The proposal would raise rates by 16.75%, 3.76% and 8.91% over three years. It follows an 18.85% increase that PSE put into effect this year. The utility serves about 1.2 million customers.

PSE says the added revenue is needed to meet Washington’s clean-energy requirements and address higher construction, equipment and energy-delivery costs, as well as challenges with permitting and changes to federal tax incentives. The company also says aging infrastructure must be replaced to maintain safe, reliable service.

Electricity demand across the Pacific Northwest could double or triple over the next 20 years, according to the Northwest Power and Conservation Council. Electrification of transportation and expanding technology-sector demand are among the factors expected to drive growth.

The rate case also includes a request to increase PSE’s authorized return on equity — the return the utility can earn for shareholders — from 9.9% to 10.8%. PSE is owned by Puget Holdings, whose investors include pension and investment organizations from Canada and the Netherlands.

Stephanie Chase, a research and communications manager at the Energy Policy Institute, said PSE’s investor returns are higher than the national average. She compared the investor-owned utility with Seattle City Light, a publicly owned utility that faces similar regulations but does not have the same shareholder structure.

Tyler Pepple, an attorney representing the Alliance of Western Energy Consumers, said the proposed increases are unusually steep. PSE investors recently reported returns of about 7.5%, he said, adding that utility investments are generally considered stable.

“Investors obviously want to maximize their return as much as possible,” Pepple said. “That still is quite a nice return if you are an investor in an enterprise like Puget Sound Energy.”

Washington Attorney General Nick Brown has directed the state Office of Public Counsel to challenge the proposed shareholder return before the Washington Utilities and Transportation Commission. Brown said the dispute concerns profit above the amount needed to cover utility expenses, not whether the company should earn money at all.

PSE has argued that its costs are being driven in part by clean-energy laws and rising expenses. Commission Chair Brian Rybarik said commissioners heard hours of testimony from hundreds of people describing how higher power bills are affecting household budgets. He said regulators must weigh customer costs against the need to attract investment and maintain the system.

The three-member commission is expected to issue a final decision in late January. Until then, the requested increases and shareholder return remain proposals, not approved rates.