The Kauai Island Utility Cooperative is proposing the state’s first significant expansion of hydroelectric power generation in decades with a series of planned projects that could provide nearly 20 percent of the island’s power needs.

KIUC has partnered with Massachusetts-based Free Flow Power Corp. to explore the development of four hydroelectric projects on rivers and streams across Kauai that could generate enough electricity to power roughly 13,000 homes.

The development of hydroelectric power generation in Hawaii has thus far taken a back seat to solar and wind power in the recent push toward greater use of renewable energy sources. The last major hydroelectric project in the state was built on the Big Island’s Wailuku River in 1993. Many of the other plants date back to the early part of the 20th century.

The dozen or so hydro projects spread around the state have a total generating capacity of about 30 megawatts — 15 megawatts on the Big Island, 9 megawatts on Kauai and 6 megawatts on Maui. The total is equal to the peak output of the wind farm recently completed in Kahuku.

KIUC’s plans would add another 24 megawatts of hydroelectric generation from facilities planned for the Hanalei, Wailua and Makaweli rivers as well as at the Kokee Ditch, according to applications filed with the Federal Energy Regulatory Commission. KIUC issued a news release last week to announce the filings made with FERC in October and November.

The estimated 80,000 megawatt-hours of electricity generated by the plants would amount to 18 percent of Kauai’s total energy consumption.

"Hydroelectric power is a unique opportunity — it’s low cost from day one," said Steve Rymsha, senior energy solutions engineer for the nonprofit, member-owned utility. "It’s a very economical, stable source of electricity."

The utility estimates that its cost to generate electricity from the hydro projects will run about 12 cents to 15 cents per kilowatt-hour, compared with 20 cents per kilowatt-hour from its oil-fired generators. The savings to KIUC would be passed along to its members, said company spokesman Anne Barnes.

Besides cost, another advantage hydroelectric has over wind and solar as a renewable energy source is that the power is considered to be "firm." Both wind and solar present problems for utilities trying to maintain the stability of their grids because of factors like fluctuating wind speeds and availability of sunlight.

The Hanalei River, Makaweli River and Wailua River proposals involve constructing dams and weirs that would result in reservoirs of various sizes. The largest would be a reservoir with a surface area of 35 acres that would be created by a 503-foot-long, 23-foot-high earthen dam on the Wailua River. The Kokee Ditch project would tap two existing reservoirs that would be upgraded, Rymsha said.

The Wailua project has raised concerns in the community because of its close proximity — about 1,000 feet upstream — from Wailua Falls.

In a letter to FERC, Judy Dalton of Lihue said she was worried that the impeding the river’s flow would adversely affect "one of the most popular visitor destinations on Kauai."

"Putting a dam upstream of the falls would interfere with and impede the flow of water. As a result it would lessen Wailua Falls’ beauty that has inspired visitors for eons."

Several other residents who submitted written comments on the Wailua plan suggested developers opt for a "run-of-the-river" approach, where the natural flow of the river could be tapped to generate electricity without building a dam. The majority of existing hydro projects in Hawaii are run of the river.

KIUC emphasized that the proposed hydroelectric proj-ects are early in the planning stages, and the process of conducting environmental reviews, permitting and obtaining land rights could take "several years."

One issue KIUC will have to deal with is a competing plan for a hydroelectric plant along the Kokee Ditch on the west side of the island. An association of local farmers has teamed up with another alternative energy company to propose a hydroelectric facility in the area.

The Kekaha Agriculture Association filed a motion with FERC to intervene in the case, saying the plan it is pursuing with Pacific Light & Power Inc. "takes into account the best interests of the Kauai agricultural community and the larger agricultural community of the state of Hawaii." The partnership would sell electricity to KIUC under a power purchase agreement.

Under the KIUC proposal, however, the utility would own the power plant and therefore would be able to get a better price for the electricity, Rymsha said.