Batteries and other energy storage systems are key to helping Hawaiian Electric Co. lower costs to consumers, experts said at a recent energy conference.
Several energy storage companies are working with HECO on new technologies aimed at helping to lower customers rates by 20 percent in the next 16 years, a goal listed in the utility’s proposal for Hawaii’s energy future submitted in August to the Public Utilities Commission.
Energy storage will play an important role as the utility works to upgrade the grid, said Darren Ishimura, acting manager of HECO’s Grid Technologies Department.
"Modernizing our grid is something we need to do," said Ishimura at the Asia Pacific Clean Energy Summit and Expo on Sept. 15 at the Hawai‘i Convention Center. "Energy storage is key to the transformation."
Energy storage will help Hawaii use more renewable energy, said Jeffrey Mikulina, executive director of the Blue Planet Foundation.
"Storage is really a game changer in our energy landscape in many ways," Mikulina said. "It can help use wind and solar when the wind is not blowing and the sun is not shining."
A battery is one of several kinds of energy storage that can support the grid and help maximize the use of energy created by renewable sources.
HECO divides energy storage in three ways, depending on the length of time it is stored.
The first form smooths energy coming from a renewable energy source by holding the energy for a fraction of a second before it enters the grid.
The second holds about a half-hour of power and is designed to be used if solar or wind energy generation drops off quickly because of clouds or low wind.
The third is the longest form of storage. These are batteries or other technologies that can collect power created by renewable sources and make the energy available during times of highest demand on the grid.
A battery can be installed to a meter at a residence, or a larger-scale battery can be connected to a utility’s electrical substation. Residential batteries, known as customer side of the meter batteries, sit next to the home’s solar system to collect energy to give back at a later time.
Energy storage reduces the need for more power plants and curbs strain on the grid’s technology. Storage can also make it possible to add more renewable energy sources and reduces costs to customers.
HECO said it is willing to work with different companies to create a grid that can accommodate renewable energy.
"We are open to a variety of different energy storage technologies on both sides of the meter to do the job we need, that is, let us add more renewables to the grid reliably," Peter Rosegg, HECO spokesman, said.
Millbrae, Calif.-based Stem Inc. makes energy storage systems that help cut the peak energy demand of commercial customers with a technology called "peak shaving."
Stem’s systems, a battery and a monitor, are connected to businesses’ meters. Powerscope, the company’s software, analyzes a business’s energy use and predicts periods of high energy demand. This software sends signals to the power monitor connected to the battery, automatically controlling when electricity is stored and when it is released.
"When we’re discharging the batteries, we are not disconnecting a whole building from the grid," said Tad Glauthier, vice president of Hawaii operations at Stem. "It’s not enough storage to take the whole facility off, but (it) is reducing the amount it is pulling, which has the effect on the grid like if a whole bunch of lights are turned off."
Stem’s battery helps reduce the cost for businesses by cutting the energy the companies demand from the utility at high periods. Unlike residential customers, HECO business customers pay more for peak energy use.
"We are working with Stem on this three-year demonstration because they have a technology for energy storage on the customer side of the meter," Rosegg said. "It can help customers manage their energy use and provide an opportunity for the utility to assess how customer-sited resources can help our system deal with more and more electricity from variable technologies like rooftop solar."
Stem’s battery can be used with renewable energy sources, such as solar, but it can also be used with a traditional energy setup.
"We don’t have to be (connected to PV). Our box is connected to the distribution panel inside the building. If there is solar coming in, those electrons could flow into the battery. If there is excess solar, that will flow into the battery. If there is no solar, that is fine, too."
Stem will be installing its technology at 25 to 35 locations in Hawaii within the next six months, said Glauthier.
"We have some very interested businesses that are typically ones with a sustainability mission — doing solar and have done other things — and this is something that they see is the next steppingstone," said Glauthier. "For this project we will focus some of the deployments on businesses that have solar specifically so we can look at those really localized benefits it can provide in terms of smoothing the output."
Depending on the outcome of the Stem project and others, HECO is looking to eventually expand energy storage systems to residents, Rosegg said.
"If the Stem project is as successful as we hope, and we can learn from it, we will look to expand to involve more possible providers and customers."
HECO’s August proposal named several energy storage companies it is working with, including Stem, People Power, Ibis Networks, Amber Kinetics, Ambri and Shifted Energy.
All of the startups are working with the Energy Excelerator, a company based in downtown Honolulu that provides funding, work space and networking to energy-focused startups. Stem received $1 million from Energy Excelerator to fund its projects.
"Energy storage is one tool in a portfolio that will be needed to help transition us to the electricity system of the future," Dawn Lippert, director of Energy Excelerator, said. "I think the key is building as much flexibility into the system as possible so that the electricity grid can accommodate cheaper, cleaner options as they become available."
