"Once again, the sector has debunked myths, long since discredited yet still propagated by certain areas of the national and international press, that wind cannot produce significant amounts of electricity without destabilising the electricity system," says Sergio de Otto, communications director at national wind association Asociacion Empresarial Eolica (AEE).
"We've made huge efforts to integrate wind into the system and that work's paying off," adds the association's technical director, Alberto Cena.
Strong winds on November 8 supplied over half of the electricity consumed in Spain between 3 am and 8.30 am, according to system operator Red Electrica de Espana (REE). During that time, electricity demand ranged between 19.7 and 21.7 GW. At one point, 10.2 GW of wind power flowed onto the system, supplying 53.7% of demand and breaking the previous record of 45% achieved three days earlier. The system was partly balanced by exporting power across the border into France and into hydro pump storage.
Throughout the day until 6.30 pm, wind supplied at least 45% of demand. At one point during the evening, wind produced more than 11.6 GW, surpassing the previous record of 11.2 GW on March 5. Its lowest point came in the evening, at 37%.
REE, once outspoken in its criticism of wind power, now has only words of praise. The records present "a milestone for the electricity system of which we feel particularly proud", says REE President Luis Atienza. "We are very satisfied to be world leaders in renewables grid integration."
Six years ago, REE warned that wind could supply no more than 12% of Spain's total electricity demand at any given time, for fear that it would overwhelm the grid operator's ability to respond. Spain's electricity transmission links to the rest of Europe, which go through France, total 3 GW - too little, said REE at the time, to allow it to effectively compensate for unexpected changes in wind production.
The wind sector has since come a long way, thanks largely to government regulations introduced at REE's behest.
Coping with excess
From January 2008, all wind production has been monitored in real time, granting the system operator emergency control of wind farms anywhere in the country during unanticipated imbalances in supply and demand or grid malfunction. This means if supply overflow is forecast, NEE has more leeway to balance the system.
There have been growing pains despite improvements from centralised monitoring. One November morning in 2008, unexpectedly strong winds resulted in large volumes of wind being thrown off the grid. Miguel de la Torre, a supervisor at REE's electricity control centre, says a combination of factors required the curtailment of 1.4 GW of wind power. Because of problems with communications technology and methodology, the operator in fact curtailed nearly double that.
REE says the problems have since been resolved (Windpower Monthly, May 2009). Wind power has met more than 40% of demand on several occasions without any curtailment - an achievement that De la Torre attributes to more stable wind and better scheduling of wind power supply.
Even so, to improve Spain's ability to react to unpredicted strong wind, AEE and REE are pushing to speed up expansion of interconnection with France's grid and to build new hydro pumped storage. In that technology, surplus electricity power turbines push large volumes of water uphill, and the water is later released to flow back downhill through the same turbines, to generate electricity.
Spain currently runs 5.5 GW of hydro pumped storage. A further 2 GW of new capacity could accommodate all excess wind production to 2016, says REE's system operations director, Miguel Duvison.