There is a post on the European Wind Energy Association (EWEA) blog with the following incredibly misleading headline Global wind power and other renewables about to surpass fossil fuels. The details, of course, are considerably different.
What actually happened was that the PEAK capacity total for all sources of energy that are officially classified as “renewable” that was installed in 2009 started to approach the newly installed capacity of all systems designed to burn fossil fuel to supply electricity. The total amount of energy produced by burning fossil fuels still provided more than 80% of the total amount of energy consumed.
This focus on PEAK capacity is rampant in the public relations efforts from the renewable energy industry, especially the wind and solar components of that industry. They like to minimize the fact that power is most useful when it can be applied when and where people need it. Power sources whose output is controlled by the weather and are best located in places that are a long distance from where people live are simply not equivalent to power sources that can be controlled by human operators and located near customers.
A regular reader provided me a link to a useful site provided by Tucson Electric Power that provides a glimpse of the real output from a system described as a “4.6 MWe” solar power plant. The photos and dashboard style display are useful and should cause some sober reflection among enthusiasts.
This 44 acre installation, located in an open desert at high elevation with excellent solar insolation, produces about 7,800 MW-hours of electricity each year. Since there are 8760 hours in each year and the system peak capacity is 4.6 MWe, that means that the average annual capacity factor is just 7800/4.6 x 8760 = 19%. There is also an interesting quote about the facility in a paper titled Five Years of Operating Experience at the Springerville PV Generating Plant:
The PV Generating Plant is located next to the coal-fired Springerville Generating Station and is intertied to the same transmission line that feeds power back to Tucson. TEP is observing that PV generating intermittencies associated with short timescale events, such as cloud passage and storms, are in fact swinging the controls of a 420 MW coal fired unit at the generating station. These impacts bring into question the capacity value of solar in the utility plant operations and emphasize the need to stabilize PV power output, perhaps through storage or inverter modifications, in the utility environment.
In other words, take the pronouncements of the renewable energy industry with regard to their capacity additions with a great deal of skepticism. Peak capacity has little or no meaning in terms of providing the kind of reliable electricity that customers demand from their power suppliers.