The electric grid system in the United States is changing slowly but surely to improve service and reliability as well as reduce carbon emissions. As such, policymakers, independently owned utilities, customers, and other stakeholders are working to adjust how the nation generates, transmits, and consumes electricity.
Perhaps the most dramatic changes have occurred in production as the share of electricity generated by renewable resources has grown tremendously in recent years. According to the Energy Information Administration (EIA), renewables (wind, solar, and hydropower) accounted for 17.5 percent of electricity generation in 2019, up from about 10 percent in 2010. The share of electricity produced by fossil fuels was 63 percent in 2019, down from 69 percent in 2010.
Part of what has made the growth in renewables possible is the ramp rate of natural gas. The ramp rate is the speed at which an electricity generator can increase (ramp-up) or decrease (ramp down) generation. Coal and nuclear plants have prolonged ramp rates, while oil and natural gas facilities ramp much more quickly. Solar and wind ramp rates are highly variable and can take a few minutes up to several hours. Because of the variable ramp rate of renewables and the slow ramp rate of coal and nuclear power, natural gas has served as the intermediate choice of utilities over the past decade.
In the future, the role of natural gas as an intermediate is expected to decline, however. Growth in demand response mechanisms among utilities will account for at least part of that decline. Demand response mechanisms work to reduce demand for electricity at the consumer level. Taxes and fees for peak energy usage, as well as automated controls, are both examples of demand response.
Experts expect the rest of the decline to come from expanded and improved energy storage. Stored energy at various points in the grid will help off-set the variability of renewables by providing power when generation is low or in the process of ramping up.
While a seemingly minor logistical issue in the electric grid system, ramp rates have actually played a critical role in determining the United States’ energy mix. As technology improves, however, one should expect the impact of ramp rates, and the role of natural gas an intermediate, to diminish. This would most likely lead to a decrease in the amount of natural gas used for electricity generation in the future.