Wednesday, 23 March 2016

Renewable Energy Intermittency

In my arguments below, I don't assume wind can't supply 'baseload', but I do assume extra dispatchable plant is required when wind and/or solar don't deliver. This intermittency can be daily, seasonal or weather dependent.

Solar fails at night, on cloudy days, when it snows or dust storms blow. The further away from the equator, the bigger the problem with intermittency. Britain lies at 51° to 59° latitude. We get at least 6 times more solar in summer than winter. Britain also faces peak demand of about 55GWe in winter (about twice the minimum summer demand) We have very short deep mid-winter days with the sun low on the horizon. This makes solar a particularly bad idea for Britain because we'd need to overbuild 8 to 10 times to get the solar power we'd need in winter. In practice, in winter, solar provides very little for Britain. Germany is not a lot better (w.r.t. latitude) yet poor Germany now has about 40GWe of solar capacity.

Wind fails on windless days and may be curtailed on windy days. So wind never matches its nameplate capacity. Historically British wind capacity utilization averages 28% of nameplate (23% onshore, and 33% for offshore). In practice we've often seen wind capacity fall to just 1% (over several hours), less than 5% (over days); less than 10% (over many weeks).

Solar and wind intermittency cause many problems:

  1. Cost of coping with intermittency. Extra electrical plant is required to generate when solar and/or wind plant produce low or no electricity. This extra plant costs additional money to build and operate. Today this must be fossil fuel plant. In future it may be energy storage. Energy storage is far more expensive than fossil fuel plant. Currently, pumped hydro is the cheapest energy store but the cost of that is huge. For a wind-powered Britain. (a, b)
  2. It's less efficient. The extra fossil plant required to backup wind and solar runs less efficiently. 1st: it cycles on/off more (wasting more energy to get hot). 2nd: It is often left on to keep boilers hot, without generating any electricity at all. If energy storage is used instead, inefficiencies are introduced because energy is lost when storing and lost again when using (converting from PE to electricity). Also, the majority of energy store technologies lose energy whilst actually storing. The longer energy is stored the more is lost. ( c )
  3. Significant CO2 emissions continue. Anticipated CO2 reductions from renewable energy have not arrived. Germany is the most spectacular example of this failure. It's mainly because fossil plant now runs more inefficiently. (f, g, h)

The myth of "Wind is always blowing somewhere". One RE plan builds interconnectors between countries so that on a windless day, Britain, for example, will be supplied by windy Germany or sunny Spain. The problem with this notion is that it will rarely work. Low wind periods are often seen throughout the whole of Europe! Nor will sunny Spain be much use to Britain in winter. (d, e)


  1. I calculate Britain would need 17,464 GWh of pumped hydro to buffer wind
  2. Pumped storage will increase costs 10 fold (youtube)
  3. Hidden CO2 emissions from renewables
  4. Wind Blowing Nowhere
  5. Wind Blowing Nowhere – Again
  6. No German CO2 emission reductions for 6 straight years
  7. Grand Debacle: Germany’s Renewable Energy Effort Turning Into A Colossal, Costly And Senseless Failure!
  8. Germany’s 2020 greenhouse gas target is no longer feasible

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