When it comes to biomass – and, specifically, the burning of scrap lumber and forest debris (and even that term “scrap” is debatable) – people on both sides of the debate agree that not only do trees release carbon dioxide when burned, but they are also the most effective tool we have at removing CO₂ from the atmosphere.
The question and disagreement, then, is what the net result is: do trees – the source of biomass for energy – capture the same amount of CO₂ (through photosynthesis) while growing?
It’s a political, economic and environmental conundrum, for according to the U.S. Energy Information Administration, in 2019, biomass provided nearly 5 quadrillion British thermal units and about 5 percent of total primary energy use in the United States.
The European Union is regarded as a model for the rest of the world for its reliance on renewable energy, which accounted for 38 percent of its electricity generation in 2020, according to a study released early this year by U.K. think tank Ember and German think tank Agora Energiewende.
“Almost half of the ‘renewable’ energy that Western Europe credits itself for is biomass of various kinds,” said Scott Tinker, director of the Bureau of Economic Geology at the University of Texas at Austin.
To industry and its proponents, biomass is a carbon-neutral energy source. Environmentalists, however, point to the deforestations, pollution and water use and see potential calamity.
‘A Low-Carbon Alternative’
“Displace Coal. Grow More Trees. Fight Climate Change.” This is the slogan emblazoned atop the homepage of Enviva, the world’s largest producer of industrial wood pellets, which are offered as “a low-carbon alternative to fossil fuels.”
On its website, the North Carolina-based Enviva claims its corporate philosophy is “to improve the environmental impact of energy generation by helping to replace fossil fuels with sustainable wood bioenergy” while “maintaining and improving the health of our forests while reducing greenhouse gas emissions on a lifecycle basis around the world.”
One way Enviva does that, it states, is by requiring landowners who supply its wood to replant their forests. The company uses GPS technology to track and trace every harvest to see if their suppliers comply. Further, it has also committed to help protect 35,000 acres of threatened bottomland hardwood forests, deciduous and evergreens, and restore 5,000 acres of natural longleaf pine. To put this in perspective, according to the Nature Conservancy, there are 4 million acres of such forests in the region.
As to what kind of wood is being made into pellets for energy, the debate, too, is pretty strong, for even those trees not wanted for timber – so called “waste” or “low value” wood – which the industry maintains is its harvesting priority, provide habitat for migratory birds, as well as carbon storage.
Efforts to reach representatives from Enviva were unsuccessful.
Defining ‘Clean Energy’
Tinker said calling biomass a “green” energy is at best a linguistic stretch.
“Biomass and biofuels are carbohydrates; carbon-based fuels,” he said, “and the concept of it being environmentally friendly stems from the simplified idea that since plants take up CO₂ when growing, while releasing CO₂, while burning, the process is hypothetically carbon-neutral.”
What this does not account for, he maintains, is everything required to harvest, transport, process, ship internationally (where applicable) and then transport to the biomass power plant. Taking all that into account, Tinker calls the process “hardly carbon neutral,” even when one stipulates to the carbon-capture potential of trees.
“It takes years to decades to grow the plants and trees, and hours to burn them,” he said.
And he wonders if we’ll soon run out of land to feed the fuel furnace.
Digging deeper into the terminology, Tinker said he understands how and why the term is used.
“If ‘clean’ is only CO₂ emissions, burning biomass may be better than burning coal,” he said.
And that is because coal does not get credit for present-day atmospheric CO₂ removal. If the full effect of biomass were considered, the story, and equation, would be different.
“If we expand our definition of ‘clean’ to include the soil and water, biomass and biofuels do not fare so well,” said Tinker.
And that expansion of definition includes forest removal, the development of fast-growing plants, fertilization and the impact of irrigation and runoff.
“All have environmental impacts. And the loss of permanent forest to develop fast-growing agriculture is also an environmental challenge,” he said.
Is the ‘Cure’ Worse than the Disease?
Tinker believes that the environmental benefits of biomass are exaggerated, especially considering that gathering deadfall from forest floors takes as much energy in transportation fuels to gather, move the material and refine it into useful products, as it eventually provides. He said, for example, if low-density plants need to be transported more than 50 miles or so from where they are grown to the conversion facility (refinery), the trucks that haul them will burn more fuel – diesel or biodiesel – than the load being hauled will produce.
He does see the appeal of biomass in certain situations, however.
“That said, forest management policies that clean up deadfall, and allow for controlled burns, can help prevent uncontrollable forest fires, as we have seen in California,” he said.
Tinker, whose two films, “Switch” and “Switch On,” focus on the sources and uses of energy presently and the challenges and choices ahead, especially for those in the developing world, sees biomass as an answer to the world’s future energy needs, but nothing close to the answer.
“Biomass is a very low-density form of energy, like geothermal, hydropower, solar, wind and batteries. To provide affordable, reliable energy to 7.7 billion people, many of whom are just beginning to emerge and develop economically, will require very dense forms of energy, like oil, natural gas, hydrogen and nuclear (uranium and thorium),” he said.
On the making of the pellets, Tinker said, “That process takes energy. Nature – time and pressure – already did that with coal and oil.”
Pellets and Policy
Politically, the news from the Biden administration has both sides of the debate in a holding pattern. The administration’s Agriculture Secretary Tom Vilsack is a strong supporter of biomass power, while the administration’s new EPA Director Michael Regan seems less convinced. Largely supported by environmentalists for his efforts at regulation and winning self-settlement against coal ash polluters while he was the head of North Carolina’s Department of Environmental Quality, Regan disappointed many by approving every request Enviva made to increase its operations.
Under the Trump administration, its EPA agreed with proponents in the biomass industry and ruled that wood pellets are a carbon-neutral form of energy.
Others disagreed – and put the landscape, if you will, in starker terms.
In February, more than 500 scientists and economists wrote to a number of world leaders, including President Joe Biden, stating, “The burning of wood will increase warming for decades to centuries. That is true even when the wood replaces coal, oil or natural gas,” adding, “trees are more valuable alive than dead both for climate and for biodiversity.”