LAWAI, Kauai — A new solar generating plant capable of producing and storing power in daylight and then releasing it at night will be partially dependent on 300 sheep.

The plant was commissioned Jan. 8 by the Kauai Island Utility Cooperative and pushes the utility over the 50 percent mark in terms of the amount of its power that comes from renewable sources.

It’s the second such plant put in service by KIUC and, according to David Bissell, the co-op’s CEO, it is currently the largest such installation in the world. That’s a distinction which, in a rapidly evolving industry, it’s unlikely to have for long.

KIUC believes it is now the most advanced utility in the country in the context of producing electricity from alternative sources that can serve customers virtually around the clock.

The sheep are the lowest-tech component of the new solar farm, deployed on the 155 acres of former sugar plantation fields the plant occupies. The solar panels, which can change their angles automatically to track the sun throughout the day, need to be kept clear of vegetation. Beginning with their arrival this week, that’s the sheep’s job.

Kauai Island Utility Cooperative’s new solar plant in Lawai was commissioned Jan. 8. AES Distributed Energy

KIUC introduced its first timed-release solar plant in 2017, partnering with Tesla, whose batteries it uses. For the new 28-megawatt plant in Lawai, the batteries packs are from Samsung and are capable of storing 100 megawatts of power. In all, this one plant produces enough to supply 11 percent of Kauai’s total electric power needs over any given 24-hour day.

For up to five hours after sundown, KIUC’s solar-battery power resources can supply 40 percent of all island power needs. The storage capacity also covers for random drops in power generation caused by clouds.

KIUC has so much solar capacity that there are frequently days when fuel-powered generators in Port Allen and Kapaa don’t need to be run at all.

Workers adjust the batteries at the Kauai Island Utility Cooperative Solar plant in Lawai. Allan Parachini/Civil Beat

Bissell said the utility has reached the 50 percent mark in terms of total renewable power — a total that includes solar, hydro and biomass generation — 10 years earlier than it projected as recently as a couple of years ago. It also puts KIUC more than a decade ahead of state objectives for integrating renewable electricity.

Under a law enacted in 2015, Hawaii’s targets for renewables are to reach 30 percent statewide by 2020, 40 percent by 2030 and 70 percent by 2040. Bissell said that with the solar capacity KIUC now has, as well as yet another solar-battery plant that is to be constructed starting later this year on the grounds of the U.S. Navy’s Pacific Missile Range Facility, the utility will hit 60 to 65 percent renewable power by 2020 — nearly 20 years ahead of state guidelines.

In theory, Bissell said, KIUC could even reach 100 percent renewables within a decade, but “we’re not going to do that just for the sake of doing it.” He said KIUC has no plans to retire any of its diesel- and naphtha-powered conventional generators because the island’s isolation requires the utility to retain the ability to back up all of its power needs by conventional means.

David Bissell, left, the CEO of KIUC, and chief engineer Brad Rockwell at the new Lawai plant. Allan Parachini/Civil Beat

All of this has not escaped notice in the utility industry. The Washington-based Smart Electric Power Alliance, a trade group, ranked KIUC first nationally in terms of the amount of electricity per customer that its system can store in batteries for release as needed.

Tiny KIUC can store more than 37 times as much electricity per customer as giant Southern California Edison, according to SEPA’s rankings.

KIUC ranked fifth nationwide in terms of the total megawatts of power it can store — behind only four enormous utilities that include Southern California Edison, San Diego Gas & Electric, Tucson Electric Power and Pacific Gas & Electric. KIUC, in fact, is capable of storing only three megawatts of power less than PG&E, one of the largest utilities in the world, SEPA’s ratings say.

Hawaii’s Maui Electric ranked third in power stored per customer and ninth in total power storage capacity nationally.

The new plant’s solar panels tilt to follow the sun. Allan Parachini/Civil Beat

“The solar PV plus storage systems KIUC has deployed in 2017 and 2018 are some of the first in the country to be ‘full-sized,’ which means the battery’s energy capacity is of equivalent size to daily solar energy generated,” said Nick Esch, a spokesman for SEPA. “In short, these projects are some of the first solar power plants in the U.S. to be fully dispatchable,” meaning the power can be stored for use when needed, not just the instant it’s generated.

The Lawai plant was built and is owned by AES Distributed Energy, a national energy producer. It was constructed based on a long-term power purchase agreement under which KIUC pays 11 cents per kilowatt hour, making it second only to hydro generation (5 to 6 cents) as the cheapest source of electricity on Kauai.

The cost reflects rapid advances in the cheapening of solar power. KIUC’s first two large solar plants, which have only minimal battery backup, deliver power for 12 to 13 cents per kilowatt hour, while the Tesla solar-battery plant’s electricity is priced at 13.9 cents. For perspective, power generated by Kauai’s single biomass plant is double that price.

Bissell cautioned co-op members, however, not to expect bills to drop anytime soon. KIUC’s strategy for the future, he said, is to continue the rapid embrace of some of the country’s most innovative electrical technology and still hold today’s costs and bills essentially unchanged for the next decade or more.

Disclosure: Allan Parachini worked as a communications consultant to the Kauai Island Utility Cooperative for six months in 2016.

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