Biomass energy has been drawing increasing scrutiny in recent years.
Kevin Bundy has tramped through his share of forests in California’s Sierra Nevada. Where he sees a diverse ecosystem of ponderosa pine, incense cedar, and white fir, prime wildlife habitats, and one of the world’s best buffers against climate change, many public and private land managers see something different. Of course, they too observe living forests, but they also see tinder for future wildfires, as well as an opportunity to procure home-grown, renewable biomass energy.
photo by Oregon Department of Forestry
A senior attorney with the conservation group Center for Biological Diversity, Bundy works at the national level to ensure strict accounting of carbon emissions from the burning of biomass, and on the local level to limit the type of fuels burned by biomass facilities. He’s convinced that the nation needs to “get away from fossil fuels and shift to 100 percent renewable energy as quickly as possible,” given the threat of climate change. But while he acknowledges biomass might be renewable “in some sense,” he sees it as “something of a false solution to our climate and energy challenges” compared to other renewable sources like solar and wind.
Yet biomass is big business in the United States. In 2014, half of “renewable” energy in the US came from bioenergy – that is, from burning trees, crop residues (most often from corn and soybean harvests), manure, and even trash to produce electricity and heat, or to manufacture liquid transportation fuels like ethanol or biodiesel. Meanwhile, hydropower accounted for 26 percent, wind made up 18 percent, and solar accounted for a mere 4.4 percent. A significant increase in biomass energy production is likely as the US tries to ramp up its renewables output.
There remains considerable debate about just how prominently biomass should feature in energy planning, what with disagreements about the impact it has on forests and agricultural land, how clean it is, and its contributions to climate change. Much of the public is also confused about how biomass compares to other forms of renewable energy. This confusion reflects the conflicting scientific opinions and government policies regarding biomass energy.
Biomass fuels can include a wide variety of materials, and researchers are continuing to discover new bioenergy sources. However, one specific kind of fuel, woody biomass, has been attracting the most attention – and conflict – in the US.
There are four primary components to woody biomass: manufacturing residues like woodchips, sawdust, and bark from lumber milling operations; post-consumer waste, such as leftovers from construction and demolition; urban and agricultural wood waste from tree trimming; and logging operations. The lion’s share of biomass fuel falls into this fourth category. This can include treetops and branches, as well as whole trees, typically those that are too small, crooked, knotty, or rotten to turn into lumber.
The majority of woody biomass power is generated from selective logging and the byproducts of logging for lumber and other forest products. But another increasingly common source of woody biomass is from US Forest Service “fuel reduction” or “restoration” projects on public lands, aimed at preventing wildfires.
Currently, the Forest Service estimates that 65 to 82 million acres of public lands have become overgrown with young trees following past logging, grazing, and fire suppression efforts, and are in need once again of “restoration” to minimize fire risk. The biomass industry agrees, advocating for an uptick in fuel reduction logging, with the byproducts going to fuel biomass facilities.
These “fuel reduction” logging programs are a sticking point for many environmental groups, who see excessive logging as harmful to forest lands, and fuel reduction policies as largely ineffectual and unnecessary.
The Center for Biological Diversity, for one, has stopped short of denouncing all bioenergy, but has argued that the economics of biomass energy often require ecologically damaging logging policies. Biomass industry growth, the organization worries, could lead to additional logging, to the detriment of forests, wildlife, and watersheds.
The US has roughly 200 woody biomass power facilities that generate only about 11 percent of the country’s biomass energy. Because of their large scale and limited efficiency (roughly 75 percent of heat energy is lost during electricity generation), these facilities can, by some estimates, require access to thousands of acres of forestland per year, which many conservationists see as a threat to ecosystem protection.
“Bioenergy is bad for forests, fish and wildlife, and biodiversity,” says Jim Ace, healthy forest campaigner for Stand (formerly ForestEthics), an environmental group that works to protect forests and promote a stable climate. “New wood-burning power plants will increase already high deforestation rates.”
Not everyone agrees. Brent Bailey, state activities coordinator for the 25x’25 Alliance, a national coalition led, advised, and endorsed by the bioenergy, agriculture, and forest products industries, doesn’t think logging is a problem. He considers biomass energy a forest-friendly alternative to fossil fuels, the expansion of which is crucial to achieving 25x’25’s goal of getting 25 percent of energy in the US from renewable sources by 2025. He says the nation has an “abundant supply of biomass resources and the untapped potential to significantly increase biomass growth.”
Another, perhaps greater, question surrounding biomass energy is how it contributes to global climate change, and specifically, how to account for biomass carbon emissions. Long considered a better option for the climate than fossil fuels, biomass-related emissions have come under increased scrutiny over the last several years.
The climate issue hinges on the interplay between biomass energy emissions and carbon sequestration. In the case of wood-burning power plants, the biomass comes from trees, which capture or sequester carbon when standing. Cutting and burning trees and plants for bioenergy releases that carbon. So the question becomes, if forests are continually regenerating, is all that emitted carbon eventually resequestered? And if so, over what time frame?
The answers can be complicated.
Some biomass advocates assert carbon dioxide emitted from biomass combustion must be distinguished from what’s released from burning fossil fuels. “The CO2 released when biomass is combusted has, by definition, always been previously removed from the atmosphere via photosynthesis,” says Bailey. “Our view is that the use of plants, crops, and trees for energy and bioproducts operate within the natural carbon cycle in a way that, unlike fossil fuels, does not add new sources of carbon to the atmosphere.”
In November 2014, the National Association of University Forest Resources Programs sent a letter to the US Environmental Protection Agency expressing a similar stance. Signed by 100 scientists and professors, the letter outlined the “long-term benefits of forest biomass energy” given forest regrowth.
This concept of “biogenic” carbon emissions – those related to the burning of biologically based materials – has been challenged by a number of other scientists who say that whether the emissions come from coal or fir trees, it’s all the same to the atmosphere. It’s the total concentration of greenhouse gases being released that is of concern. A 2012 study published in Global Change Biology Bioenergy found that the most likely result of a surge in logging for bioenergy is a “permanent increase in atmospheric CO2 concentration.”
Then there is the matter of the time frame for carbon emissions calculations. Generally speaking, most experts agree that in the near-term, logging and burning of whole trees for biomass will lead to an increase in carbon emissions. After all, trees don’t regrow overnight. Over the long term, however, some scientists believe carbon emissions may be counterbalanced by forest regeneration, leading them to urge carbon accounting take place over a 100-year time frame.
But as CBD’s Bundy warns, we must cut our carbon emissions now to avoid catastrophic warming. In that context, a 100-year time frame makes little sense.
Other environmentalists put it more strongly. “Biomass incineration is fundamentally different from other renewables in that it necessarily keeps polluting for each megawatt-hour it produces,” says Mike Ewall, co-director of Energy Justice Network, a Philadelphia-based organization focused on the environmental and public health impacts of various energy sources. Ewall insists there isn’t time to “play games with bogus carbon accounting, pretending that burning wood or other ‘biomass’ is a climate solution.”
This divergence of opinion on how to account for biomass emissions is reflected in US policy. President Obama’s climate regulation, the Clean Power Plan, promotes at least some forms of biomass energy as a boon for the climate. Yet the EPA, which is largely responsible for implementing the plan, has spent the last seven years mulling over how to account for biomass carbon emissions. The agency’s 2014 draft framework for biomass emissions accounting acknowledges that “carbon neutrality is not an appropriate a priori assumption” when it comes to biomass emissions. Instead, “it is a conclusion that should be reached only after considering a particular feedstock’s production and consumption cycle.”
Yet in late 2014, Janet McCabe, acting assistant administrator for the EPA’s Office of Air and Radiation, issued a memo stating that the agency intended “to propose exempting biogenic CO2 emissions” produced from logging forests for bioenergy if the trees are cut from “sustainably managed lands.” And this spring, seemingly impatient with the EPA’s slow pace on the matter, both the House and Senate passed the Energy Policy Modernization Act. The Senate version contains an amendment that would classify forest biomass energy as carbon neutral. The two versions of the bill are now being reconciled in Congress.
Clearly there is a wide spectrum of views on biomass energy. Some think it has a huge role to play in the clean energy sector, others believe it might make a modest contribution, and yet others simply won’t excuse its impact on forests and the climate.
There’s one other stance, best labeled as “power down.” Folks pushing for this don’t wade much into the biomass debate. Instead, they see any attempt to switch from fossil fuels to renewables without a reduction in energy consumption as nothing more than a distraction.
Josh Schlossberg is a Denver, Colorado-based freelance journalist and editor of The Biomass Monitor, the nation’s leading publication investigating the whole story on bioenergy, biomass, and biofuels.