San Francisco braces for the Big One with microgrids
In 2008 the U.S. Geological Survey reported that California has a 99 percent chance of a magnitude 6.7 or larger earthquake in the next 30 years.
Just last year, a 6.0 magnitude earthquake knocked out power to more than 40,000 people in the San Francisco Bay area. This was the fourth earthquake of magnitude 6 or greater to hit the Bay Area since 1979, including the 6.9 magnitude earthquake that disrupted the 1989 World Series and knocked out power to 1.4 million people.
So the city of San Francisco is not taking any chances — it's preparing for the (next) big one with microgrids.
"The whole western side of the city is built on sand," said Cal Broomhead, energy and climate program manager for San Francisco’s Department of the Environment (SF Environment). "If we have a massive earthquake, the gas infrastructure will be shot, and we could face an extended power outage."
If the gas pipeline infrastructure is destroyed, it knocks out the natural gas-fired central thermal plants and prevents the use of distributed natural gas generators. The city wanted to find a distributed solution to provide backup emergency power, one that didn't rely on diesel.
In 2015 the city received funding from the U.S. Department of Energy’s Solar Market Pathways Program to integrate solar and energy storage into San Francisco’s emergency response plans. The local utility, Pacific Gas and Electric (PG&E), one of California’s four major investor-owned utilities, was written into the grant as well.
"What they were proposing was consistent with what we thought made sense," David Rubin, director of service analysis at PG&E, told RMI. "Relying on clean energy and storage, and providing power to critical care facilities in case of an outage."
The goal is to develop more resilient buildings to support vulnerable populations in the face of natural disasters such as an earthquake.
SF Environment is leading the project with the engineering firm Arup acting as the primary subcontractor, and Celtic Energy and Strategen Consulting providing technical support and expertise. When Broomhead was writing the proposal to the DOE, he thought attending RMI’s eLab Accelerator would be a great way to move things forward.
So Broomhead, along with Rubin of PG&E, Russell Carr of Arup and Chris Lotspeich of Celtic Energy joined Accelerator to help San Francisco create a roadmap for deploying solar with storage for resilience both locally and nationally.
At the Rocky Mountain Instutute's eLab Accelerator, the team looked at 12 cases scattered throughout the city. It picked one to go into in detail to help set the stage for designing a microgrid.
The scene is Chinatown, and a big earthquake hits. Although many critical-care facilities in San Francisco have been earthquake retrofitted, the gas lines and electric lines both go out and may be out for greater than three days. Unfortunately, this happens during November when it’s often cloudy. How can the city keep an emergency shelter up and running with solar energy and storage?
After identifying key questions and criteria needed, the team created a decision tree for the technical design process, then tested the design process on a fire station as well. The decision tree asks certain questions about the load and if it can be met with solar plus energy storage on-site or off-site, then determines whether a microgrid or a facility-scale system, with or without a diesel generator, would be the best solution.
The team also developed schematic design options for three microgrid configurations that vary in who owns which aspects of the microgrid (customers, PG&E or the San Francisco Public Utilities Commission), and is developing a list of options for integrating existing private PV systems into post-disaster service. However, some of the most important lessons learned in Accelerator were not the technical details, but the bigger surrounding issues.
The big picture
According to RMI Manager Koben Calhoun, the eLab Accelerator team’s facilitator, eLab Accelerator helped the team step back and get a better understanding of what the primary issues are.
"It’s not always the technical details that come first, but the surrounding issues such as community needs, finance, regulatory, ownership, that really drive system design," said Calhoun.
Since Accelerator, SF Environment has had many follow-up conversations, which are still ongoing, with other stakeholders to work out financial and regulatory issues such as how it will be financed and who owns the on-grid assets.
While at eLab Accelerator, the team had a chance to sit down and talk with other teams that were dealing with some of the same issues.
"One of the best things to come out of Accelerator was meeting people from Ketchum and Hoboken," said Broomhead. "Our technical team learned a lot by leveraging the knowledge and experience of the other teams."
Now that some non-technical issues have been conquered, next steps include site visits, selecting the microgrid zone sites and figuring out the more technical details with PG&E and the other partners.
Shifting the paradigm
Everyone agreed that one of the best parts of eLab Accelerator was having all the players at the same table working toward a similar goal.
"We appreciate the city coming to us and looking at us as a partner,” said PG&E’s Rubin. "This project brings together two things PG&E greatly values, clean energy and resiliency. In case of a natural disaster, we want to be there for our community, our customers."
The project in San Francisco goes beyond just providing a microgrid to keep critical services up during a national disaster.
"The goal goes beyond San Francisco,” said Calhoun. "The city wants to create a model that other neighborhoods in San Francisco can follow, and a planning document that other cities around the country can use to do something similar."
Looking ahead, the goal is to cement a link between renewable energy and resilience.
"Our proposed project is not just key for emergency preparedness, but also for the grid and future energy system," said SF Environment’s Broomhead. "We start by creating a renewable energy system for the purpose of emergency back up power, and when people see we never have to run the diesel, the paradigm starts to shift. It shows that powering buildings with renewables is not only the environmental thing to do, but also the prudent thing to do."
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