LOS ANGELES (August 26, 2020)–As part of California’s efforts to reduce Greenhouse Gas Emissions, LADWP participated in a statewide study to estimate leakage emission rates from large end-users of natural gas, including power plants. The release of small amounts of methane gas are a part of operating some natural gas power plants, other industrial facilities and fueling stations, and the study sought to determine the extent of such leaks to better inform statewide policymaking. While the study has not yet been completed, LADWP is acting on information it received early on to reduce methane released from its Valley Generation Station (Valley) as much as possible. The level of emissions detected in the study (100kg/hr) is considered low in comparison to numerous other emissions sources.
During the study, LADWP provided access to Valley to measure emissions that would lead to a better understanding of “fugitive emissions”, which are emissions that can occur at many industrial facilities, including power plants in the course of burning natural gas or other fossil fuels to generate electricity. Valley has both combined cycle and simple cycle natural gas units operating as part of LADWP’s power generation system, which made it an ideal candidate for the study. Data from both on-site and drone measurements was provided to LADWP in Spring 2020, which showed that the gas compressors at Valley were potential fugitive emission leak sources in the amount of 100kg/hr, when the plant was fully operational. In comparative terms, the amount of gas released at the Aliso Canyon Natural Gas Storage facility was 50,000kg/hr.
The emissions at Valley are considered incidental emissions that are not generally subject to regulation or permitting. The compressor units at Valley were completely overhauled in 2015, which included replacing all of the piston seals, thereby reducing emissions. Valley, along with Los Angeles’ three coastal power plants, generally run only when needed to supplement imported power or support electrical voltage in the LA Basin.
However, based on the findings in the Spring 2020 report, LADWP put a plan in place to repair the equipment as quickly as possible. The engineered materials needed for the repair are scheduled to arrive in October, with the repairs slated for November when a shutdown of Valley could be done without jeopardizing the electrical grid and potentially causing widespread power outages. Equipment at power plants are often repaired by utilities when units can be safely taken out of service during cooler weather months, when electricity demand is low, and power supply can be obtained through other power plants.
Late last Friday, we were contacted by staff at Jet Propulsion Laboratory to inform LADWP that data from recent airborne remote-sensing surveys of the LA basin conducted as part of its Greenhouse Gas monitoring program detected methane near Valley Generating Station. The methane was observed during JPL’s most recent overflights on July 16, 2020 and August 7, 2020, between the hours of 1 and 2pm. They also informed us of an aerial observation that occurred in 2017 as part of a study they were conducting for the California Energy Commission. This observation by JPL was not previously known by LADWP.
In subsequent discussions, JPL indicated that its report had found 600 methane emitters statewide and that Valley was found to be one of the smaller emitters and is not considered a high priority methane source.
Based on the JPL observations, LADWP is expanding its existing air quality and compliance monitoring at Valley to specifically target the compressor emissions. We will report the findings publicly.
Though the methane emissions are considered low, we are very sensitive to the concerns of local residents in the Northeast Valley and want to assure the community that LADWP is working on immediate interim steps to address the situation, including undertaking temporary repairs to reduce leakage from the compressor equipment, control of methane leakage through onsite capture and treatment, and minimizing usage of Valley to the extent possible.
Additional Resources:
For more information on the California Energy Commission / CA Air Resources Board / CA Natural Resources Agency Report, prepared by Jet Propulsion Labs, please see:
The California Methane Survey, Prepared by JPL, July 2020
Pages 35-36: Power Plants The team surveyed 238 natural gas-fired power plants in the state – an estimated 55 percent of all such facilities – including an intensive campaign during a heat wave in Los Angeles to assess the potential for additional fugitives during peak demand periods. Plumes at only seven such facilities were observed. While some of the observed emissions are larger than those reported to the EPA (Figure 23), the team concluded that this is not a major methane emitting sector for California – collectively responsible for about 2.1 percent of total emissions from the population of point sources.
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