Study Says Influx of Dead Trees Can Be Handled Through Co-Burning

Researchers at the University of Wyoming say a vast number of trees killed by a bark beetle population that is rapidly expanding due to higher temperatures could be sustainably co-fired in coal plants.

It’s an important finding, especially as Congress undertakes conference committee work on House and Senate versions of energy legislation that includes in the Senate version a provision that deems biomass “carbon neutral.”

The language in the Senate provision would recognize that sustainably produced and managed biomass can offer valuable clean energy contributions and important carbon sequestration services to mitigate climate change. Currently 13 different definitions of biomass exist in various laws and regulations, and the bill’s sponsors hope that they can all be harmonized in a way that allows for the full potential for bioenergy solutions to be realized.

Erica Belmont and Emily Beagle, professors of mechanical engineering at the University of Wyoming, say in their report, which was published by the journal Science Direct, the “widespread mortality of forests in the western United States due to a bark beetle epidemic provides a source of biomass for power generation.”

The researchers assessed the availability and economics of co-firing beetle-kill biomass with coal in power plants in the western United States and concluded that “[s]ince biomass may be considered carbon neutral under careful management, co-combustion of biomass with coal provides power plants a way to meet emission reduction requirements, such as those in the EPA Clean Power Plan (CPP).”

They note that cost has been a barrier to co-firing, “but the economics are altered by emission reduction requirements,” such as the guidelines proposed under the Clean Power Plan, which is currently on hold pending resolution of a lawsuit, probably later next year.

Furthermore, they say co-firing reduces the need for the U.S. Forest Service (USFS) to manage beetle-kill trees, noting the mitigated treatment costs from the reduced risk of wildfire were considered as an effective subsidy of co-firing. In fact, they say policymakers should look at the “novel” approach of using USFS funding to subsidize co-firing, given the burning of beetle-kill biomass is “among the most economical ways to meet emission reduction requirements.”

In June, California’s Department of Forestry and Fire Protection, citing USFS aerial surveys, said there were more than 66 million dead trees across the state (up from 29 million in 2015), killed by drought and bark beetles since 2010 and prompting “continued concern for California’s forest health and wildfire danger.”

The California estimate shows the voraciousness with which the tree mortality epidemic is gripping the region, killing trees in numbers hard to imagine. But open-pile burning in the forest – the most commonly used method of disposing of woody biomass waste – is hardly an option, given the emissions of air pollutants, greenhouse gases (GHGs) and air toxics open burning produces.

While there will always be questions over the costs of transporting dead trees to power plants, the Wyoming researchers make the case that given the tough regulations aimed at reducing climate emissions that coal-fired plants are facing, obtaining and co-burning the biomass might be the more economical alternative.

They also point out that disposing of the biomass will release emissions anyway, so it could be better used by co-firing it in coal plants and helping to offset some of the heavier emissions that come from burning coal. And though only a small fraction in number when compared to coal-fired plants, biomass-only generating plants could also use the dead trees as fuel.

Another study published in July by researchers with the USFS, a number of California universities and others seems to underscore the Wyoming findings, by discussing the use of forest wastes from fuel hazard reduction projects as a means of electricity production. It makes the case for policies that monetize the reductions in emissions as a way of making the use of dead trees for energy production more economically viable. The state legislature ultimately passed a bill that would allow dead trees to be used as a power feedstock.

It’s an approach that policy makers intent on addressing climate change should consider. Start by harmonizing the legal and regulatory definitions of biomass to ensure that properly managed forests – both private and public – can make meaningful and significant contributions to our nation’s energy strategy, while also reducing the considerable hardships and risks associated with forest fires. Let’s not hinder our access to cleaner and more sustainable resources that can power this nation forward.

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