Solar, pumped hydro project to help KIUC meet peak evening loads

A problem with solar power is that, on many days of the year, the amount of it generated begins decreasing just as load is peaking in the late afternoon.

An electric power cooperative on the island of Kaua‘i in the state of Hawai‘i recently announced a project meant to help it overcome that problem.

The West Kaua‘i Energy Project would use solar generation, pumped-storage hydropower and storage batteries to meet 25 percent of Kaua‘i’s total electricity needs, make the power on Kaua‘i’s grid 80 percent renewable and enable the island to run solely on renewable energy for prolonged periods without sunlight.

When operational, the project’s solar generation and pumped-storage hydropower would contribute up to 35 megawatts of power directly to the grid on Kaua‘i and store up to 240 megawatt hours of electricity for dispatch during the evening peak load on the island.

The project would be built and run by The AES Corporation for the Kaua‘i Island Utility Cooperative (KIUC). The Arlington, Va.-based energy giant already has completed two solar + storage projects with KIUC and has more than 200 MW of solar, solar + storage, and wind projects in operation or under development in Hawai‘i.

For the project, three existing reservoirs and their related ditch system infrastructure would be rehabilitated. Additionally, the historic diversion structures in Kokeʻe would be modified to restore and increase flow to the Waimea River (pictured above).

KIUC and AES said environmental studies for the project have been ongoing and a draft environmental assessment is expected to be filed with Hawai‘i's Department of Land and Natural Resources this quarter.