Renewable sources such as solar and wind have variable output. Would an RES affect the reliability of the energy system?
The electric system is designed to handle unexpected swings in energy supply and demand, such as significant changes in consumer demand or even the failure of a large power plant or transmission line. There are several areas in Europe, including Spain, Germany, and Denmark, where wind power already supplies over 20 percent of the electricity with no adverse effects on the reliability of the system. Several important renewable energy sources, such as geothermal, bioenergy, and landfill gas systems can operate around the clock. Studies by the EIA8 and the Union of Concerned Scientists9 show these renewable energy facilities would generate over half of the nation’s non-hydro renewable energy under a 20 percent RES in 2020. Renewable energy can increase the reliability of the overall system, by diversifying our resource base and using supplies that are not vulnerable to periodic shortages or other supply interruptions. Solar energy is also generally most plentiful when it is most needed—in
