Improved resilience has emerged as a top priority for the U.S. power grid. Efforts to mitigate wildfire risk in Northern California last year led to hundreds of thousands of electricity customers being disconnected from the grid. During hurricane season, customers in the Eastern and Southern U.S. often face the associated threat of multi-day power outages. In many other parts of the country, portions of the local power grid are susceptible to interruptions due to a variety of other factors. Improved resilience would reduce or avoid those outages, allowing industries, businesses, and households to maintain their uninterrupted supply of electricity.
Resilience can be improved through the deployment of microgrids, among other options such as vegetation management and circuit hardening. Microgrids have been described in a wide variety of ways. Simply put, the term “grid” refers to a combination of power generation, customers who consume the power, wires that deliver the electricity to customers, and a control system that manages this process. As discussed in this paper, a microgrid simply is a small, self-sufficient grid.
Some types of microgrids provide resilience by serving load locally. If portions of the power grid are temporarily turned off to prevent wildfires or if a transmission line is taken offline during a hurricane, microgrids “downstream” of those interruptions continue to keep the lights on by providing power from local resources.
Parallel to the search for improving grid resilience is a strong focus among utilities and policymakers on a cleaner U.S. power supply, with goals to limit greenhouse gas (GHG) emissions and improve local air quality. Twenty-one utilities and 23 states have committed to massive reductions in electricity generation emissions – typically reductions of 80% or more – over the next 10 to 30 years.