Renewable energy can power electric grid
Renewable energy from wind and solar power could support a large electric grid 99.9 percent of the time by 2030, at current costs, new research says.
"These results break the conventional wisdom that renewable energy is too unreliable and expensive," said study co-author Willett Kempton, professor of marine science at University of Delaware's College of Earth, Ocean, and Environment.
"The key is to get the right combination of electricity sources and storage - which we did by an exhaustive search - and to calculate costs correctly," added Kempton, according to an university statement.
The authors developed a computer model to consider 28 billion combinations of renewable energy sources and storage mechanisms, each tested over four years of historical hourly weather data and electricity demands.
The model incorporated data from within a large regional grid called PJM Interconnection, which includes 13 states from New Jersey to Illinois and represents one-fifth of the US total electric grid.
Unlike other studies, the model focused on minimizing costs instead of the traditional approach of matching generation to electricity use.
The researchers found that generating more electricity than needed during average hours - in order to meet needs on high-demand but low-wind power hours - would be cheaper than storing excess power for later high demand.
Storage is relatively costly because the storage medium, batteries or hydrogen tanks, must be larger for each additional hour stored.
One of several new findings is that a very large electric system can be run almost entirely on renewable energy.
"For example, using hydrogen for storage, we can run an electric system that today would meeting a need of 72 GW, 99.9 percent of the time, using 17 GW of solar, 68 GW of offshore wind, and 115 GW of inland wind," said co-author Cory Budischak, instructor in the Energy Management Department at Delaware Technical Community College and former Delaware student.
A GW (gigawatt) is a measure of generation capability. One GW is the capacity of 200 large wind turbines or of 250,000 rooftop solar systems.
Renewable electricity generators must have higher GW capacity than traditional generators, since wind and solar do not generate at maximum all the time.