The Moss Landing Power Plant is a natural gas powered electricity generation plant located in Moss Landing, California, United States, at the midpoint of Monterey Bay. Its large stacks are landmarks, visible throughout the Monterey Bay Area. The plant is owned and operated by Houston-based Dynegy and currently has a generation capacity of 1020 MW (net) from its two combined cycle generation units. It was once the largest power plant in the state of California, with a generation capacity of 2560 MW, before its two large supercritical steam units were retired in 2016.
It is to be the site of a new battery storage power station for grid battery storage of over 567 MW / 2,270 MWh of power, potentially the world's largest when completed.
History
In 1949, Pacific Gas & Electric (PG&E) began construction on the Moss Landing Power Plant. Five natural gas and oil powered steam units were built during the 1950s. Commercial generation started in 1950 with a capacity of 613 MW.
In 1964, the construction of two additional units began (6 and 7), with two new stacks. These two units had a capacity of 750 MW each for a total of 1500 MW, with tall boilers. They employed a newer technology using supercritical steam at .
In 1995, the original five units were retired, and in 1997 PG&E let the permits lapse for these units.
As part of the Deregulation of Utilities in California, PG&E sold the plant to Duke Energy (DENA) in 1998. To comply with more restrictive pollution regulations, units 6 and 7 were upgraded in 1998 with a selective catalytic reduction unit and digital control systems.
Starting in 2000, the eight stacks and 19 fuel oil storage tanks were removed, and two new units were built on the former site. The new units 1 and 2 were brought online in 2002. They are combined cycle units, 50% more efficient than the other units, because they use two turbines: first, a pair of 170 MW gas turbines, then a 190 MW steam turbine, for a total of 530 MW each. When completed in 2002, the plant was the largest power plant in California by capacity, at 2560 MW.
In 2006, having invested over half a billion dollars in upgraded capacity, efficiency and emission control, Duke Energy sold the plant to LS Power Equity Partners. Dynegy then purchased the plant in April 2007 along with other assets of LS partners.
In 2015, a transmission tower collapsed at the power plant, causing a major Monterey County area power outage.
On December 31, 2016, Dynegy retired supercritical steam units 6 and 7 as they were no longer economically competitive. However, Dynegy continues to maintain the permit on these units.
In February 2017, independent power producer Dynegy, Inc. announced that it may close the gas plant, due to market conditions resulting from a glut of wholesale electricity capacity in California making it difficult to operate profitably. By 2018, California had 7,000 MW of surplus generating capacity, but a similar amount (mostly ocean cooled) would be retired by 2021. The glut in electricity capacity is partially a result of policies which guarantee utilities like PG&E (a regulated monopoly) a return on investment for building new power plants, even when they are not needed. Independent power producers like Dynegy, on the other hand, do not have a guaranteed return on their investment. Power production has dropped considerably, reducing taxes paid to Monterey County.
Grid connection
The plant has power lines that connect it to Path 15, and interconnections like Path 26 and Path 66 that allow power to flow to far-away regions. The plant is also connected to local loads and the San Jose region by transmission lines.
Gas units
Both the supercritical units and the combined cycle units use once-through cooling. The supercritical units have a cooling requirement of per minute, and the combined cycle units a requirement of .
Supercritical Steam Units 6 and 7
Units 6 and 7 used supercritical steam. These units were retired at the end of 2016. At the end of their life, units 6 and 7 were typically operated as peaking units when demand for electricity was highest. In 2016, the last year of operation, they only operated approximately 3% of the time.