Scotland’s unevidenced energy claims

The Institution of Mechanical Engineers has called the Scottish Government’s bluff over its renewable energy claims.

In a new report the IMechE criticises the lack of transparency, the overblown claims, and the engineering feasibility of Scottish targets. Some of these issues were ventilated here in June

Unfortunately, the Scottish Government doesn’t show any sign of listening. An unnamed spokesman has responded to the report by re-iterating the same claims, saying that progress towards the target meeting the equivalent of 100 per cent of electricity from renewables is assessed using statistics from the Department of Energy and Climate Change, and that Scottish Renewables estimates that  “in excess of 7 gigawatts of capacity from renewable are already operational, under construction or consented – a level of capacity approaching 60 per cent of Scotland’s gross consumption.”

This statement, whoever drafted it, is innumerate nonsense. It compares installed capacity (or capacity yet to be installed) with consumption. Let’s assume that the 7 GW gets built (a big assumption) and that it runs at full capacity 24 hours a day (a totally impossible assumption). It would then generate, over the course of a year, 61 terawatt hours (TWh) of electricity.

Almost all the electricity would come from wind turbines, which generally operate at no better than 25 per cent of capacity (21.7 per cent in 2010 for wind farms in Scotland). So the best we could hope for if all the promised capacity comes on stream and capacity factors remain unchanged would be 13.3 TWh/y of electricity, less than a third of Scotland’s current electricity consumption.

Bear in mind, too, that wind turbines generate intermittently. That means that back-up capacity fired by coal, gas or nuclear would have to be built or retained for times when the weather was cold but the wind wasn’t blowing. The price for ambitious renewable programmes is that consumers have to pay twice – once for the turbines, and once for the back-up capacity.  Since the Scottish Government wants to move away from nuclear generation, this back-up will eventually require new-build plants burning gas or coal. More realistically, Scotland would import such electricity from England and Northern Ireland.

The Scottish Government has imposed two targets upon itself: that it will generate the equivalent of 100 per cent of its electricity from renewables by 2020; and that by then 30 per cent of total energy consumption will come from renewables.

But, as the IMechE report points out, even if it were possible to achieve the 100 per cent of electricity target, it would barely represent 20 per cent of total energy, not 30 per cent. And to achieve it would involve installing renewable capacity at five times the rate achieved over the past five years, costing billions of pounds and pushing up fuel bills.  So more effort needs to be spent on renewable technologies that provide heat, rather than electricity, IMechE concludes.

Scottish energy policy, as it stands, is a mixture of wishful thinking, boastful talk and engineering ignorance. Nor is it true, as the Scottish Government spokesman said, that “investment in offshore renewable and other clean, green energy sources will also help us to keep energy bills low in the future and therefore combat fuel poverty”. The opposite is more likely to be the case.