Wyoming’s largest utility today began participating in a new “Extended Day Ahead Market” for electricity on the Western grid, a potentially landmark shift in the way energy is sold in the state that could lower rates as energy costs soar.
The new market, which went live Friday, gives Rocky Mountain Power, a subsidiary of PacifiCorp, and other utilities and power producers across the West access to more buyers and sellers. It also allows them to meet forecasted demand with electricity produced elsewhere in the region.
The new system runs on the network of the California Independent System Operator (CAISO), which manages the flow of electricity in the Golden State. But it will be overseen by an independent board of electricity experts from across the western U.S.
PacifiCorp began trading in the market Thursday night after a period of simulations to fix bugs and assess how the expanded market’s prices, demand and supply all interacted. Thursday’s purchases were delivered Friday, CAISO and the company announced on a press call. PacifiCorp will be “the first participant alongside CAISO” in the market, according to Omar Granados, a spokesperson for the utility company.
“We expect even greater reliability and affordability benefits for customers as the market grows,” said Elliot Mainzer, CAISO’s president and CEO.
At a February hearing before Wyoming’s Public Service Commission, Michael Wilding, vice president of energy supply management at PacifiCorp, estimated that the company then satisfied about 3 to 5 percent of its generation and demand through broader market purchases. Under the day-ahead market, that number will be 100 percent.
Revenue from any sales and money saved by using cheaper power “will be reflected in lower net power costs, which will flow through to our customers,” Wilding said.
Power bills have been rising across the U.S. for years, lately driven in part by electricity-hungry data centers that power AI. In Wyoming, electricity bills rose by 5.5 percent from 2024 to 2025, according to Energy Information Administration data.
Brian Turner, a senior director with Advanced Energy United, an energy trade association, said the Extended Day Ahead Market will streamline power transactions in the West. Prior to the new market, Turner said, Western utilities usually filled excess demand as needed from a handful of other power producers they were already familiar with; there was no simple way to access a wider pool of buyers and sellers.
The new market could confer advantages to both utilities and consumers simply by being larger. “It allows for a lot more transparency, a lot more liquidity to the market,” Turner said. “There’s more buyers and sellers, and you can find your cheapest price.”
PacifiCorp will participate as both a buyer and a seller. If the company believes it has cost-competitive power, it can sell it in the market. Conversely, if it’s expecting a spike in demand and seeks cheaper options to satisfy it, it can scour the market for better prices. In either case, participation is voluntary.
“It’s really going to be driven by economics and local policy,” said Turner, who helped establish the Regional Organization for Western Energy, which will oversee the Extended Day Ahead Market.
In Wyoming, the state’s Energy Authority, a quasi state agency, will monitor PacifiCorp’s participation in the market for its first five years using data provided by the utility to track whether Wyoming’s coal, oil and gas sectors are being “unfairly penalized” by climate targets in California, Oregon and Washington, said John Jenks, the authority’s director of energy market development.
Long one of the nation’s top fossil fuel producers, Wyoming has leapt at Trump administration directives to boost fossil fuels, a more expensive source of new generation than wind and solar. While batteries make it easier for renewables to serve as base-load power, Jenks said the ability of fossil fuel power plants to ramp up their generation regardless of the weather made him “optimistic that Wyoming will continue to be an important player in reliability.”
“For a state like Wyoming, energy policy is our lifeblood,” Jenks said. “We just want to make sure that whatever’s happening is not going to adversely affect our economic development goals.”
The new market comes as energy prices skyrocket due to the war in Iran, and it may help insulate consumers from such economic shocks, Turner said. Since the U.S. and Israel first struck Iran in March, the cost of oil has spiked, pushing up prices at the gas pump and reverberating through other sectors of the economy.
“When the price for natural gas goes up, [utilities] still got to meet their demand with those generators, and so they’ve got to pay that price. And then they’ve got to pass that on to ratepayers,” Turner said. “But if they had a big market where, say, solar energy from Nevada or Idaho or Arizona is very cheap, … Wyoming can import that instead of having to pay whatever the high natural gas price is at any given time.”
It is unlikely such a market mechanism would fully exempt Western power consumers from price shocks emanating from the Middle East.
The Extended Day Ahead Market is the first such market in the West. The regional transmission organization Southwest Power Pool is creating another marketplace, initially with power producers in Arizona, Colorado and the Northwest.
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Jake Bolster reports on Wyoming and the West for Inside Climate News. Previously, he worked as a freelancer, covering climate change, energy, and the environment across the United States. He holds a Masters in Journalism from Columbia University.
