Renewables winning the energy race

The Guardian, Wednesday 16 September 2009
If I am travelling down an "irrational" road to renewables, as Richard Phillips implies (Letters, 11 September), then I am not alone. Last year, solar PV generation capacity grew by 70% around the world, wind power by 29% and solar hot water increased by 15%. By 2008, renewables represented more than 50% of total added generation capacity in both the US and Europe, ie more new renewables capacity was installed than new capacity for gas, coal, oil, and nuclear combined; with no emissions, no wastes and no security issues to worry about – and no worries about fuel running out, or increasing in price.
It's true the energy available from some renewable sources, like wind, varies over time, but we already have to have backup capacity for other plants (including for nuclear plants), which is also used to deal with the daily energy demand peaks. With variable renewables on the grid, these backup plants have to be used a bit more often, adding a small extra cost and, if they are fossil-fuelled, reducing the amount of emissions saved very slightly. But hydro can also be used as backup, and increasingly, so can other types of non-variable renewable source, including biomass and geothermal energy.
If we to have a large amount of nuclear on the grid and the planned large wind-power input, then during low-energy demand periods – particularly at night in summer – we will have more electricity than needed, and one or other will have to give way. Since the output from nuclear plants cannot be varied easily and regularly without economic and operational penalties, we would have to curtail the wind output. How rational is that?
Professor David Elliott
The Open University