Microgrid benefits attractive to isles

There is a growing interest in microgrids on the mainland among businesses and government facilities that see the small-scale power production and delivery systems as a way to ensure the quality of their electricity and protect themselves from prolonged outages like the one Superstorm Sandy inflicted on a wide swath of the East Coast last year.

The microgrid concept is also beginning to attract attention in Hawaii, but more for the potential of such systems to tap the state’s abundant renewable energy resources and provide a hedge against the high cost of utility-provided power.

The military is already experimenting with aspects of microgrid technology at bases in Hawaii. In the private sector, Lanai has been targeted for a microgrid as part of major improvements planned by the island’s new owner, software mogul Larry Ellison. The consultant Ellison hired to overhaul Lanai’s energy project is a University of California at San Diego executive who oversees the school’s world-renowned microgrid. Parker Ranch on Hawaii island also is studying the possibility of building a microgrid as a way to reduce its hefty electricity bill.

At the heart of sophisticated microgrids like the one at UC San Diego are computer software and remote measuring devices that allow the systems to generate, store and dispatch energy with an ease that only utilities were previously capable of achieving. Microgrids optimize the use of locally generated power from both renewable and traditional sources while keeping the option of being tied to a utility grid. When a local area is short of power, the microgrid can draw from the utility. When the microgrid is producing excess power, it can export it back to the utility. And when a natural disaster knocks out the utility grid, the microgrid can disconnect and power itself.

Distributed energy sources such as rooftop solar, wind turbines and fuel cells create difficulties for utilities as they try to manage the constantly changing supply of power across their grids. Microgrids help solve that problem by consolidating the various power sources into a single profile that the utility can more easily deal with, said Chris Marnay, a retired Berkeley Lab scientist who has been researching microgrids for more than a decade.

From the power consumer’s side there are several different motivations for forming a microgrid. Businesses such as data centers and semiconductor manufacturers that can’t afford to be hit with power spikes or brownouts can benefit from the power security and reliability that microgrids provide, Marnay said.

"Other motives may be more low-tech, like a sewage treatment plant that generates methane and wants to convert it into electricity that it can sell to the utility," Marnay said.

Another common motive is "the desire to be green," he said.

Then there’s cost.

"When electricity is 40 cents a kilowatt hour like you have in Hawaii, a microgrid makes sense," Marnay said.

That was the impetus for officials at Parker Ranch on Hawaii island to hire a team of consultants to determine whether the 130,000-acre ranch could meet its energy needs with a microgrid fueled by renewable sources and have enough power left over to supply the neighboring town of Waimea.

The three-company consortium of Siemens PTI, Pace Global and Booz Allen Hamilton was selected in September and tasked with producing an integrated resource plan that will evaluate the ranch’s energy resources and recommend the best way to deploy them, said Neil "Dutch" Kuyper, Parker Ranch president and CEO.

Parker Ranch has good potential for wind, solar and biomass development, according to Kuyper. One of the ranch’s unique assets is an elevation change of 7,000 feet that could support a type of energy storage called pumped-storage hydropower.

Pumped-storage projects usually feature two reservoirs at different elevations. During times of low electricity demand, such as late at night and into the early morning, wind power is used to pump water to the upper reservoir. When power is needed during high-demand periods, the water in the upper reservoir is released through turbines that generate electricity.

Energy storage systems are a key component of any microgrid, smoothing the output of renewable energy sources such as wind and solar, and providing backup power.

Many mainland microgrids take care of energy storage using batteries, which can be expensive. Pumped storage, by comparison, is relatively inexpensive.

Pulama Lanai, the entity formed to operate Lanai for Ellison, has cited pumped storage as one of the technologies it will consider as part of its plan to modernize the island’s electrical grid. Lanai’s power system currently consists of a 10.4-megawatt diesel-fired power plant operated by Maui Electric Co. and a 1.5-megawatt privately owned solar facility. The high price of diesel is the main reason electricity on Lanai cost 44.2 cents a kilowatt hour in October, more than three times the national average.

Ellison hired UC San Diego’s Byron Washom in May to be the architect for Lanai’s energy transformation. The UC San Diego microgrid overseen by Washom enables the school to save about $850,000 a month on its electric bill because it is able to generate 92 percent of its own power.

The microgrid manages the campus’s 42-megawatt demand load using a mix of resources that includes two 13.5-megawatt gas-fired turbines, a 2.8-megawatt fuel cell powered by methane from a waste water treatment plant, 1.5 megawatts of solar and a 3-megawatt steam turbine. The facility stores energy using batteries, capacitors and thermal storage.

Washom declined to comment for this story, but the Pulama Lanai website includes a section that provides a broad description of the energy goals for the island.

"Renewable energy plays a huge role in a sustainable Lanai," according to the website. "The vision is for the entire island to be powered by multiple renewable energy technologies, which requires the creation of a micro grid that will enable all of the technologies to be orchestrated to work in harmony to provide reliable, affordable energy."

Microgrids don’t always have to have complex control systems like the one used by UC San Diego. A group of farmers in North Kohala, working with state and federal officials, recently installed a $1.8 million wind-powered pumping system to irrigate 400 acres of agricultural land across 14 different farms.

The project, which received about $1 million in federal and state funding, is capable of pumping about 30 million gallons of water a year. Maui-based Gen-C Energy Development LLC developed the project using a 100-kilowatt wind turbine coupled with a battery bank. The turbine maker, Northern Power Systems of Barre, Vt., specializes in such small-scale wind projects often in remote areas, a company spokeswoman said.