The following statement by the Hawaii Climate Commission highlights the critical role of forests in the mitigation of climate change: “Our forests have a huge role to play in reaching our net [carbon] neutral goal. Protecting existing forests as well as expanding their footprint will bring a suite of benefits including increasing soil health, recharging our water supply, providing resilient biodiversity, and protecting our reefs from erosion.”

Despite the importance of forests, two projects are seriously being considered that would use trees cut from forests to generate electricity in Hawaii. These projects are incentivized by a law that should be amended to discourage them.

Hawaii law requires that electric utilities transition away from using fossil fuels to generate electricity toward using renewable energy. The ultimate objective is 100% renewable energy by 2045.

The law is well-intentioned because it aims to reduce greenhouse gas emissions from Hawaii’s electric sector. It treats all biomass as renewable energy having no emissions. However, this accounting fails to recognize the difference in life-cycle emissions among sources of biomass, so the law treats the burning of trees identically to the burning of short rotation crops.

Even Hu Honua estimates that its proposed biomass project — one that would burn trees to generate electricity — will emit CO2 at twice the rate of existing fossil fuel plants it proposes to replace.

Commercial biomass for electricity generation is typically made by cutting down a forest to produce wood pellets. After the forest is cut, new trees are grown, and a new ecosystem is created.

It was once thought that this new ecosystem would take carbon out of the atmosphere immediately. However, recent research suggests that for approximately 20 years this new ecosystem actually generates more carbon than it sequesters. Thus, the land with the original forest goes from being a sequesterer of carbon to an emitter of carbon.

The deficit occurs because the roots of trees give off carbon, as does the decomposition of organic material by microbes in the soil. Although carbon is taken in by the leaves of the trees, that amount is less than the total amount emitted.

After about 20 years, when the forest reaches a certain maturity, it starts to take in more carbon than it emits. But 20 years is too long to wait because many climate scientists agree that we have only about 10 years in which to make the sweeping changes needed to ensure that the Earth remains livable for humans.

The Hawaii law that allows electric utility companies to burn all types of biomass, including trees, was passed more than 20 years ago when the push for renewables was primarily focused on wind and solar, without much attention paid to biomass. Since utilities are now pursuing biomass much more intently, the law should be amended in light of the climate emergency declared by the Hawaii Legislature.

If the law remains, the burning of wood pellets to generate electricity may be approved for the Hu Honua project on the Big Island and the AES project on Oahu. Environmentally, these projects would be setbacks.

Burning tree products to create electricity should be discouraged. Other types of biomass, however, such as crops with short growing cycles should be encouraged.

Renewable energy sources are readily available that are much less harmful to the environment than the burning of trees. Mature forests should be preserved — and even expanded — as a vital component of a strategy to mitigate climate change.

Hawaii is a national climate change leader. Let’s keep moving forward. Pass Senate Bill 2308.

Henry Curtis is executive director of Life of the Land; Dylan Ramos volunteers on a task force focused on the decarbonization of Hawaii’s energy sector.