Hawaiian Electric Co. wants to combine the annual greenhouse emissions caps for 13 power plants in Hawaii, a move some believe would allow Hawaii’s lone coal-fired power plant to increase greenhouse gas emissions.

HECO has submitted an application for a permit to combine the facilities’ GHG emissions caps to the state Department of Health, which would allow facilities a higher cap if others fall below their individual limits.

The AES Hawaii coal-fired plant in Kapolei could use whatever is left of the GHG emissions caps of the other plants. AES Hawaii is the single largest power generator in the state, but also one of the dirtiest.

According to 2017 data from the Environmental Protection Agency, AES Hawaii reported emitting 1,470,000 metric tons of CO2e, or “carbon dioxide equivalent,” trailing only HECO’s Kahe Generating Station, which released over two million metric tons in 2017.

The permit would allow the 13 plants altogether to release up to about 6.4 million metric tons of CO2e per year. Currently, AES Hawaii is capped at about 1.5 million metric tons.

The Sierra Club’s Hawaii chapter is calling for the public to testify against the application during a DOH meeting at 6:30 p.m. today at the Momilani Elementary School cafeteria.

“We’re dedicated to ensuring that Hawaii’s coal-free by 2023,” said Lauren Watanabe, Sierra Club’s Oahu program manager.

In 2007, Hawaii made into law a pledge to reduce statewide GHG emissions to 1990 levels by January 2020. Also starting in January is a GHG emissions reduction plan in which high GHG-emitting facilities will have caps that are 16% below their individual levels from 2010.

In its application, HECO said combining the emissions cap would help provide protections in case another “facility has unplanned outages or there is reduced output from renewable generation such as solar.”

If a renewable energy source were to experience a loss in production, a combined cap would allow nonrenewable plants to pick up the slack with fewer worries about reaching individual emissions caps.

“Our application to DOH is to establish an emissions reduction ‘partnership’ with some independent power producers, including the AES Hawaii plant, so collectively we achieve the 16% reduction,” said HECO spokesman Peter Rosegg. “This partnership would allow AES, which will close in 2022, to operate while avoiding higher energy costs for our customers.”