Renewables and Storage Could Power Grid 99.9% of Time

By CnAgri Print

Renewable energy could fully power a large electric grid 99.9 percent of the time by 2030 at costs comparable to today抯 electricity expenses, according to new research by the University of Delaware and Delaware Technical Community College.

A well-designed combination of wind power, solar power and storage in batteries and fuel cells would nearly always exceed electricity demands while keeping costs low, the scientists found.

"These results break the conventional wisdom that renewable energy is too unreliable and expensive," said co-author Willett Kempton, professor in the School of Marine Science and Policy in UD'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."

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 United States' 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.

The study used estimates of technology costs in 2030 without government subsidies, comparing them to costs of fossil fuel generation in wide use today. The cost of fossil fuels includes both the fuel cost itself and the documented external costs such as human health effects caused by power plant air pollution. The projected capital costs for wind and solar in 2030 are about half of today抯 wind and solar costs, whereas maintenance costs are projected to be approximately the same.

The research was published online last month in the Journal of Power Sources.