Spain has become the world's third-largest generator of wind power, and the second-largest of solar, in a bid to cut greenhouse gas emissions and dependence on imported oil and gas.
But output from Spain's wind parks has on occasion dropped from 11,000 MW to 200 MW within a 12-hour period, and the country can import no more than 3% of its power needs, so combined-cycle gas turbines (CCGTs) need to fill the gap.
Antonio Gonzalez, 'delegate north' for national power grid operator REE told the European Autumn Gas Conference in Bilbao that REE had prepared gas plants to make up potential deficits.
"It is difficult for a country without significant international connections to maintain renewable energy [output] in a safe way," he added.
Alongside wind power, CCGTs have also boomed in Spain, from none in 1996 to 55 at present, which can produce up to 22,000 megawatts of power.
Gas plants quick to start
Juan Pons, managing director of strategy at gas grid operator Enagas, said CCGTs can be up and running from a cold start in three to six hours, much more quickly than coal or nuclear power stations.
However, Spain lacks the cross-border pipelines needed to import the sudden surge in gas needed to start up CCGTs when wind power drops.
"So you need something that can provide an enormous flow of gas in two to three hours, and this is possible in Spain due to LNG [liquified natural gas] facilities," Pons said. "I think renewables and gas are condemned to be friends."
Spain is the world's third-biggest importer of LNG, after Japan and South Korea, and has six regasification plants.
In order to achieve European Union targets to derive 20% of all energy from renewables in 2020, the Spanish government estimates that wind parks will need to grow to 29,000 MW of capacity by 2016, from 17,000 at present.
To complement that expansion, the government predicts Spain will need to boost the total capacity of its gas-fired generators to 33,000 MW from a current 22,000 MW.
Pons thought that utilities were unlikely in the near term to build more CCGTs after completing seven or eight currently under construction, but that Spain would have enough storage capacity for gas in its LNG terminals.
Enagas estimates that Spain's CCGTs were only running at 52% of capacity in September.
Joaquin Garcia, director of promotion at EDP Renewables, whose Portuguese parent company operates CCGTs, said regulation could encourage the building of more gas plants.
"We need government to send the right signals," he said. "We support all the renewable energy we need with CCGTs as back-up. At night, if you have no sun or wind, you need something available for use."
(EurActiv with Reuters.)