It only has symbolic significance, but at half past nine this morning wind was supplying more electricity to the national grid than nuclear.(1) For a few minutes, the gusts over the western side of the United Kingdom supplied more than 6 gigawatts and a temporary slight dip in nuclear output meant that wind was more important for electricity supply than the UK's ageing nuclear fleet. The new record came a few hours after news stories about new cracks in the graphite blocks of one of the reactor at EdF's Hunsterston plant. We'll see more and more days when wind power beats the geriatric nuclear fleet. A couple of other features of electricity supply over the past 24 hours are worth mention. At 4am this morning, the price of power (as indicated by the sell price in the 'balancing market' that keeps electricity supply and demand in balance) fell to a low of just over £1 per megawatt hour. They were basically giving the stuff away. Even at this time of the morning electricity generally sells for thirty times this amount. The high volumes of wind-generated electricity caused substantial disruption to the working of the power market for a few hours.

At almost the same time, we saw the interconnector between France and England change the direction of flow. Normally France pumps almost two gigawatts into the UK. For a few hours the UK exported power instead and the interconnector took 2 gigawatts to France. It's difficult for outsiders to be sure of this but the National Grid appeared to also curtail (shut down) a large fraction of UK wind supply.

These related events matter more than the symbolic event that happened at half past nine. They show just how challenging the future of electricity supply is going to be and how urgently action is needed. Yes, the France interconnector took the temporary surplus off to the European grid early this morning for an hour or so. But the operators of the Grid needed to use almost the full capacity of the interconnector. As wind power grows, Atlantic storms risk becoming much more difficult to manage.

We need more interconnectors, more storage and, please, a way of converting surplus electricity into other usable fuels such as gas. Otherwise all that wind power investment is going to be largely wasted in the winter months.

(This article was published on The Guardian web site on Monday 6th October)

(1) Before counting the power from smaller wind farms attached to the networks of district operators)