Commodities: What happens when the wind doesn't blow? 

Chris Huhne, the energy secretary, last week used Scottish Power’s decision to raise electricity bills by 10pc to tout the wisdom of building wind farms instead of fossil fuel plants.

He’s certainly right that “clean energy sources are not vulnerable to global price shocks” in the same way as gas or coal powered stations.

But Mr Huhne neglected to mention that electricity from wind turbines costs twice as much to produce as that from coal or gas stations and will need to be expensively subsidised by green taxes.

The Government may feel this is a fair price for security of supply and cleaner energy. But heavy dependence on wind turbines is going to come with tricky problems for our energy infrastructure that are still far from being sorted out.

Electricity is a unique sort of commodity and can’t easily be stored. This is the main reason why Britain is going to face difficulty balancing its supply and demand when a third of our capacity is provided by wind by 2020.

The government currently wants 30 Gigawatts (GW) out of about 80 GW of generation capacity to be provided by wind. The currently daily demand for power varies between about 50 GW and 60 GW – so what will happen when the wind doesn’t blow?

It would be manageable if turbines ran at a low but constant efficiency. The problem is the swings in windiness, alternating low production with power surges flooding the system with electricity that goes to waste.

Back-up power generation capacity will be available for unwindy days, with gas or coal power filling in the gaps.

What’s difficult to manage is the fact that it takes around three to four hours to switch on a coal station, about 90 minutes to get a gas station running full blast, and several days to crank up a nuclear power station.

The Government’s current favoured solution is demand-side management, which involves controlling the amount of electricity used by consumers. However, some are sceptical about the scale of impact this would have.

What is growing as a possible solution is the idea of building more gas power stations that can be warmed up quickly and shut down immediately. Wartsila, a Finnish company, has one of the leading technologies in this area, building gas plants that can switch on and off in 30 seconds.

“Our plants in America sometimes go on and off ten times a day,” says Vesa Riihimaki, group vice president and head of power plants.

Other companies, such as GE are also developing products in this area.

If the UK is going to hit the current targets on renewable energy set by Europe, it is going to have to replace the vast majority of the stations that are pumping out electricity today.

Most of the coal plants are shutting down and the remaining ones will need to be upgraded with carbon capture technology or partially converted to biomass. Nuclear will be replaced by new stations and oil power plants gradually retired.

It is also beginning to look like many new, super-efficient gas stations are needed to make the system as ready as possible for fluctuations in wind power – and to step in as the UK’s main source of electricity before new nuclear and wind power are constructed.

As Mark Powell, UK head of energy consulting at KPMG, warns, the current price rises based on higher wholesale costs of gas are nothing compared with the costs of green energy.

“Today’s electricity price rises are driven by commodity costs but these will pale into insignificance as the cost of funding decarbonisation starts to hit.

“While new nuclear represents the cheapest form of low carbon energy generation at an estimated cost of £55 to £85 per Megawatt (MW) – compared with £120 to £180 per Megawatt for offshore wind – any post-Fukushima delays could also hike consumers’ electricity bills.

“With ambitious low carbon targets – which include renewable energy generation such as solar, construction of the new nuclear fleet and a new energy infrastructure – needing to be funded, the consumer is invariably going to end up paying one way or another.”