Hawaiian Electric, Wailuku River Hydroelectric want to continue providing reliable, sustainable, renewable energy to Big Island

For 30 years, Wailuku River Hydroelectric has harnessed the waters of the Wailuku River to provide up to 10 megawatts of clean, renewable and reliable energy to the Big Island power grid.

The facility owner — Iowa-based BHE Renewables, a Berkshire Hathaway Energy business —provides as-available energy to Hawaiian Electric for the power grid through a state-approved purchase contract.

But that purchase contract was set to expire on May 12. Talks began last year to negotiate a new long-term amended agreement. Until a new agreement is reached, however, Hawaiian Electric and the hydroelectric plant have asked the Hawai’i Public Utilities Commission for an amendment to the existing contract to extend it up to five years. The proposed amendment also asks for a new lower rate to purchase the hydroelectric power that could provide savings to Big Island electricity customers.

To enable the continued sale of the hydro-produced energy while it considers the proposed amendment, the Public Utilities Commission on May 11 issued an order allowing Hawaiian Electric and the Wailuku facility to operate under the terms of the current contract.

BHE Renewables hosted a public meeting Wednesday in Hilo to share the facility’s history and discuss opportunities for its continued use.

The Wailuku plant began operations in 1993 and is the largest hydroelectric facility on the Big Island, using the natural flow of the river to produce electricity through two hydraulic turbine generators. From 2018-22, the facility provided between 2.1% and 4.9% of the island’s annual electric system generation.

Wailuku River Hydroelectric is located about 2 miles mauka, or mountain side, from Downtown Hilo. It sits at the junction of the Wailuku River and the north and south forks of the Kalohewahewa Stream, above Boiling Pots, a series of large pools of rolling and bubbling waters on the river connected by underground flow or cascades within Wailuku River State Park, and ‘Akōlea Road.

The hydroelectric powerhouse is fed by the Wailuku River and its watershed, which includes the streams that feed into it. The facility operates without dams and other obstructions and is about 2,000 feet above sea level.

Up to 1,200 gallons per second can flow over a span of 4 miles to the powerhouse. At full tilt, that’s enough to power 13,752 homes. The flow rate normally runs at about 375 gallons per second, which can power 3,300 homes on average. The power generated gets to the grid via a 1-mile, 69-kilovolt transmission line at an interconnect near ‘Akōlea Road.

“While variable due to its dependence on high elevation rainfall, the facility’s output is stable and persistent when producing, without the variability of wind or solar,” Hawaiian Electric’s application for the amendment says. “Hydroelectric energy is potentially available through all hours of the day … including during peak and nighttime hours, and provides an independent, complementary and/or alternative renewable energy resource.”

The Wailuku River is a sustainable natural resource that never goes away, said BHE Renewables Vice President of Communications and Public Relations Dan Winters during his presentation Wednesday evening. Because of its reliability and sustainability, Hawaiian Electric can be strategic about how to deploy its resources, especially when grid issues or other circumstances reduce generation.

The water used remains in the Wailuku watershed, as the powerhouse uses only the flowing waters of the river and streams it sits on and doesn’t take more. Conservation flows remain at all times, which are monitored and reported monthly to the state, and all of the water used to generate electricity is returned to the river immediately downstream from the powerhouse unchanged, meaning the water quality is not diminished.

Winters said the water retains its “crystal clarity” above and below the hydroelectric facility.

“We want to continue providing that clean power to Hawai‘i Island,” he added.

Wailuku River Hydroelectric also produces energy in a safe and secure manner, the company said. The facility is monitored by surveillance cameras and behind locked gates to limit vehicle access and prevent disturbances to the natural habitat. The facility is maintained by Hilo-based company Power Generation Services, which employs 10 Big Island residents.

The proposed amendment not only seeks a five-year extension of the existing contract, it also calls for Hawaiian Electric to be able to purchase the energy generated by Wailuku River Hydroelectric at 7 cents per kilowatt hour during the interim. That is 44% lower than the historical average rate of about 13 cents per kilowatt hour and 71% lower than the 24 cents per kilowatt hour average in 2022, when fuel prices increased because of geopolitical risks.

The previous power purchase agreement, like most from that time, charged the utility a rate based on the price of diesel fuel. The proposed interim rate would be fixed and not affected by the unpredictability and volatility of fossil fuel prices.

That lower rate and less volatility would translate into savings for Big Island electric customers, which could see bill savings as early as this summer. However, that still would depend on the island’s electricity generation mix at the time and oil prices.

“For more than a century, run-of-river hydroelectric has been part of the diverse mix of resources that power Hawai‘i Island,” said Hawaiian Electric Vice President of Resource Procurement Rebecca Dayhuff. “We value our long-term partnership with Wailuku River Hydroelectric.”

During Wednesday’s public meeting, a person asked if the extension of the agreement would include additional development or construction at the Wailuku site and if the process or equipment the facility uses to generate power has changed since the early 1990s.

Officials said no new development of the property is proposed and how the plant generates power and the type of equipment it uses has remained the same.

BHE Renewables operates in 11 states, with a combined generation capacity of nearly 5,200 megawatts. That includes electricity generated through solar, wind and geothermal plants —and its hydroelectric facility on the Big Island.

Anyone who wants to comment on the proposed amendment to the power purchase contract or has questions can contact BHE Renewables via email at info@bherenewables.com or the Hawai‘i Island Economic Development Board at 808-935-2180 or hiedb@hiedb.org.