Sunday, June 23, 2019
Envisioning A Power Resilient Ukiah
written 16 June 2019
published 23 June 2019
The recent plan by PG&E to shut down the grid to prevent wildfires demands considering what a power resilient community would look like.
Calistoga experienced several weeks of lost power during the Tubbs fire in 2017. Even though it never burned into the town, businesses lost revenue, schools were closed, residents lost perishables, and there was great uncertainty about duration of the shutdown. In response, the city has funded a study to design a stand-alone micro grid, using solar and geothermal sources, combined with battery storage, allowing critical parts of the city to function even when the grid is down.
Montecito has come to the same micro grid conclusion resulting from their experience with the Thomas fire the same year. They are exploring a system where phase one would power the Fire and Water department headquarters, key wells and pumps, and emergency centers and supply facilities, defined as the local school, a small market, a gas station, a bank, and the post office. Phase two would expand the system to include a large grocery store and pharmacy, the sanitation district and several restaurants.
Unlike Calistoga, Ukiah has no local geothermal source, but there are two small generators (1 MW & 2.5 MW) at the Lake Mendocino dam, which could become the foundation for an emergency micro grid for the City. At best, this would cover a portion of the 300 MWhrs consumed on an average day, depending of water levels behind the dam. But in an emergency, a little power is much better than none at all. The existing city grid configuration is not designed to power specific facilities in an emergency, but that could be changed.
At a minimum, phase one should include essential city services, such as Fire, Police, and Sheriff headquarters, and especially their respective communication centers. City water and sewer headquarters, and all the wells, pumps, and treatment facilities should be included. The City has yet to clarify what part of the water and sewer system can work with no grid power, or how long their backup generators can function, or if they can power the entire system. Even if these diesel generators are adequate, we will be shifting from a normal of 70% green power to 100% brown power during a grid shutdown, which is not sustainable. A power down could happen during a triple digit heat event, requiring one or more emergency cooling centers, also helping people with medical needs that require power.
This bare minimum might be provided with a city grid redesign, powered by local hydro power, existing backup generators, and some added battery storage in key locations. But PG&E reports there could be as many as 20 shutdowns a season, some lasting for several days. The disruption to the community, and the economic losses incurred, will be significant. Unfortunately, the way the climate is trending, 20 shutdowns a season might become a low estimate. A power resilient community could be designed to thrive despite intermittent power.
Ideally, every home and business would have the capacity to collect and store power as it is available, wired to power critical circuits during a grid emergency.
Grocery stores and gas stations would have rooftop and parking lot solar arrays, with onsite power storage, allowing some functions to continue during a power shutdown. Businesses, particularly restaurants and banks, would also have collectors and storage to allow them to continue to serve the population during an emergency, as would schools and the hospital. Since phone communication is essential for fire preparedness, all cell towers would need to operate during a grid shutdown.
Our current system was built expecting power be available as needed, so we must re-build our systems to respond to this new normal. Electricity is so cheap and plentiful we waste it, but we can survive on much less for short durations. We don't need to create local systems to provide normal daily consumption. Only a fraction will be required, but it will make the difference between economic chaos with life-threatening disruptions, and a viable, resilient community.
This won't happen overnight, and the cost will be significant, but the cost of doing nothing will be even higher, so we need to start now.