The wind energy industry has seen a lot of growth over the past decade, and has become a dominant force in the renewable energy industry, up against traditional heavyweights like solar. Public support for wind is growing with each year, and leading wind companies like Vestas are developing more efficient and taller turbines.
Now, a new study by Stanford University researchers has shown that wind energy can create three days of uninterrupted power for storage on top of what is immediately consumed, enough to get through even the worst lull in weather.
“Whenever you build a new technology, you have to invest a large amount of energy up front,” said Michael Dale, a research associate at Stanford, referring to the development and manufacturing costs of any new technology.”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?”
In a report for the journal Energy & Environmental Science, Dale and his colleagues from Stanford detail their research which has shown that the wind industry can provide more than three days of uninterrupted power.
“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.
The Stanford team considered a variety of storage technologies to work in conjunction with wind energy, including batteries and geologic systems such as pumped hydroelectric storage.
“Wind technologies generate far more energy than they consume,” Dale said. “Our study showed that wind actually produces enough surplus electricity to support up to 72 hours of either battery or geologic storage. This suggests that the industry could deploy enough storage to cope with three-day lulls in wind, common to many weather systems, and still provide net electricity to society.”
Surprisingly, at least from this author’s perspective, onshore wind farms were the favourites in this scenario, over offshore wind:
“We found that onshore wind backed by three days of geologic storage can support annual growth rates of 100 percent – in other words, double in size each year – and still maintain an energy surplus.”
“These results are very encouraging,” said study co-author Sally Benson, a professor of energy resources engineering and director of the Global Climate and Energy Project (GCEP) at Stanford. “They show that you could create a sustainable energy system that grows and maintains itself by combining wind and storage together. This depends on the growth rate of the industry, because the faster you grow, the more energy you need to build new turbines and batteries.”
Sadly, the same could not be said for the solar industry, which was also evaluated in the report. According to the Stanford researchers, the solar industry can only afford approximately 24 hours of energy storage, “because it takes more energy to manufacture solar panels than wind turbines.” According to Dale, “the solar industry can also achieve sustainable storage capacity” but only “by reducing the amount of energy that goes into making solar photovoltaics.”
“Our analysis showed that, from an energetic perspective, most photovoltaic technologies can only afford up to 24 hours of storage with an equal mix of battery and pumped hydropower,” Dale said. “This suggests that solar photovoltaic systems could be deployed with enough storage to supply electricity at night, and the industry could still operate at a net energy surplus.”
Benson added that one of the biggest differences between solar and wind is the return on investment: “Within a few months, a wind turbine generates enough electricity to pay back all of the energy it took to build it,” she said. “But some photovoltaics have an energy payback time of almost two years. To sustainably support grid-scale storage will require continued reductions in the amount of fossil fuel used to manufacture photovoltaic cells.”