Which power systems boost city resilience during power outages — and for how long?
Answering that question is one of the objectives of a report from American Council for an Energy-Efficient Economy (ACEEE), Community Resilience Planning and Clean Energy Initiatives
The report rates cities based on their resilience efforts, including investments in energy efficiency and renewable resources. The cities of Berkeley, California, Oakland, California, New York, San Francisco and Honolulu are among the cities identified as having strong resilience plans.
In the report, microgrids and solar plus storage systems are identified as providing high levels of resilience.
The report rates 66 city resilience plans selected from 100 Resilient Cities, an international program.
Diverse microgrids best
Climate change poses unprecedented challenges and disruptions, said the study. “In response, cities are actively planning to improve energy efficiency and promote renewable energy to make their neighborhoods more resilient in the face of climate change as well as other shocks and stresses.”
Microgrids that include solar, storage and diesel have a 90% chance of operating for about 3.5 days after an outage. That rate falls to 50% after 4.5 days, said the study.
Microgrids with only diesel generators don’t fare as well.
“Microgrids that only incorporate diesel generators have a less than 90% probability of surviving an outage that lasts more than two days and almost no chance of surviving an outage of three days or more because of uncertainties surrounding fuel resupply,” said the report.
Microgrid designs should include diverse resources – solar, storage, combined heat and power and diesel — to ensure that power supply is consistent, the report said.
Top city resilience efforts
The report cited the efforts of Berkeley and Oakland to provide resilience with microgrids.
Berkeley’s city resilience plan proposes a series of solar plus storage microgrids that connect both public and private critical facilities.
Oakland microgrid spans a city block
Oakland’s resilience plan addresses both supply and demand.
“In its EcoBlock pilot project, Oakland is creating a solar-powered microgrid that encompasses an entire city block. This project also includes deep energy retrofits in 30 low-income residential buildings on the block and the use of smart controls and on-site storage,” said the report. The plan is expected to operate the EcoBlock on near net-zero energy and cut emissions by 85%.
As part of the report’s efforts to identify the probability that resilience plans would work after an outage, solar plus storage systems were rated. Solar plus storage with diesel generators have a 90% chance of surviving a power outage for about 3.5 days, said the report.
They were especially effective in some parts of Puerto Rico after Hurricane Maria.
“In the hurricane’s wake, solar plus storage continued to generate electricity at San Juan’s VA Hospital, but the lack of power at other healthcare facilities, such as dialysis centers, led to an unnecessary loss of lives,” said the report.
San Francisco’s “Solar + Storage for Resiliency Project” is cited as another example of how communities can boost resilience.
The project, now complete, was designed to create a citywide network of buildings powered by solar plus storage.
“The project considered financial and technical feasibility, identified critical power needs, and studied how to size the system for maximum benefit,” said the report. It’s important to ensure that such systems are physically strong enough to withstand extreme weather conditions such as hurricane-force winds. It’s also a good idea to protect battery systems from water damage and flooding, the report said.
15 cities score high for energy efficiency
The report rated 15 cities’ plans as “exemplary or substantial” for energy efficiency. Of these, four were named exemplary: Athens, Buenos Aires, Honolulu and New York.
Those that earned a “substantial rating” are located in North America, South America, Europe, Africa, and Oceania, which suggests that efficiency is a global resource, said the study.
The report found that 13 cities have plans worthy of the “exemplary or substantial for renewable energy” rating. Of these, four got the exemplary tag: Chicago, Los Angeles, Honolulu, and New York.
Atlanta, Chicago, Honolulu, New York, the Santiago metropolitan area, and Washington, DC, are the only cities that earned at least a “substantial” rating for both energy efficiency and renewable energy.
Honolulu exemplifies how a city can take a comprehensive approach to energy efficiency.
The city’s current initiatives include a benchmarking ordinance for commercial buildings, a residential energy use disclosure ordinance, incentives to increase private uptake of electric vehicles (EV), and expansion of its EV charging network.
US cities best for renewable energy
All the cities awarded exemplary ratings for renewable energy planning were in the US, the report noted.
“By establishing and implementing robust clean energy initiatives, cities can become more resilient to disruptions in energy supplies and changes in energy use, regardless of the cause,” said the report.
Learn about microgrids and city resilience efforts at Microgrid 2020, June 2-3 in Philadelphia, Pa