Okinawa power industry looks to reduce reliance on fossil fuels

The Yomiuri Shimbun
The Nakagusuku Biomass Power Plant is seen in mid-February in Uruma, Okinawa Prefecture.

The power industry in Okinawa Prefecture is now in a crucial transition phase as it looks to respond to the global trend toward decarbonization. Okinawa is facing the challenge of how to break away from its heavy dependence on thermal power generation and how to draw a path to the wider use of renewable energy.

On the main island of Okinawa stands a tall power generation facility. The Nakagusuku Biomass Power Plant stands in an industrial complex in the city of Uruma and has been operated by a Tokyo-based renewable energy company jointly with a subsidiary of Kyushu Electric Power Co., Okinawa Gas, among others, since July 2021. The output of the power plant is 49 megawatts and generates electricity for 110,000 households a year.

The power plant is fueled by imported palm kernel shells. Since the palm trees absorb carbon dioxide while growing, the plant is certified by the central government as a renewable energy facility.

Also in Uruma is Biomass Recycling Center, a company that produces biomass fuel using wood waste from the construction of area hotels and residences. The biomass fuel comes in the form of wood pellets and the company supplies them to thermal power plants run by Okinawa Electric Power Co.

After World War II, the United States administered Okinawa and built power generation facilities on Okinawa Island, establishing the Ryukyu Electric Power Corp. to operate them.

When Okinawa was returned to Japan in May 1972, Okinawa Electric was founded to take over from Ryukyu Electric Power.

Unlike other power companies in Japan, such as Tokyo Electric Power Co., which have been private companies since their establishment after World War II, Okinawa Electric was funded by the central government and prefectural government. It was initially a special public corporation to receive preferential tax treatment.

The reasons behind this move included concerns whether Okinawa Electric would be able to maintain stable operations because it depended too much on oil imports for thermal power generation. Geographic restrictions meant there were no nuclear power plants nor large-scale hydropower plants in Okinawa.

In 1973, the concerns became reality as the first oil shock hit. The second one came in 1979. Rising fuel prices caused Okinawa Electric to incur excessive debt. People were impacted as the price of electricity also jumped significantly.

Okinawa Electric then tried to diversify its power sources to avoid being affected by the global situation surrounding oil. Starting in 1986, the company started to purchase electricity from Electric Power Development Co., known as J-Power, which operates a coal-fired thermal power station in Uruma. Okinawa Electric also built coal-fired plants on its own. In 2012, it started operation of the Yoshinoura Thermal Power Plant, which mostly uses liquefied natural gas (LNG), in the village of Nakagusuku.

Even now in Okinawa Electric’s coverage area, about 90% of electricity comes from fossil fuels such as oil, coal and LNG. For the 10 major power companies across Japan including Okinawa Electric, the figure is about 70%.

The Okinawa prefectural government has taken action to address its region’s overdependence on fossil fuels. In March 2021, it compiled a clean energy initiative, a basic policy toward building a decarbonized society. The policy sets the goal of increasing the ratio of renewable energy in the energy mix to 18% by the end of March 2031. This ratio is more than twice as high as the current ratio.

“We aim to make sure that renewable energy will become the main power source,” said Okinawa Gov. Denny Tamaki at a press conference held when the initiative was compiled. He also announced that he would aim to promote the use of next-generation thermal power generation that does not emit CO2.

Okinawa Electric announced its target to reduce CO2 emissions to net zero by 2050 and a road map that includes an expansion of its renewable energy policy. The company is the first among the 10 major power firms to announce a net-zero target.

“We know it is difficult to realize decarbonization, but we would like to seek a balance with a stable supply of electricity by introducing new technologies,” said President Hiroyuki Motonaga.

Folding wind turbines

Courtesy of Okinawa Electric Power Co.
Wind power equipment on Hateruma Island in Okinawa Prefecture can be folded so it won’t be damaged in a typhoon.

To achieve decarbonization, efforts on Okinawa’s remote islands are also essential. The main power source on these islands comes mainly from internal combustion engine-based power plants that use oil.

On Hateruma Island, Japan’s southernmost inhabited island off the coast of Ishigaki Island, Okinawa Electric succeeded in covering the power consumption of about 500 residents for about 10 days in November 2020 using wind power and batteries to store the generated electricity.

Wind turbines installed on the island can be lowered in case of typhoons or other weather in which the wind is unsuitable for power generation. This system is the first such facility in Japan where such storm damage can be prevented. While the scale is small, there is anticipation these turbines can be used effectively.

“As Okinawa has remote islands, power plants are dispersed, making it difficult to achieve large-scale, high-efficiency power generation,” said Junichiro Tsutsumi, a professor emeritus at the University of the Ryukyus. “Considering typhoons, solar power and wind power generation will not be easy to maintain.”

The specialist on energy issues in Okinawa added: “For decarbonization, it is necessary to carefully examine an energy mix most suitable to regional characteristics. The challenge should be tackled through a long-term perspective in cooperation with industry, government and academia.”