It’s simple: relying on oil, coal, and natural gas for the bulk of our energy needs is ultimately a losing proposition. Fossil fuels will peak and run out someday; they’re already becoming less efficient and even more environmentally harmful to extract. In the meantime, burning them emits so many pollutants and causes so many other problems (global warming, air pollution, water pollution, devastation at extraction sites, destruction of habitat, oil spills, etc.) that we need to diversify our sources of energy as soon as possible.
There are a wide variety of alternative and renewable sources of energy (solar, wind, biofuels, geothermal, hydroelectric, etc.). The main challenges are to make renewables cost-effective and to minimize unintended consequences (such as solar vs. desert habitat; windfarms vs. birds, hydro power vs. river wildlife, and biofuels vs. food production). Solving these problems calls for a major investment into green jobs, including training a workforce for these jobs (see green jobs). In any case, weaning ourselves off fossil fuels will help avoid massive societal disruptions and will have major benefits for our air quality, our water quality, and reducing emissions that contribute to global warming.
California's Renewables Portfolio Standard (RPS) is the most ambitious renewable energy standard in the country. The RPS program required electric corporations to increase procurement from eligible renewable energy resources by at least 1% of their retail sales annually, until they reached 20% by 2010. Governor Jerry Brown kept his campaign promise to make the requirement even more rigorous when he signed legislation in 2011 that requires the companies to achieve 33% RPS by 2020.
Prior to that, despite proclamations (and an executive order) in support of a 33% RPS by 2020, former Governor Schwarzenegger vetoed two bills in 2010, SB 14 (Simitian) and AB 64 (Krekorian), which would have established the 33% target as state law. Fortunately, Governor Jerry Brown signed the 33% requirement into law the following year.