The California Energy Commission exempted yet another very large diesel backup system from its permit certification process, putting the issue in the Bay Area Air Quality Management District’s court. The Commission also voted to allow two natural gas-fired power plants in Southern California to increase their output to meet peak demand when the heat soars.
The CEC votes came one day after state utility regulators mandated that 11.5 GW of non-fossil fueled power be online between 2023 and 2026 to increase the amount of non polluting grid reliability.
The unanimous Energy Commission vote cast at an unusual Friday meeting, instead of the usual Wednesday, exempted from its permitting the 96.5 MW diesel project at the Sequoia Data Center in the City of Santa Clara. The Commission found that the backup system will not have a significant impact on air quality after the applicant agreed to install only cleaner Tier 4 units, 54 of them, each 2.5 MW.
“We need to keep moving to cleaner backup and I look forward to not having to make these kind of decisions,” Commissioner Patty Monahan said.
State and Bay Area air pollution regulators earlier had argued that the CEC was undercounting emissions from the new backup system. The CEC then redid its analysis for Sequoia and required Tier 4 units, which produce 90% less nitrogen oxides and particulate matter than uncontrolled systems. These pollutants can cause cardiac arrhythmias and heart attacks, and respiratory effects such as asthma attacks and bronchitis.
The Bay Area air quality staff has not finalized the engineering analysis, which includes a health risk assessment, required as part of the permit for the Sequoia backup system, Erin DeMerritt, BAAQMD spokesperson said June 29.
In January, a Bay Area air district staff member pointed out to the CEC that there were 10,000 permitted diesel backup units in the region, compared to 7,000 systems just three years ago. Of those, 60 facilities have a combined 1 GW of diesel generation. Another 1.5 GW of diesel backup is being installed at data centers. These systems were found to run more often and far longer than expected.
Even worse, when the units are fired up during power outages or other emergencies, they are exempt from air pollution limits set in the air permits.
Intervenor Robert Sarvey told the Commission that instead of allowing this backup along with another 500 MW of diesel backup in poor polluted communities it should have approved 600 MW of demand response. He also noted that Microsoft was proposing to use natural gas at its backup system at its San Jose data center in place of diesel.
Microsoft plans natural gas backup
In a June 22 filing, Microsoft told the CEC it had concluded “that the use of natural gas generators for backup electricity is indeed feasible and can also allow the San Jose City Data Center to participate in voluntary load shedding/Resource Adequacy programs to assist in providing grid reliability.” Its application for a waiver from CEC licensing is pending.
Last July, Microsoft announced it ran a row of 10 racks of servers for 48 hours using a 250-kilowatt green hydrogen powered fuel system at is facility outside of Salt Lake City, Utah. Last week, Microsoft said it will use low-carbon renewable fuel to provide emergency power for its cloud service in Sweden.
Equivalent of 29,000 heavy duty trucks
In Oct. 2019, the California Air Resources Board found that 125,000 diesel backup units fired up during safety outages for roughly 50 hours. That resulted in about 126 tons of NOx and 8.3 tons of PM, which is the equivalent of 29,000 heavy duty trucks traveling 3,000 miles over a month.
Also pending before the Commission is a 96 MW diesel backup system at Amazon’s proposal Gilroy data center.
The Energy Commission has authority over diesel generation systems projects 50 MW or larger and may exempt ones less than 100 MW from the certification process. Diesel fuel is cheap, powerful, and usually widely available.
Power plant expansions okayed
The CEC also agreed last Friday to allow large generating facilities in Southern California to increase their production at times of high demand. The increases are not supposed to lead to a rise in monthly or annual emission levels.
The permit for the 560 MW El Segundo natural gas plant was revised to allow it to increase output by 30 MW.
The certification for the Walnut Creek Energy Center in the City of Industry under contract with Southern California Edison can now produce an additional 17 MW from power plant efficiencies to meet summer peak load.