AES Alamitos files supplemental application for 1,040-MW project in California

The AES Alamitos Energy LLC unit of AES Corp. (NYSE: AES) on Oct. 26 filed with the California Energy Commission a supplemental Application for Certification (SAFC) for the Alamitos Energy Center (AEC), to be located in the City of Long Beach, California, on an existing power plant site.

The AEC will be a natural-gas-fired, combined-cycle and simple-cycle, air-cooled facility with a nominal capacity of 1,040 MW. The AEC will be located on a 21-acre site within the existing power plant site, and will utilize to the extent possible existing infrastructure. The original AFC for this project was filed with the commission in December 2013.

“The AEC will meet the demand for new generation in the Los Angeles basin local electrical reliability area caused in large part by the closure of the San Onofre Nuclear Generating Station and anticipated retirement of over 4,000 MW of older, natural gas-fired generation currently using once-through ocean water cooling (OTC) by December 31, 2020,” said the Oct. 26 supplemental application. “The AEC will provide fast-starting and stopping, flexible, controllable generation with the ability to ramp up and down through a wide range of electrical output to allow the integration of intermittent, renewable energy into the electrical grid and enable attainment of California’s Renewable Energy Portfolio Standards (RPS).”

The AEC will be constructed on the brownfield site of the existing AES Alamitos Generating Station (AGS), and located on an approximately 21-acre site within a larger 71.1-acre parcel. Construction personnel requirements will peak at approximately 306 workers in July 2019, and to approximately 512 workers in January 2021, the application said. On average, the AEC will employ 191 construction personnel over the approximately 56-month construction period.

“In terms of ensuring electric reliability, the California Independent System Operator (CAISO) and the California Energy Commission (CEC) have recognized the importance of the AGS location as part of the coastal OTC fleet that provides both energy and capacity to satisfy the western Los Angeles Basin Local Reliability Area requirements (CAISO, 2011),” said the application. “The CAISO has identified a need for power generation facilities in the western sub-area of the Los Angeles Basin Local Reliability Area to replace the ocean water OTC plants that are expected to retire as a result of the [State Water Resources Control Board’s] OTC Policy (SWRCB, 2010).

“The results from the CAISO’s year 2021 long-term Local Capacity Requirements study estimates that between 2,370 and 3,741 MW of replacement OTC generation is required in the Los Angeles Basin to meet the future needs of the area. The requirement for replacement generation in light of OTC retirements in the Los Angeles Basin, along with other long-term transmission planning assumptions, is also confirmed in CAISO’s Once-Through Cooling and AB-1318 Study Results presented on December 8, 2011 (CAISO, 2011). CAISO also notes that many of the OTC facilities are in locations critical to local electrical reliability and repowered or replacement generating capacity with characteristics that support renewable integration in these same locations would provide both local capacity for reliability and essential grid support for a future with ever-increasing amounts of variable renewable energy.

“The effect of the repower/replacement OTC facilities reduces the number of total megawatts required compared to new generation developed elsewhere (CAISO, 2012). The California Public Utilities Commission (CPUC) confirmed the need for new generation in the Los Angeles Basin in a decision authorizing procurement of between 1,400 and 1,800 MW of new electrical capacity in the western Los Angeles sub-area to meet long-term local capacity requirements by 2021 and that at least 1,000 MW but no more than 1,200 MW must be from conventional gas-fired resources (including combined heat and power resources). Further, the CPUC found the following: a significant need for local generating resources to replace retiring OTC plants in the Los Angeles Basin local area under every scenario analyzed by the CAISO; that a significant amount of the 1,400 to 1,800 MW procurement be met through conventional gas-fired resources in order to ensure local capacity reliability needs are met; and that gas-fired resources at current OTC sites meet CAISO’s criteria for meeting local generating needs but other resources can also meet or reduce the local generating needs but may not be as effective (CPUC, 2013).

“As a modern, efficient gas-fired generation plant located at a critical grid location at an existing power plant site, the AEC will satisfy these resource and reliability needs. With the additional flexible fast start and stop characteristics of the technology employed, the AEC will also provide essential grid support as the electrical system integrates increasing amounts of intermittent renewable energy sources. In recognition of its critical grid reliability benefits, the AEC combined-cycle CTGs were selected by Southern California Edison (SCE) in its Local Capacity Requirements Request for Offer (LCR RFO) on November 5, 2014. The simple-cycle CTGs will meet the capacity needs anticipated to be identified in future procurement authorizations through the CPUC LTPP process.

“The AEC will consist of two gas turbine power blocks. Power Block 1 will consist of two natural-gas-fired combustion turbine generators (CTG) in a combined-cycle configuration, two unfired heat recovery steam generators (HRSG), one steam turbine generator (STG), an air-cooled condenser, an auxiliary boiler, and related ancillary equipment (collectively, AEC CCGT). Power Block 2 will consist of four simple-cycle CTGs with fin-fan coolers and ancillary facilities (collectively, AEC SCGT).

“The AEC CCGTs and SCGTs are unique assets that will provide greater reliability to meet resource adequacy needs for the southern California electrical system. As California’s intermittent renewable energy portfolio continues to grow, operating in either load following or partial shutdown mode is necessary to maintain electrical grid reliability, placing an increased importance upon the rapid startup, low turndown, steep ramp rate, and superior heat rate of the MSG configuration employed at the AEC. By using proven combined-cycle technology, the AEC CCGTs can also run as a baseload facility, as needed, providing greater reliability to meet resource adequacy needs for the southern California electrical system. As an in-basin generating asset, the AEC will provide local generating capacity, voltage support, and reactive power that are essential for transmission system reliability in the Western Los Angeles Basin sub-area and larger Los Angeles basin local reliability area.”

Units at the existing plant will be retired as the new units come on-line

The AEC will reuse, to the extent feasible, existing infrastructure including the existing SCE switchyard and transmission facilities; connections to the Southern California Gas (SoCalGas) natural gas pipeline system and City of Long Beach Water Department (LBWD) water connections; process water supply lines; and the administration, maintenance, and certain warehouse buildings.

The AEC will interconnect to the existing SCE 230-kV switchyard adjacent to the north side of the property. Natural gas will be supplied to the AEC via an existing offsite 30-inch-diameter pipeline owned and operated by SoCalGas. The AEC will require a new natural gas metering facility and construction of two new natural gas compressor buildings (one for each power block) within the AEC footprint. 

The demolition of the existing AGS units is not necessary for construction of AEC. Existing AGS Units 1–6 are currently in operation and will continue to provide essential electrical service concurrent with the construction of the AEC CCGT power block. Units 1, 2, and 5 will be retired after the AEC CCGT commences operation. Units 3, 4, and 6 will likely operate through at least Dec. 31, 2020. The city and AES have entered into a Memorandum of Understanding for the demolition of the existing units. Demolition of Units 1-6 will be conducted in accordance with the MOU once all necessary regulatory approvals to retire and decommission the existing units are received.

A portion of the AEC will occupy land formerly used for AGS Unit 7 (a peaking unit). The generating unit and much of the related facilities for former Unit 7 have been decommissioned, salvaged, and removed from the site. However, some components of the balance of plant for former Unit 7’s remain onsite, including certain buildings, foundations and balance of equipment including underground water, fuel and other lines, which will be demolished, along with two existing wastewater retention basins and a small maintenance shop to provide the necessary space for AEC.

The AEC CCGT will be located on the southernmost portion of the AEC site, on the former AGS fuel oil storage site, which was sold then reacquired by the applicant in late 2014. AEC CCGT will include the following principal design elements:

  • Two General Electric (GE) 7FA.05 CTGs with a nominal rating of 227 MW each. The CTGs will be equipped with evaporative coolers on the inlet air system and dry low oxides of nitrogen (NOx) combustors;
  • One, single-flow, impulse, down exhaust condensing STG with a nominal rating of approximately 229 MW;
  • Two heat recovery steam generators (HRSGs) of the horizontal gas flow, triple-pressure, natural-circulation type. Each HRSG will be equipped with a selective catalytic reduction (SCR) unit in the ductwork for the control of NOx emissions and an oxidation catalyst to control carbon monoxide (CO) and volatile organic compound (VOC) emissions, and the HRSGs will not employ supplemental firing;
  • One air-cooled condenser and a closed-loop fin-fan cooler;
  • Natural gas compressor;
  • One generator step-up (GSU) transformer per each GE 7FA gas turbine and one for the steam turbine; and
  • One 230-kV interconnection to the existing SCE switchyard, which is adjacent to the site.

The AEC SCGT will be located on the northern portion of the AEC site, adjacent to the San Gabriel River. The AEC SCGT will include the following elements:

  • Four GE Energy LMS 100 PB natural-gas-fired combustion turbine-generators (CTGs) with a nominal rating of 100 MW each. Each CTG is equipped with SCR equipment containing catalysts to further reduce NOx emissions, and an oxidation catalyst to reduce CO emissions;
  • Auxiliary equipment associated with each CTG will include an inlet air filter house with evaporative cooler, turbine inter-cooler and associated intercooler circulating pumps;
  • Two CTGs will share one fin-fan heat exchanger and one GSU transformer;
  • Natural gas compressors; and
  • One 230-kV interconnection to the existing onsite SCE 230-kV switchyard.

The AEC owner is AES Alamitos Energy, a wholly owned subsidiary of the AES Corp. Virginia-based AES Corp. is a global power company with generation and distribution businesses across five continents.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.