Wind farms can provide a surplus of reliable clean energy to society, Stanford study finds

oday's wind industry, even with the necessary batteries and other grid-scale storage, is energetically sustainable, Stanford scientists say.

BY MARK SHWARTZ

Dennis Schroeder/NREL

A big challenge for utilities is finding new ways to store surplus wind energy and deliver it on demand. It takes lots of energy to build wind turbines and batteries for the electric grid. But Stanford scientists have found that the global wind industry produces enough electricity to easily afford the energetic cost of building grid-scale storage.

The worldwide demand for solar and wind power continues to skyrocket. Since 2009, global solar photovoltaic installations have increased about 40 percent a year on average, and the installed capacity of wind turbines has doubled.

The dramatic growth of the wind and solar industries has led utilities to begin testing large-scale technologies capable of storing surplus clean electricity and delivering it on demand when sunlight and wind are in short supply.

Now a team of Stanford researchers has looked at the "energetic cost" of manufacturing batteries and other storage technologies for the electrical grid. At issue is whether renewable energy supplies, such as wind power and solar photovoltaics, produce enough energy to fuel both their own growth and the growth of the necessary energy storage industry.

"Whenever you build a new technology, you have to invest a large amount of energy up front," saidMichael Dale, a research associate at Stanford. "Studies show that wind turbines and solar photovoltaic installations now produce more energy than they consume. The question is, how much additional grid-scale storage can the wind and solar industries afford and still remain net energy providers to the electrical grid?"

Writing in the March 19 online edition of the journal Energy & Environmental Science, Dale and his Stanford colleagues found that, from an energetic perspective, the wind industry can easily afford lots of storage, enough to provide more than three days of uninterrupted power. However, the study also revealed that the solar industry can afford only about 24 hours of energy storage. That’s because it takes more energy to manufacture solar panels than wind turbines.

"We looked at the additional burden that would be placed on the solar and wind industries by concurrently building out batteries and other storage technologies," said Dale, the lead author of the study. "Our analysis shows that today’s wind industry, even with a large amount of grid-scale storage, is energetically sustainable. We found that the solar industry can also achieve sustainable storage capacity by reducing the amount of energy that goes into making solar photovoltaics."

Reducing energy inputs to battery manufacturing is also needed, he said.