Scotland’s renewable energy future is a mirage, says one organisation
In December, the Scientific Alliance and Adam Smith Institute produced a report on the contribution of renewables to Scotland’s future energy mix. With the First Minister talking of the country becoming the ‘Saudi Arabia of renewable energy’ and both Holyrood and Westminster seemingly convinced that injecting taxpayers’ money into the sector is both necessary and desirable, we thought it was time to take a step back and look at the facts rather than the political assertions.

Scotland, of course, is not just windy but has a long Atlantic coastline with, superficially, plenty of wave and tidal power available for exploitation.

In the report, therefore, we looked at the potential of all available and emerging renewable energy technologies: wind, wave, tidal, hydro, solar, biomass and heat pumps.

Of these, solar is not suited to the needs of a country in such northerly latitudes; even in England and Germany, it is both expensive and inefficient.

Biomass has some potential, particularly for small-scale, localised projects, but neither Scotland nor the UK as a whole could supply more than a small fraction of energy needs without imports.

Wave and tidal power, despite their apparent attractions, still have a long way to go before they might be commercially available. Hydroelectricity is a well-proven and efficient technology, but has little or no potential for expansion in this country.

This leaves wind as the only technology capable of being deployed on a large scale; in practical terms, ‘wind energy’ and ‘renewable energy’ will be interchangeable terms for the foreseeable future.

It is undeniable that there is an enormous amount of ‘free’ energy in moving air and water and being able to harvest that is a seductive prospect. The problem is that it is very diffuse. Coal and gas are very concentrated sources of energy, and uranium even more so. This is what makes them so useful for power generation. The situation with wind is quite different; rather than bring gas to a compact power station near where electricity is needed, large numbers of individual turbines have to be erected where the wind blows strongly, and the power transmitted over long distances to where it is consumed. The row over the new Beauly-Denny power line is simply a taste of things to come.

Since the wind does not blow consistently, wind farms do not produce electricity all the time.

The percentage of rated output which is actually generated over a year is called the capacity factor.

Across the UK, this is currently about 25 per cent, which means that, in general, four times the rated capacity must be installed to give the required output averaged over the year. When we hear statements such as ‘this new wind farm can supply enough electricity for 10,000 homes’, a more accurate translation would be ‘this new wind farm will on average power 2,500 homes but sometimes it could be up to 10,000 and other times it could be none’. Unsurprisingly, ministers and power companies rarely choose to express themselves with this degree of accuracy.

But enthusiasts would say, quite rightly, that no one is suggesting that wind power can supply 100 per cent of our needs. They point out that the operators of the electricity grid are used to balancing supply and demand and are quite able to deal with variable output from wind turbines. Up to a point, this is also right, but because a system is capable of accommodating a few per cent of very variable input, this does not mean that the situation would be as simple as more and more wind farms come on stream.

Intermittency is the Achilles heel of any renewable energy technology, with the exception of burning biomass (and, over limited timescales, hydro power). Tidal power at least has the advantage of predictability, but wind is variable from minute to minute, hour to hour and day to day. Forecasters can normally say whether the next few days are likely to be windy or not, but only within a range of uncertainty about average speed.

Wind speed is even more important than you might think because, in technical terms, the amount of power generated follows a cube law. This means that, for example, if the wind speed increases from 10-20mph, the power output goes up eight-fold rather than doubles! In typically variable or even gusty winds, electricity generation varies very significantly over short timescales.

Over longer timescales, there may be significant periods when little or no power is generated. Not infrequently, Europe has extended periods of high pressure which remain stationary over wide areas. In winter, these lead to very cold, bright and calm conditions. The low temperatures mean that power demand is at a peak, but wind turbines are producing little if any power.

But, as this winter’s weather has demonstrated very clearly, too much wind is as bad as too little.

Once wind speeds get much above 50mph, turbines begin to shut down automatically to reduce the risk of damage. All parts of the structure are subject to large, fluctuating stresses and there have been cases of blades breaking and even the whole structure blowing down. In December, many newspapers published photographs of a turbine assembly bursting into flames when the automatic shutdown failed to work properly during the gales.

The consequence of this is that wind farms need conventional generation capacity available to provide backup unless we are prepared to tolerate not infrequent blackouts. With relatively low amounts of wind-generating capacity, existing power stations can probably cope, but as the penetration of renewables increases, then so does the need for additional fossil-fuel stations. While efficient nuclear and modern gas- or coal-fired stations can provide the base load for consumers and industry, these can only be cycled up and down to a limited extent, which means that power generators have to fall back on less efficient open-cycle gas turbines (effectively, stationary aircraft engines) which are very flexible but also produce a lot of un-recovered heat.

This backup capacity has to be held in reserve, on standby, until it is needed at short notice. The cost of generation is therefore relatively high. As more wind farms are built, so more backup capacity is needed, but the cost of this is not added to that of the wind farm. We would argue that the only rational way to assess the economics is to look at the total cost of the generating system as more wind capacity is added. Increasing amounts of wind-generating capacity raise overall costs, but the conventional analysis makes wind power itself look less expensive than it truly is.

Experience from other countries is a good guide to what we might expect if the Scottish Government tries to fulfil its vision of a country producing the equivalent of its own electricity needs from renewables. Geography and climate mean that a significant proportion of this is actually from existing efficient and reliable hydro power, but all new capacity will be in the form of wind farms. Denmark, for example, produces about 20 per cent of its total electricity from wind. However, much of this is generated when it is not needed, with the result that only about 10 per cent of electricity consumed is from wind.

When demand is high and wind output low, the system is balanced by importing nuclear, coal or hydro power from Sweden, Germany or Norway, at relatively high prices (Denmark is fortunate in being a small country with a large amount of interconnection of its power grid with its neighbours). On the other hand, about half the electricity generated from wind farms is exported because it is not needed. Inevitably, since there is surplus, neighbouring countries can buy it at low prices. Scotland might well export large amounts of wind power, but this is likely to be at low prices, while at other times, similar amounts of electricity from conventional stations would be imported at higher prices due to shortterm market forces.

Scottish consumers would effectively be subsidising their neighbours south of the border.

The primary driver of renewables is climate change mitigation policy, which seeks to reduce emissions of carbon dioxide, but adding more renewables to the system does not necessarily cut emissions. In the case of Denmark, imported power may well come from coal- or gas-fired stations. And in the Irish Republic, there is a clear trend for emissions reductions to plateau as more wind power is generated.

The evidence shows that continued investment in wind power will do little to reduce fossil fuel use and will do nothing for energy security. Instead, consumers will pay more both to subsidise wind farm operators and to cover the cost of new transmission lines. If, as seems likely, subsidies are deemed unaffordable in the longer term, the legacy of today’s enthusiasm for wind power will be a countryside scarred by turbine bases and unnecessary power lines, with an economy damaged by the push to create expensive, shortterm jobs in the ‘green’ economy at the expense of more sustainable employment.

Our analysis strongly suggests that the massive investment planned in wind farms would not reduce fossil fuel imports significantly, and cuts in carbon dioxide emissions would come more from replacement of old coal-fired plants by gas turbines than from the contribution of wind itself. Far from Scotland becoming the Saudi Arabia of renewables, its citizens may find that the Government’s vision may prove just to be another mirage.