenhouse gas emissions annually.

There are two new projects in The Geysers that if built could provide further greenhouse gas reductions of 139,000 to 199,000 tons per year of carbon dioxide. That's no small sum.

While the current system of choosing new renewable power plants has worked so far, it is not designed to get the kind of diversified electric system we need for the future. In particular, it does not assign enough value to the fact that geothermal resources provide reliable power around the clock — regardless of weather or time of day. We need to begin constructing projects that will provide the kind of renewable energy that we know we are going to need in the years ahead.

Senate Bill 1139 would require the state's utilities to buy 500 megawatts of new geothermal generation. This is a small down payment on the future clean electric system Californians want.

In addition to the climate benefits, geothermal energy has enormous economic benefits. Constructing new geothermal projects is labor intensive and requires all types of skilled construction workers. Construction would create around 200 local jobs and feed the local economy during the more than two years it would take to build them.

Calpine Corp. at The Geysers is the largest taxpayer in Sonoma and Lake counties, contributing millions of dollars each year to our local economies. Calpine's two new projects could generate even more steady tax revenue.

Importantly, all the necessary permits for construction have been approved by state and local agencies and project labor agreements for both plants have been executed. Now, it's time for state legislators and regulators to act — and soon, before the permits expire.

As conversations evolve at the state Capitol and the California Public Utilities Commission about the policy reforms needed to achieve energy and environmental goals beyond 2020, I urge them to consider the long-term need for new renewable baseload generation that will support the clean electric system of the future. SB 1139 is a good first step.

<i>Robbie Hunter is president of the State Building and Construction Trades Council of California, which represents 400,000 California construction workers.</i>