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Ellen Moyer, Ph.D. Headshot

Burning Trees to Make Electricity -- What Are They Thinking?

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The operative word is "they" instead of "we" because 81 percent of Americans think that other energy producing options should be explored first before biomass energy production is explored, according to a recent survey. But our public servants apparently think they know better than the public they are serving. Industry lobbyists have been hard at work selling the idea that biomass energy is clean, green, and renewable. It was chilling to listen to the U.S. Senate Committee on Energy and Natural Resources hearings on the Federal Clean Energy Standard (May 17, 2012), in which biomass energy was advocated while the vast potential of increasing energy efficiency to reduce our demand was barely mentioned.

Wood-burning electrical power plants, or "biomass plants," as explained below, are not clean, green, or renewable. If the U.S. national park system is "America's Best Idea," as Ken Burns says, then biomass plants are America's worst idea. Biomass plants devour many things of great value -- trees, wildlife habitat, soil fertility, water, petroleum, and money, and produce a multitude of damaging byproducts -- greenhouse gases, other air pollutants, water pollution, ash, adverse health impacts, and economic damage. It would be a challenge to design a more damaging activity if one tried. However, recognition of the devastating effects has been slow to take hold, because the term "biomass plant" sounds "green" and due to our obsessive-compulsive desire for more energy that does not involve fossil fuels, at any cost.

Biomass plants can burn trees, contaminated wood (such as "construction and demolition wood" that can include painted or pressure-treated wood), tires, or just about anything that can burn. Many biomass plants burn whole trees, which biomass plant developers often refer to euphemistically as "forest debris" or "waste wood." A 2011 report estimates that there are approximately 250 biomass plants operating in the U.S., with approximately 230 more proposed. The proposed plants are typically larger and range from 25 to more than 100 megawatts in capacity.

Of all the available combustion-based electricity generation technologies, biomass plants are the least efficient, converting to electricity only 20 to 25 percent of the energy in the wood. Some of the remaining energy is used to vaporize the water in the wood, and the rest is often discharged to the atmosphere using humongous quantities of river water for cooling. A typical 50 megawatt plant requires 800,000 gallons per day of fresh water, vaporizing 85 percent and returning 15 percent to the river heated and contaminated.

Because of their supreme inefficiency, gargantuan quantities of fuel are required. If all the trees in the U.S. were burned for biomass energy, it would meet our national energy needs for only one year. A typical 50 megawatt biomass plant burns 1.2 tons of wood each minute. The impacts on forests, and the wildlife that depend on them, are devastating. In addition, when trees are mined from the forest, soil nutrients are removed rather than recycled. Nutrient depletion thus renders the process of biomass production for energy unsustainable.

Despite industry-funded fuel supply studies to the contrary, the supply of nearby trees is quickly exhausted. A common strategy is for biomass plants to then switch to burning contaminated wood for fuel. This is how more money can be made, because rather than having to purchase a resource (green wood chips), now biomass plant owners are paid to take a waste (contaminated wood). Once the expensive incinerators are built, regulatory agencies find it hard to say no to requests for fuel switching.

Also due to their inefficiency, for each unit of electricity generated, biomass plants emit more carbon dioxide than any other energy source, for example, about 1.5 times that of coal for each unit of electricity generated. This reality is often countered by arguments based on a conceptual error made early on that took on a life of its own and has been difficult to eradicate, much like how the belief that the sun revolved around the earth was tenaciously held and only released with great difficulty. This is the notion that burning wood is "carbon neutral," that the carbon emitted during combustion is reabsorbed by growing trees. What was not considered is the mismatch in rates -- while it takes a minute to burn a tree in a biomass plant, it takes decades to grow a tree back. Oops!

The science is only beginning to convince the energy establishment to correct this major gaffe. In the meantime, while it is (rightly) regarded as bad for the climate to burn tropical rainforests, somehow it is still regarded as not only acceptable but even worthy of economic incentives to burn temperate forests in an incinerator, after additionally burning fossil fuels to cut the trees, chip them into small pieces, and transport them to the incinerator. As if that weren't enough of a climate impact, often petroleum is sprayed on the green wood chips to get them to ignite.

Biomass plants thus not only emit more carbon dioxide than any other energy technology, they destroy the very trees that sequester carbon dioxide. Recent research shows that the world's forests are much more important in the carbon cycle than previously thought, soaking up one-third of all fossil fuel emissions. At the same time, forest logging releases more than one quarter of all carbon dioxide emissions stemming from human activity. When developed countries burn their own forests for electricity, it shatters their credibility when they then ask developing countries to preserve their forests in order to mop up carbon dioxide emissions that are mainly caused by energy use in the developed countries.

As yet another consequence of their bottom-of-the-barrel efficiency, biomass incinerators (even after air pollution control equipment) release copious amounts of a wide array of air pollutants besides carbon dioxide, including particulates (soot), carbon monoxide, sulfur oxides, nitrogen oxides, heavy metals, volatile organic compounds, radionuclides, and dioxins. Biomass plant developers admit in their air permit applications that their projects will routinely emit air pollutants. Something they don't admit is that fuel pile fires are a common occurrence when fuel is stored uncovered outdoors, as is invariably the case due to the mammoth fuel quantities required. Fires often burn for weeks, with no emissions controls.

Because routine biomass plant air emissions increase human morbidity and mortality by causing or exacerbating asthma, heart disease, and cancer, numerous medical societies have spoken out forcefully against biomass plants. For example, the Massachusetts Medical Society, with over 23,000 physicians and medical students, adopted a resolution that states that biomass power plants "pose an unacceptable risk to the public's health by increasing air pollution."

Another dangerous byproduct that comes out the back end of a biomass plant is ash. A typical 50 megawatt biomass plant produces 1.5 tons of ash per hour. Ash from burning wood (even trees directly from the forest) contains dioxins and heavy metals such as arsenic. Another concern is radionuclides such as cesium-137 that are released from nuclear testing and accidents and are sequestered by trees and thus end up in the ash. Radionuclides and metals are released in air emissions or ash - those are the only two possibilities. Regulators turn a blind eye to radionuclides, however, and do not require testing for radionuclides. They likewise usually do not require testing for dioxin, a "known human carcinogen." Up to 80 percent of wood ash generated in northeastern U.S. is landspread on agricultural soils.

Partly owing to their inefficiency, biomass plants also require massive infusions of cash in order to be financially viable (unless they are allowed to burn contaminated wood). They receive various forms of tax-payer and rate-payer subsidies, in the form of Renewable Energy Credits, investment and production tax credits, and loan guarantees, which cost the public billions of dollars on top of the cost paid for the electricity itself. This is corporate pork on steroids, and furthermore, these subsidies divert funds that could instead be used to promote clean, renewable energy.

Proponents argue that biomass plants create jobs. However, ravaging forests destroys tourism jobs, and the biomass plant jobs created are few and costly. The investment required to create each permanent full-time job typically exceeds $3 million. Biomass plants also hurt the economy by driving down nearby property values (one reason they are invariably sited in poor communities with few resources to fight back) and driving up the price of wood needed for productive purposes.

Trees are worth far more than their energy content, cleaning the air and water, moderating the water cycle, providing earth's heat shield, housing and feeding animals, nourishing our souls, and providing other services we are only beginning to understand. It is evidence of our sense of disconnectedness from the natural world that we would allow trees to be valued merely for their energy content.

Biomass plant developers argue that biomass plants should be "part of the energy mix." Biomass plants don't belong in our modern energy portfolio any more than the muscle power of slaves or animals. They are no more appropriate than slide rules in modern computing, blood-letting in modern medicine, celestial spheres in modern astronomy, spontaneous generation in modern biology, or horses and buggies in modern transportation. We need to move from dirty combustion technologies to cleaner options such as solar, geothermal, wind, conservation, efficiency, hydropower, and fuel cells. Certainly any of these technologies must be implemented with care and intelligence. But it is past time for the combustion era to come to a close, and with increasing atmospheric carbon dioxide concentrations, we need our trees now more than ever before.

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