Maui Electric Co. produced 35.4 percent of its power from renewable energy in 2015, up slightly from the previous year but the second highest percentage in the state behind the Big Island’s 48.7 percent, according to the state Energy Office in its annual Hawaii report.

Shayna Decker, director of communications for MECO, broke those totals down further — 23.2 percent from the Kaheawa and Auwahi wind farms, 8.5 percent from solar, 2.7 percent from biomass or bagasse at Hawaiian Commercial & Sugar Co. and 1 percent biofuel.

MECO is expecting its 2016 renewable energy portfolio standards to be similar to 2015’s and not to dip despite the closure of HC&S in December, Decker said. She noted that the last sugar plantation in the state already had been providing less power following a revised power purchase agreement in October 2015.

“As a result, we expect the impact to our renewable energy percentage without HC&S to be minimal,” she said.

The 2017 renewables percentage should reflect two large-scale solar projects, expected to go online midyear, said Decker. However, the South Maui Renewable Resources 2.87-megawatt solar farm, located on 12 acres above the Maui Research & Technology Park in Kihei, and the Kuia Solar 2.87-MW farm on 12 acres near Lahainaluna High School, are only expected to bump up the renewable percentage by less than 1 percent.

Efforts to reach officials with the solar projects for a progress report have been unsuccessful.

“As the energy report confirms, we continue to make progress as we work together in our state’s clean energy transformation,” said Decker. “Going forward in 2017, we recently proposed solid energy plans that show we can do this. It will take work with parties from all segments of our community — government, business, community and environmental groups — to refine the plans for Hawaii’s energy future.”

The Energy Office, part of the state Department of Business, Economic Development and Tourism, released its “2016 Energy Resources Coordinator’s Annual Report” in late December. It highlights the policies and activities that have advanced the state about a quarter of the way toward its target of achieving 100 percent renewable energy by 2045.

The state’s renewable energy portfolio standard percentage for 2015 was 23.4 percent, the report showed.

In gleaning Maui County data from the 86-page report, there was a bar graph showing Maui’s renewable energy potential, with the greatest potential for geothermal energy. The island had a 1,170-gigawatt-hour geothermal power production potential, according to the report. Only the Big Island, which already produces geothermal power, and Maui were considered options for geothermal energy.

Decker said that studies have indicated that Maui has geothermal energy potential, which could be valuable as a firm source of power, unlike wind or solar, which are intermittent depending on the weather.

“However, more discussions are needed to evaluate this as a possible future resource,” she said.

The report also cited a 700-GWh potential for wind power, 340 GWh for solar power, 230 GWh for biomass, 30 GWh for ocean power and 10 GWh for hydropower.

For Lanai and Molokai, the report showed 700 GWh of potential power from wind and 4 GWh from solar. Residents on both islands have battled developers seeking to build wind farms on their islands.

“We’ll soon be asking the Public Utilities Commission to be able to start the process to seek more renewable energy projects in Maui County through a competitive process to ensure the best value for our customers,” Decker said.

On the electric vehicle front, Maui was far ahead of the other Neighbor Islands, the report showed. In July, the number of registered EVs on Maui was 721, more than Hawaii island’s 207 and Kauai’s 157 combined. Oahu had 3,451 registered EVs.

Maui also had 121 EV charging ports — 80 level 2 and 41 fast charging, according to the report.

The report gave a lot of credit to the $55 million JUMPSmart Maui project, an international partnership among Japan, Hawaii and Maui. It aims to improve the integration of renewable energy resources into Maui’s electrical grid and to prepare for adoption of electric vehicles.

Molokai has faced issues with power outages and a saturated rooftop solar environment. The report mentioned a Clinton Global Initiative commitment, where the state Energy Office and MECO partnered to plan for reaching the 100 percent renewable goal for the Friendly Island in 2030, 15 years before the state mandate.

Decker said that, in energy plans submitted to the PUC in December, the utility proposed a mix of solar, wind, battery storage and biofuels to achieve the renewable portfolio standard of 100 percent on Molokai by 2030.

As part of these plans, the report referred to a grid-scale energy storage system that MECO is working on in partnership with the Hawaii Natural Energy Institute, Decker said. Commissioned in July, the demonstration project will evaluate a fast-response system where energy could be instantaneously provided to the grid when needed.

The institute obtained the battery storage system for $1.85 million with MECO contributing $1.45 million for the project, she said.

As for increasing rooftop solar, MECO is partnering with E-Gear on a pilot program to potentially allow more customers to interconnect PV systems on Molokai. The level of PV systems already installed or approved for installation on the island’s small electric grid is among the highest in the state, Decker said.

“As a result, new PV applications on Molokai have experienced delays as solutions are sought to address reliability and safety issues,” she said.

The pilot program by the renewable energy innovation company will include installation of specialized energy management control and storage technology, which will allow the utility to monitor and control energy flow, Decker explained.

One of the problems with rooftop solar is that power flow is uneven due to the weather and the radiance of the sun. The problem for the utility is that it has to match production of power with demand at every moment. Most rooftops solar systems already installed flow power into the grid unregulated.

The technology could potentially improve the interaction of rooftop PV systems with the grid and reduce the chance the systems “will undermine reliable service and power quality,” said Decker.

Ten customers will participate in the pilot program, she said. MECO will evaluate the performance of the systems to determine whether similar systems can be used to integrate more solar power in areas with high concentrations of rooftop PV systems.

* Lee Imada can be reached at leeimada@mauinews.com.