The Problem With Wind

What happens when it isn’t windy?

UK Windfarm Fleet Load Factors 2003 - 2010
The biggest single criticism  of  wind power as a large scale generator is that it isn’t there when the wind stops blowing. Even on a year by year basis output from installed wind capacity in the UK is far from even (see diagram on right),  and it is not unusual for the whole of the country to be covered by a big high pressure system in Winter, with still air and very low temperatures. The argument put forward by the wind companies is that the distribution of windfarms throughout the UK ensures that power generation is evened out, and they have further suggested that a European ‘supergrid’ (not yet built) would further ensure continuation of supply.  I have to say that  recent experience suggests otherwise.

At 17.30 on the 7th of December 2010, when the UK grid  recorded its fourth highest load of 60,050 MW  the UK wind fleet, with c. 5,200 MW headline capacity, was producing about 300 MW, a Load Factor of just 5.8%. One of the largest wind farms in the United Kingdom, the 322 MW Whitelee Wind Farm was producing approximately 5 MW, a Load Factor of 1.6%.  Meanwhile, load factor in other European countries at exactly this time was also low. The German wind fleet was recording a load factor of approximately 3% (830MW/25,777 MW) and Denmark 4% (142 MW / 3,500 MW).

Such figures tend to confirm theoretical arguments that regardless of the size of the wind fleet the United Kingdom may never be able to reduce its conventional generation fleet much below peak load requirements without running the risk of interruption.

Possible Solutions

Proposed European 'Supergrid'

Scottish and Southern Energy, Vattenfall and Norwegian utilities Adger Energi, E-Co Energi and Lyse have signed a cooperation agreement to build an interconnector between Scotland and Norway. They will establish NorthConnect, a jointly owned interconnector development company. The connection will have a capacity between 1.2 and 2GW, and is planned to be in operation by 2020.

(We should also remember that before this Scotland still needs to install high capacity lines  to bring the electricity form the Western and Northern seas and islands to the existing grid).

More nebulous and further away is the proposal for an offshore supergrid linking projects in the North, Baltic and Irish Seas, first put forward at the UK-Baltic-Nordic Summit in London.  The North Seas Offshore Grid initiative should allow energy ministers to work together to try to create the right framework for industry to invest in future projects. It includes the UK, Ireland, Sweden, Denmark, Germany, the Netherlands, Luxembourg, France, Norway and Belgium.

Another way to deal with variable supply that has been put forward is the ubiquitous installation of ‘smart meters’. These would, it is suggested, automatically vary the price per unit for various appliances and devices in the home, allowing  consumers to make informed decisions as to how much energy they use, where and when. This way it is suggested that the market could regulate demand to cope with variability. The main  problem with this is that smart meters of this sort don’t exist yet and the timescale for deployment would almost certainly lag behind the planned installation of wind capacity. Additionally, no-one is ion a position to predict how much variability of supply this mechanism could cope with.

The Real Answer

The real answer is to find a way of storing surplus wind energy in a form that can be used later.  Storing up to four times Scotland’s current consumption in batteries is never likely to be an option, no matter how much battery technology progresses. Of course we already have one very elegant solution in the form of the pumped storage hydro schemes at Cruachan and Foyers, but sites for new schemes are limited and tend to run into opposition form environmental groups. (More on this in a future article).

The most promising solution would seem to be using the vast wind surplus that Scotland is planning to install to make hydrogen. This process uses huge amounts of electricity but only requires water as a raw material. This would create a storable fuel that could be burned to generate electricity or – more probably – used to run surface vehicles. The favourite option at the moment for hydrogen powered vehicles  is fuel cell technology,  but it is also possible for  cars could not burn hydrogen directly  in an internal combustion engine  instead of petrol or diesel. In either case, the safe storage and distribution of highly compressed hydrogen is the main technical obstacle. We will look at hydrogen more closely in the next article.

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