Gov. Jerry Brown is poised to give California the most aggressive standard in the country for renewable energy, requiring that one-third of utilities’ power comes from solar cells, windmills or other alternative sources within 10 years.

The Democratic governor is expected to sign the legislation Tuesday at a solar plant in the San Francisco Bay area, accompanied by U.S. Energy Secretary Steven Chu.

Supporters say the standard will mean cleaner air and lead to less reliance on foreign oil. They also say it will assure investors that demand for renewable energy is strong and will create an environment that promotes job growth in the industry.

Some critics say the move will drive up California’s already-high energy costs, hurting companies’ competitiveness.