ABSTRACT
The growing market penetration of variable renewable generators, such as wind, is causing existing generators to cycle in order to compensate for wind's variability. For large generators, cycling means operating in a less efficient way, leading to higher fuel costs and air emissions. In a power system using natural gas generators to compensate for wind or solar power's variability, found that air emissions benefits were somewhat less than those expected based on an average emissions factor calculation. When 20 natural gas plants, with the required number of plants operating as spinning reserve, were used to balance 20" renewables, we found that 87 to 93" of the expected reduction in CO2 emissions was achieved. It could be argued that the results for the hourly model are biased by our inattention to changes in subhourly ramping of gas turbines. In addition, one or more of the fossil plants used to compensate for wind.
