A GW ("gigawatt") is a measure of electricity 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.
The study sheds light on what an electric system might look like with heavy reliance on renewable energy sources. Wind speeds and sun exposure vary with weather and seasons, requiring ways to improve reliability. In this study, reliability was achieved by: expanding the geographic area of renewable generation, using diverse sources, employing storage systems, and for the last few percent of the time, burning fossil fuels as a backup.
During the hours when there was not enough renewable electricity to meet power needs, the model drew from storage and, on the rare hours with neither renewable electricity or stored power, then fossil fuel. When there was more renewable energy generated than needed, the model would first fill storage, use the remaining to replace natural gas for heating homes and businesses and only after those, let the excess go to waste.
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's wind and solar costs, whereas maintenance costs are projected to be approximately the same.
"Aiming for 90 percent or m
|Contact: Andrea Boyle Tippett|
University of Delaware