The researchers ran simulations based on varying levels of battery and electric car storage. Electric cars, which could be tapped during daytime hours to help meet peak demand, provide the cheapest storage option since most of their costs would be absorbed by their owners, Kempton said.
"But with cars, you run into resource constraints," Kempton said. "It's not like every person in PJM is going to have five electric vehicles."
He added, "With wind and solar we don't see the same kind of constraints."
While most analysts believe the world can -- and, if the worst effects of climate change are to be averted, must -- transfer to a predominantly renewable-based energy economy, the role of fossil fuels as backup power supply is still hotly debated.
An article in the Los Angeles Times this week cited several sources as claiming that upscaling renewable would need to be met with a corresponding rise in traditional fossil fuel power plants in order to ensure baseload power supply.
According the University of Delaware study, a large enough system of renewable energy generators could feasibly fill its own reliability gaps. "In our 99.9 percent scenario, we found that, in four years, only five times would you need to bring fossil-fuel plants back online to ensure power supply," Kempton said.
Rather than build new plants, a few of the coal or gas plants offset by new renewable supplies could be kept online to provide that backup power, he said.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500