The Los Angeles Department of Water and Power (LADWP) is embarking on a groundbreaking hydrogen generation project.
The public power utility plans to phase out the 1,800 MW, coal-fueled generation at the Intermountain Power Project (IPP), which it participates in with electric power cooperatives and other public power utilities in California, Nevada and Utah, and replace it with natural gas-fueled generation that would eventually be fueled entirely by hydrogen. In addition to generation, the IPP also includes two large transmission systems that move power throughout the region and to Southern California
The driving factor behind the decision for LADWP to shut down the coal facility and replace it with another generation source was the city’s adoption of a target to be powered by 55% renewable energy by 2025 and be powered 80% by renewable energy by 2036. In addition, Los Angeles, like the rest of California, faces a target of being powered 100% by clean energy by 2045.
“If you look at reality, there is no way to get to 100% renewable energy without hydrogen in the mix; it just doesn’t exist,” Marty Adams, LADWP’s General Manager and Chief Engineer, told the utility’s board of commissioners this month.
The coal-fueled Intermountain plant in Delta, Utah, began operating in 1986. It is scheduled to close in 2025. Project participants have been working on a repowering plan for Intermountain since 2010. In 2015, Project participants decided to replace the plant with 1,200 MW of natural gas generation, but LADWP and the other participants in 2017 decided that they only needed an 840 MW plant.
There are two main factors driving the decision to stay with a fossil fueled plant. One is the need to have a generation source that can integrate increasing amounts of renewable energy into the grid; the other is the need for “a dispatchable rotating mass” to support a 500 kV high voltage direct current (HVDC) line that runs from the plant and provides Southern California with 2,400 MW of capacity, Paul Schultz, LADWP’s director of Power External Energy Resources, said.
The HVDC requires continuous power to operate at full capacity. Therefore, the generation component is essential to keep the transmission system online.
In addition to generation from the IPP, the HVDC line also serves as a conduit to move renewable energy to California load centers. It currently connects with about 400 MW of wind power, but it could serve as a renewable energy hub in the future. There are already 2,300 MW of solar interconnection requests in the queue, and LADWP is in discussions with entities to bring as much as 1,500 MW of wind power down from Wyoming.
Intermountain’s role as a renewable energy hub, and its unique location, are central to the plan to convert the plant to burn hydrogen. The hydrogen to fuel the plant would have to be manufactured through electrolysis, a process where water is separated into its two constituents, hydrogen and oxygen. The process would be powered by renewable energy provided through Intermountain’s transmission systems. Running that process using renewable energy helps reduce the overall emission profile of the repowering project. It could also help with the economics of the project as renewable power that might otherwise be curtailed.
Burning hydrogen does produce nitrogen oxide, but it does not produce carbon dioxide. The generator’s heat recovery steam generator would be sized to increase air flow and help reduce emissions from the plant, Schultz said. LADWP is also discussing carbon capture technologies with several vendors. LADWP says that based on technology of the turbine manufacturers, the generators are expected to have the capability of burning a fuel mixture of 30% hydrogen when it begins operating in 2025.
Design and procurement for the repowering project has already begun and is expected to be completed in July 2025. In addition to building the new power plant, the project also calls for replacing the HVDC converters that are reaching the end of their useful life.
In all, the total cost of the project, the generation and HVDC converters is $1.9 billion, Schultz said. The hydrogen conversion equipment would be a separate cost. LADWP is exploring “working with partnerships” to that portion of the project and is not yet ready to go public with a cost estimate, Schultz said. One possibility would be to secure funding through a Department of Energy grant, he said.
Converting the generation equipment to gradually increase the hydrogen burning capacity would be an “incremental capital cost” and could be coordinated with regular turbine maintenance schedules, Schultz said.
Further out, LADWP is also looking at the potential at the IPP site to store hydrogen. The plant is located on top of a large geologic salt dome, the only one in the Western United States. A single cavern at the site could store hydrogen equivalent to 84 times as much energy as a 1,200 MWh battery system and store that energy for months at a time. The site has the potential for 100 caverns, LADWP said.
Storing hydrogen at the Intermountain site would allow for “seasonal shifting” that could provide arbitrage opportunities to defray the costs of hydrogen production, by manufacturing hydrogen when energy prices are low and using it to generate power when prices are high. The utility is also looking at the caverns to support a 160-MW compressed air energy storage generating plant.
The current energy-in, energy-out roundtrip efficiency of the renewable hydrogen process is about 30% to 35%, Schultz said, but noted that calculation does not take into account other factors such as the policy mandates the utility must comply with and other potential costs such as the potential for forced renewable energy curtailments.
“We are very excited about the opportunity to take a leadership role with this project,” Schultz said. When completed, the project would be the largest commercial scale hydrogen generating plant in the world.