Biomass Electric Power Generation Dirtier than Coal? Not Possible

As an Adjunct professor teaching two unique interdisciplinary courses on sustainable energy at The George Washington University, I read the article that biomass power plants are more polluting than coal with incredulity. Not only is the report incorrectly covered on it’s major three points, but it leaves out three other important points that readers need to know. And a recent modeling study on biofuels carbon balance is also lost in the weeds.

In John Upton’s Grist article, he reports “more than 70 wood-burning plants are under construction or have been built in the U.S. since 2005, with 75 more planned, according to the analysis by the nonprofit Partnership for Public Integrity…For every megawatt-hour of electricity produced, even the “cleanest” of the American biomass plants pump out nearly 50 percent more carbon dioxide than coal-burning plants…”

And then Climate Wire reported on a recent University of Nebraska study: “Last week, University of Nebraska, Lincoln, researchers published a paper in Nature Climate Change finding that fuels made from corn residue — the tough, fibrous stalks, corncobs and leaves left atop fields after harvest — could remove carbon from the soil, leading to a net increase of greenhouse gas emissions compared with conventional gasoline over a five-year cycle.”  

One of the largest U.S. corn stover biofuels producers, POET-DSM, is asking farmers to harvest only 1 ton of corn residue per acre — about 25 percent of the available material — according to the company’s website. According to Karlen’s calculations of the figures in the Nature Climate Change study, the researchers assume a 75 percent collection rate.  Ya know, if you model three times what the actual rate is, sure the carbon balance will be off.  But stover is great fertilizer and way less expensive than fossil-based fertilizers, so no way farmers will sell all their stover and replace it with higher cost fertilizers. And that’s the point with computer models, unless you interface with the “actors in the field” you will wind up with manure and not good science.

And now, the PPI study not only is wrong on all it’s major points, it’s not even looking at the other emissions of coal-produced electricity and confuses biomass generation with garbage incineration. The sophmoric study would get an “F” in my class. Here’s why:

First and foremost they lump every kind of biomass power generation together and then they confuse mixed waste as biomass in the study. Landfill gas and biogas from manures, sewage, and municipal water systems were left out – and they are the most environmentally beneficial renewable energy generation plants offsetting methane, a potent greenhouse gas and preserving water quality. If you take out municipal solid waste, then of the eight biomass waste streams, they were focusing on only wood.

Supposed Fact One: “For every megawatt-hour of electricity produced, even the “cleanest” of the American biomass plants pump out nearly 50 percent more carbon dioxide than coal-burning plants, PFPI staff researcher Mary Booth, a former Environmental Working Group scientist, concluded after poring over data associated with 88 air emissions permits. The biomass plants also produce more than twice as much nitrogen oxide, soot, carbon monoxide, and volatile organic matter as coal plants.”


The simple picture from 2006 EPA:

Comparing Uncontrolled Emissions from Different Fuel Sources

Supposed Fact Two: “The problem is rooted in lax regulations for an industry that’s widely mistaken to be clean. EPA rules allow biomass-burning plants to produce more than twice as much pollution as coal plants. Because of this perfect storm of lax regulation and regulatory rollbacks, biomass power plants marketed as ‘clean’ to host communities are increasingly likely to emit toxic compounds like dioxins; heavy metals including lead, arsenic, and mercury; and even emerging contaminants, like phthalates, which are found in the ‘waste-derived’ fuel products that are being approved under new EPA rules. …”


According to biomass expert Bill Carlson: “Perhaps one third of the total PPI document is devoted to Hazardous Air Pollutants (HAP) emissions from biomass and the lack of regulation, control and documentation. In reality, if lead or mercury or chlorine is not present in fuel in the first place, it is not going to be present in emissions. EPA and state regulators appreciate and accept this fact, but the authors clearly do not understand it. Much is made of dioxin and HCL in the report, but virgin wood does not contain more than trace amounts of chlorine, a necessary element in in both pollutants. The vast majority of biomass fuel in the United States remains residue and waste material from the agriculture and forest products industries, and that is not expected to change. These materials do not contain the precursors for the HAPs of greatest concern. And,  if the wood fuel contains no mercury to begin with, it is not going to be formed in the combustion process.”

The paper states that biomass power seeks to avoid more stringent EPA emission limits and instead finds a way to rely on more lenient state standards. In fact, the relationship was designed such that the EPA limits are a minimum, and can be exceeded by the states, but never made less stringent. The Clean Air Act was designed so that states could get “delegated authority” from EPA to run the air quality permitting program so long as they ran it in accordance with an EPA approved State Implementation Plan — a system that has been in place for more than 40 years and works just fine.


Omission One: Methane 

When biomass degrades, it turns to methane. According to the EPA website, methane is 21 times more potent than carbon dioxide. According to the U.S. Environmental Protection Agency (EPA), “Over the past 30 years, an average of143.3 million tons of wood-based products was produced annually in the United States (Howard 2012). The manufacture of these products generated about 84 million tons of wood residue (about 40 percent fine residue, including sawdust, and about 60 percent coarse residues), with more than 98 percent used by the wood products industries for fuel, pulpwood and feedstock for products such as particleboard (Smithandothers2009,Table 1). Note: I am not including in this treated wood residue, atremendous amount of wood ends up in the North American municipal and construction and demolition (C&D) waste streams, which should be treated differently.

According to waste characterization data from the US. Environmental Protection Agency (EPA) and Natural Resources Canada (NRCan), the Forest Products Laboratory estimates that wood makes up over 10 percent of all waste generated in North America (USEPA2009,NRCan2006). And note, that wood that cannot be naturally absorbed into the forest floor, causes forest fires.

So leaving wood and untreated wood waste to biodegrades to methane is a major greenhouse gas problem. Methane’s lifetime in the atmosphere is much shorter than carbon dioxide…Pound for pound, the comparative impact of CH4 on climate change is over 20 times that of carbon — it is a climate change accelerator gas.

Omission Two: Carcinogens (Cancer Causers) 

Trees and burning trees or wood does not cause cancer.

Cacinogens from coal and the polynuclear aromatics from coal combustion: This point is of importance, particularly since the inhalation of PNA in situations of air pollution. Soot is not a homogenous substance and several factors determine its properties. Soots will lose some of the absorbed chemicals during their residence in air, but they retain their PNAs for long periods of time when they reach the soil. The carcinogenicity of PNAs in the adsorbed state may be completely absent, depending on particle size of the soot and availability of eluting capability of the tissues or cells in contact with the soot. Whenever the carcinogenic polynuclear aromatics can be eluted they will be active in producing cancer if their residence is adequate. (Health effects of coal mining and combustion: carcinogens.)

Omission Three: Hormone Disruptors and Immune Suppressors 

Trees do not have lead or mercury.

Immune suppressors and hormone disruptors can cause: brain damage, lowered IQ, hearing loss, miscarriage, premature birth, increased blood pressure, kidney damage and nervous system problems. Aside from mercury, coal has a range of toxic elements including heavy metals that are all hormone disrupters and immune suppressors including lead, mercury, nickel, tin, cadmium, antimony, and arsenic, as well as radio isotopes of thorium and strontium.  Few people realize that lead may disrupt hormones. Heavy metals may also play a role in diabetes, since mercury has been shown to damage cells in the pancreas that produce insulin, which is critical for the body’s ability to metabolize sugar. Now the EPA Mercury Rule will lower mercury from new coal plants but not eliminate mercury in our air and water, or the host of other heavy metals. Wood, manures, and waste crop do not contain significant amounts of heavy metals found in coal. 

Omission Four: The Most Egregious — Science and Economics

The report states, “It’s sometimes argued that biomass fuel helps the climate, because the trees suck up carbon dioxide as they grow, offsetting the emissions that are released when the fuel is burned. But the report notes that it can take decades for forests to suck up the carbon dioxide that’s released when they are incinerated — and that “carbon offsets are never actually required to be obtained or demonstrated by these plants.”

Excuse me? “It’s sometimes argued?”  In fact virtually every major climate and environmental think tank and international studies have favorably addressed the cycle of growing trees (younger growing trees absorb the most carbon) and utilize the trees for energy and bio-products.   

Well sorry, almost every biomass study shows solid and positive carbon balances regarding woody biomass and manures. Just a sampling.

In the report Forest Sustainability and Carbon Balance of EU and North American Forest Biomass for Bioenergy Production (September 2013), “In the SE U.S. — a region which private landowners own 84 percent of total forest land, and over 93 percent of forest growing stock — net forest growth exceeds removals by 35 percent, and standing biomass volumes are higher than at any point in the half century despite the fact that over the ame time frame harvest volumes have doubled.”

In Oak Ridge National Lab study, Biomass Fuels, Energy, Carbon and Global Climate Change, by Janet Cushman, Gregg Marland, and Bernhard Schlamadinger, “Forests that are not harvested do not continue to accumulate carbon indefinitely. They eventually approach maturity and achieve, over time, a balance between the carbon taken up in photosynthesis and the carbon released back to the atmosphere from respiration, oxidation of dead organic matter, and fires and pests”

“Using current technologies, the most efficient way to convert biomass to useful energy, and thus to maximize the carbon dioxide savings, is to burn the biomass for heat or electricity generation, displacing coal. In all scenarios, carbon dioxide benefits increase as biomass growth rates increase and as utilization efficiency increases. The Biofuels Feedstock Development Program at ORNL aims to increase the productivity of tree and grass crops and improve the efficiency of biomass feedstock supply systems. Improvements in these areas offer a large payback both in the economics of biomass fuels and in the potential for net reductions in carbon dioxide emissions.”

And in the International Energy Agency Greenhouse Gas Balances of Biomass and BioEnergy Systems they create a standard methodology for calculating greenhouse gas balances with biomass and biomass energy. In subsequent studies they show that biomass energy has positive net carbon balances.


The bottom line, for greenhouse gas reduction, the world needs to plant far more biomass so it can sequester greater amounts of carbon. Growing biomass dies, drops slash and leaves, and gets knocked over by storms and floods.  To mitigate methane that would be released and to address the lack of carbon sequestration by older biomass, there needs to be a cycle of utilization of this biomass, so newer biomass can be planted so carbon sequestration can be maximized. And the energy produced can offset more carbon-intense electric generation from coal and heavy oils.

The PPI study is wrong on many points, confuses resources, leaves out biogas, biodiesel and contaminated crop biomass resources, ignores the other emissions from coal and coal ash, and does not consider the carbon benefits of replanting sustainable biomass while cycling out older and waste biomass — which makes serious discussion difficult.

Can we increase the positive carbon balances in biomass, enhance sustainable biomass without fossil (and high carbon inputs). Yes. But we need serious analysis, policies, and incentives for this critical renewable resource as apart of the portfolio of clean energy options. And we must utilize biomass energy along with the entire portfolio of renewable energy options geothermal, marine and freeflow hydro, solar, and wind along with high value energy efficiency including combined heat and power, geoexchange, among many others if we truly are sincere about addressing greenhouse gases, waste, water use, air-quality, and economic security.

Lead image: Corn field via Shutterstock

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Scott, founder and president of The Stella Group, Ltd., in Washington, DC, is the Chair of the Steering Committee of the Sustainable Energy Coalition and serves on the Business Council for Sustainable Energy, and The Solar Foundation. The Stella Group, Ltd., a strategic marketing and policy firm for clean distributed energy users and companies using renewable energy, energy efficiency and storage. Sklar is an Adjunct Professor at The George Washington University teaching two unique interdisciplinary courses on sustainable energy, and is an Affiliated Professor of CATIE, the graduate university based in Costa Rica. . On June 19, 2014, Scott Sklar was awarded the prestigious The Charles Greely Abbot Award by the American Solar Energy Society (ASES) and on April 26, 2014 was awarded the Green Patriot Award by George Mason University in Virginia.

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