The California Public Utilities Commission voted Thursday to approve a controversial transmission line project that aims to bring renewable power from the state's southeastern corner to San Diego.

The decision gave the San Diego Gas & Electric Co. (SDG&E) the go ahead to build the Sunrise Powerlink Transmission Project, which will likely cost roughly $1.9 billion and stretch 123 miles from Imperial County to the coast.

The powerline is set to start operating in 2012, Reuters reported.

The 4-1 vote also capped a three-year contentious public debate over a host of environmental and economic issues. SDG&E said the transmission line is necessary for it to meet the state's renewable energy mandate, which requires utilities to get 20 percent of their electricity from renewable sources such as solar and wind by 2010, and increase the mix to 33 percent by 2020.

The transmission will benefit a host of renewable energy developers in the desert, including Stirling Energy Systems, which is constructing a 900-megawatt solar power plant.

Critics questioned whether SDG&E would build the project only to move largely non-renewable power. They also said the project is too expensive, particularly when its cost will eventually be passed on to ratepayers of three large investor-owned utilities such as Pacific Gas and Electric Co., as well as some smaller ones.

The project is a harbinger of what's to come in California and the rest of the country as more electric service companies aim to build transmission lines to bring solar, wind and other renewable power to cities.

Large solar and wind farms are being developed in remote areas, yet the existing electric grid in the country is old and insufficient to ferry the electricity to towns and cities (see Texas Wind Farms Paying People to Take Power).

Utilities and many renewable energy advocates, such as Al Gore, have championed upgrading and building new transmissions to replace the United States' aging electric grid. To do so could cost $900 billion by 2030, according to the Brattle Group (see National Grid: Dream or Reality? and Al Gore Sets Energy Goal).

The commission had three proposed decisions to choose from. The first proposal, by an administrative law judge, would have denied the project. The judge said SDG&E doesn't need the line to meet the state's renewable energy mandate, and it would cause extensive environmental damage. SDG&E initially proposed building the transmission line through the Anza-Borrego Desert State Park.

The second proposal, coming from commissioner Dian Grueneich, would've allowed the utility to build the line on an alternative route that doesn't go through public or American Indian land. But she wanted SDG&E to agree in writing to use the line mostly for transporting renewable energy.

SDG&E's CEO Debra Reed said in one of the previous meetings that the utility wouldn't sign such an agreement.

The commissioners ended up choosing the third proposal that was put forth by commission president Michael Peevey. Peevey wanted to build the Sunrise project without conditions proposed by Grueneich.