Intermittent sources of power production such as wind, solar, and bio-gas are frequently criticized as being too intermittent and unreliable to be of value to the electrical grid. The argument is often put forward that every megawatt or wind energy capacity has to be backed up with another megawatt of production capacity somewhere else on the grid so power is available 7-24.
On one level, that criticism ignores that the direct variable operating cost of wind and solar energy is nearly zero unlike thermal energy plants like gas, coal or nuclear which must pay for fuel to produce energy.
In a recent blog, Paul Gipe at Wind Works has taken another approach at looking at the reliability – redundancy comparison between wind and nuclear energy. In his analysis, he looks at availability levels over longer periods to determine how much extra capacity has to be available in the grid to deal with planned and unplanned outages of nuclear plants. After conducting the comparison, he makes the following observation:
Critics of wind energy often charge that wind energy is too “unreliable” to generate a large portion of a nation’s electricity and suggest that base load needs “reliable” sources of generation such as nuclear power. While wind is a “variable” resource, that is, the wind doesn’t always blow and when it does it doesn’t always blow at the same strength, wind is far more reliable than the critics charge. In fact, wind is fairly predictable on long time horizons, especially from one year to the next.
In contrast, nuclear power is “reliable” until it isn’t as the units at the Fukushima nuclear power plant so dramatically demonstrate.
While Paul’s analysis would be more convincing if he was able to document available versus non-available operating statistics instead of total power production data, the approach of looking at availability versus redundancy levels over a period of years is interesting. The next logical step in this technique is to look at comparable figures for a single coal or gas turbine unit.