By Jason Deign in Barcelona

If Mauro Villanueva Monzón has his way then the answer to one of wind energy’s most intractable problems could one day be in your garage.

The Gamesa technology development director is leading a research project into the viability of using electric car batteries as storage devices for excess wind energy.

Dubbed Cars4Grid, the project is the most ambitious of three Gamesa is carrying out to reduce the intermittency of supply to the electrical grid, an issue that has long been seen as the Achilles heel of renewable energy in general and wind power in particular.

However, says Villanueva, the fact that the wind does not blow every day should not be seen as a challenge for renewable energy but rather a challenge for the power distribution model we are used to. It does not rain every day, either; but that has not been a problem for water distribution.

“The first thing to bear in mind is that the electrical system in general has been in a privileged position thanks to fossil fuels,” he says. “Fossil fuels are a gift that we have been relying on for a long time but they are not sustainable.

“As long as our electrical system has been supported by stored-energy sources such as petrol, gasoline or uranium, it hasn’t needed a storage system like water does.

Variable supply

“The need to accommodate a variable supply is not a need that comes from wind power or from renewable energy but from the evolution towards a more modern system of distribution.”

This more modern system of distribution will likely be the smart grid, a regional or even continental electricity network able to control and route power much more intelligently than is currently the case, making better use of available energy sources to maintain constant supply.

Much of the success of future smart grids will depend on their ability to tap into distributed power sources such as the car batteries envisaged in the Cars4Grid scheme. In the meantime, Gamesa is focusing on other types of battery development for its other power storage projects.

One is a short-term plan to develop electro-chemical batteries based on current technology that will sit alongside individual turbines and provide an immediate storage capability. Villanueva says these should be available commercially in the next three years.

The final Gamesa storage project, which Villanueva says is still very much in the initial research and “high risk” phase, is to develop high-capacity flux batteries capable of storing tens of megawatts an hour.

These could be used to store excess power from wind farms or over-saturated electricity grid nodes. As reported in Wind Energy Update, Xcel Energy in the United States has already developed a wind-to-battery system that can store 7.2 megawatt hours of electricity.

Tweaking output

Batteries are not the only answer to intermittency, however, and may not even be the best.

Carlos Lozano, head of research and development at Iberdrola’s renewable energy division, is looking to even out total wind energy delivery by tweaking output rates at the turbine, farm, farm cluster and regional levels.

The idea is to maintain output levels somewhat below the optimum for average conditions, so that if the wind drops turbine throttles can be relaxed and additional turbines, farms or farm clusters can be started up to maintain a constant supply to the grid.

Doing this will require turbines and grid systems to be more flexible and responsive than at present, and Iberdrola is working with Gamesa and Spanish power grid operator Red Eléctrica de España on the changes needed.

But the highest-profile result of the work to date is the €8.15 million Syserwind project.

This is the first of the six so-called Twenties initiatives receiving a total of €58 million from the European Union in order to show how significant amounts of wind energy could be incorporated into the grid without destabilising it. 

Unfavourable weather

Syserwind will involve operating 480MW of Gamesa turbine wind farms in Granada, Málaga and Cadiz at below-optimum levels, allowing Iberdrola to ‘switch on’ additional capacity as needed to maintain a near-constant energy supply even in unfavourable weather conditions.

Eduard Sala de Vedruna, research director of Europe Wind Energy Advisory at IHS Emerging Energy Research, says Syserwind makes sense for a large wind farm operator such as Iberdrola.

“Even wind farms with a low performance can be worthwhile because they can help stabilize the supply,” he says. “It’s basically asset management.”

Syserwind could start yielding results this year and in the meantime the best bet for wind energy to establish itself as a base load is to use excess electricity to pump water into dams that can then power hydroelectric plants.

“Right now, in terms of storage the only proven option is pumping,” says Iberdrola’s Lozano. “Other technologies are not yet viable in terms of power or cost.”

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