Why renewables are not the answer to energy security
- Published on Thursday, 15 December 2011 13:02
- Written by Martin Livermore
The government’s vision of a clean, green future includes a target of 15% of energy consumption from renewables by 2020. They plan to achieve this primarily via a massive investment in wind turbines. Solar panels, as well as being very expensive, are very inefficient in northern Europe, and burning biomass can make only a relatively minor contribution and is best exploited in small local projects rather than co-firing conventional plant such as Drax. Wind is the only technology which can be deployed at a large enough scale
It is a seductive prospect: instead of burning expensive and finite reserves of gas and coal we could harvest the vast amount of ‘free’ energy in the form of wind. But, like so many seemingly good ideas, reality is rather different. Wind and water power were in common use for milling wheat and a range of other purposes until a better technology came along and they were replaced by steam power in the Industrial Revolution.
Today’s wind turbines look very different from the windmills of the Middle Ages, but they still suffer from the same critical drawback: they provide only an intermittent and unreliable source of energy. Across the UK, wind farms produce only about 25% of their rated output over a year; off-shore rather more so, on-shore often less. So a headline which tells us that a new wind farm can provide electricity for 10,000 houses should really say that it can do this only at certain times, and not necessarily when demand is high.
A particular problem is that very cold winter weather – when energy demand is at its highest – not infrequently coincides with stationary, large-scale high pressure areas under which the air is very calm and very little wind power can be generated. And anyone in Scotland or the north of England last week will have experienced the opposite problem: wind turbines had to be shut down because the wind was blowing too strongly.
It is argued that such problems could be solved by creating a Europe-wide electricity grid, so that power generated in a region where it is windy can be despatched to where there is demand. But such a grid is still simply an idea, which could only be completed after spending many tens of billions of euros over a long timescale. And, even if completed, recent research shows that wind patterns across Europe are often quite synchronous; if it’s calm in one part, wind speeds are also likely to be low elsewhere.
The example of Denmark is an interesting one. For long one of the leaders in wind power, the country currently generates around 20% of its electricity from wind farms. However, if we look at consumption figures, only about 10% of electricity actually used by Danes comes from wind. The rest is generated when it is not needed and has to be sold at low spot prices to neighbouring Norway, Sweden and Germany. At other times, more expensive electricity must be imported.
Despite the rhetoric and the good intentions, pushing ahead with more wind farms will do nothing for energy security without additional gas-fired backup capacity, and emissions reductions are also therefore quite modest. The current policy means that consumers are paying higher bills for no benefit.