Thus far, the state is behind the curve, so to speak. For 2007 data, renewables comprised 11.8 percent of total power sales. That indicates that another 9.2 percent must be generated in only 3 years. The 2007 number was 35,500 Giga-Watt-hours for renewables generation. Rounding things off, it appears that another 33,000 GWH must be generated in 3 years, or roughly 11,000 GWH per year added. The issue is to determine how much MW of capacity to install in order to achieve the 11,000 GWH per year. That is not an easy problem to solve, because hours spent generating depends on the technology employed. For example, geothermal and biomass plants can run very close to 100 percent, but wind and solar run along 24 to 30 percent of rated capacity.
With the current mix of renewable technologies, the capacity factor is roughly 67 percent, meaning that, on average, renewable power plants generate roughly 16 hours per day, every day. However, the big plants that have been approved for construction are, for the most part, solar and wind plants. As stated above, their capacity factors are around 25 percent, roughly 6 hours per day. Solar can run a bit longer with energy storage systems, some reports indicate 12 to 15 hours per day. The capital cost required to store heat and generate after sundown is much higher, though.
So, just using all solar and wind technologies, and 25 percent capacity factor, the MW of new installed capacity can be found that produces 11,000 GWH of power in one year. The result is a bit more than 5,000 MW installed each year. For three years of 2008, 2009, and 2010, that is three times greater, or 15,000 MW total to be installed.
From the California Energy Commission website of approved and pending plant permits, we see that only 2,670 MW are approved for installation in 2009 and 2010, which is to generate 9,150 GWH power. In 2008, 1,190 MW were installed, which generated 6,500 GWH.
With 15,000 MW required, and roughly 3,800 of that installed or under construction with a likelihood of starting up before December 2010, the state is only short by 11,200 MW.
One thing is certain: the 20 percent goal by 2010 is not going to happen.
Roger E. Sowell, Esq.