Every year 24,000 people die prematurely because of pollution from coal-fired power plants.
Every year 38,000 heart attacks occur because of pollution from coal-fired power plants.
Every year 12,000 hospital admissions and 550,000 people suffering asthma attacks result from power plant pollution.
Every year, coal-fired power plants release 48 tons of mercury nationwide.
Power plants release over 40% of total U.S. C02 emissions, a primary contributor to global warming...
...and yet the coal industry wants you to believe that building more coal fired power plants in Michigan is a good idea!
...and now utilities want to burn (as biomass) our trees that capture and store harmful carbon dioxide and produce the oxygen we need to live
In response to the proposal to build a biomass gasification facility please consider the following:
CO2 emissions for equivalent amounts of energy generated
Olympia, WA—When coal and natural gas are converted to energy the amount of carbon dioxide (CO2) emitted is 210 and 117 pounds of carbon dioxide per million Btus of energy generated, respectively (1). When construction and demolition wood waste is converted to energy, CO2 emitted is 227 pounds per million Btus generated, based on 13.4 million Btus of energy per ton and 42% carbon content (2). Forestry residues such as forest floor wood, tree limbs or logging slash would have higher emissions due to higher moisture content and the presence of leaves and needles in the residues, both of which reduce energy generated. Taking into account emissions during production and distribution of these fuels adds up to 10% or more to their total emissions (3). These facts provide one of the supports for the claim that woody biomass is dirtier than coal and twice as dirty as natural gas.
When are CO2 emissions not really CO2 emissions?
We cannot grow new coal or natural gas within human scale time periods, but we can grow trees. Hence some argue that we should take account of this fact when calculating the climate impact of CO2 emissions from woody biomass. There are numerous complexities in figuring how to do this accounting.
There are the time and spatial scales over which to account for new tree growth. In other words, how many years and how many acres does it take to re-sequester the carbon released when woody biomass is converted to energy? EPA’s estimate of the time frame for re-sequestration is that, “…for a given amount of CO2 released today, about half will be taken up by the oceans and terrestrial vegetation over the next 30 years, a further 30 percent will be removed over a few centuries, and the remaining 20 percent will only slowly decay over time such that it will take many thousands of years to remove from the atmosphere” (4).
That’s nature’s re-sequestration rate without human intervention. Some believe re-sequestration time can be substantially shortened by active forestry management. Whether this can be done while maintaining habitat, biodiversity and other ecosystem functionalities at the same level as would exist without human intervention is an open question. For example, removal of woody debris from forests has an adverse impact on species that depend on wood waste for their existence (5).
Whatever the time required for re-sequestration of the instantaneously released CO2 from biomass conversion to energy it clearly places a constraint on the rate and spatial scale of woody biomass harvesting. There will be years of lead time before the rate of re-sequestration is equivalent to the rate of instantaneous carbon release from biomass conversion.
More importantly, conversion of woody biomass to energy is not the only option for biomass utilization. Manufacturing into wood and paper products, composting, and burying in landfills are three other options, all of which maintain storage of some of the carbon sequestered in biomass. Furthermore, whether re-sequestration happens at nature’s pace or at the accelerated pace of human forestry management, there is no necessary connection between re-sequestration and CO2 releases from biomass conversion to energy. Thus, if Evergreen students, faculty and staff believe they can manage the Evergreen forests so as to accelerate carbon sequestration without impairing the forest ecosystems, then that forestry management can be carried out regardless of the fate of any woody biomass wastes that might be generated by their forestry management activities.
In turn that means that we should compare the CO2 emissions for woody biomass management options to determine which provides the best climate benefit. I performed just such a life cycle assessment of some of these management options for clean construction and demolition wood wastes several years ago for Seattle Public Utilities (SPU) (6). Not surprisingly, the new products manufacturing option (which in that analysis was production of paper pulp) was better for the climate than conversion to energy or landfilling. The surprising result was that modern anaerobic landfilling was better than conversion to energy to replace natural gas. This is because in an anaerobic landfill over 80% of the carbon in wood wastes does not biodegrade, and instead continues to store the carbon originally sequestered from the atmosphere when the trees were growing prior to harvest (7).
In other words, regardless of the rate of CO2 re-sequestration through forestry management methods, storage of woody biomass wastes in landfills is better for the climate than converting those wastes to energy to substitute for energy generated from natural gas combustion.
The whole life cycle assessment story
Climate impacts are only one of the many public health and environmental impacts considered in a life cycle assessment. That’s because CO2, methane, nitrous oxide, chlorofluorocarbons, and other chemical compounds that cause climate change are not the only emissions to air, water and land that cause harm to humans, ecosystems and our environment. To evaluate the impacts of these other pollutants life cycle assessment has grouped the pollutants together in groups that cause similar impacts, just as the climate changing pollutants are grouped together and indexed according to their climate impacts relative to CO2. In my study for SPU I considered impacts caused by 6 of these groupings – pollutant emissions having human respiratory, human carcinogenic and human toxicity impacts; emissions causing ecosystems toxicity; emissions causing acidification impacts such as acid rain; and impacts causing eutrophication impacts such as fish mortality. For all six categories of public health and environmental impacts modern landfilling of wood wastes had impacts at least 50% below the levels of impacts from converting wood wastes to energy to replace natural gas combustion.
There are many technical details behind these results. One of the important ones is that the emissions from natural gas and wood waste conversion to energy came from EPA’s data on emissions of industrial boilers and furnaces (8). Because these emissions are from existing boilers and furnaces, some might argue that they are not relevant for the conversion technology proposed for Evergreen. Since we don’t have full emissions profiles (including all heavy metals, hazardous air pollutants and volatile organic compounds) for the proposed facility or for an equivalently up-to-date natural gas facility, it’s not possible to answer this argument directly. But what we do know are the results for existing industrial scale furnaces and boilers. We also know the results for home wood stoves and fireplaces versus natural gas furnaces. The former are the reason for Thurston County air quality attainment issues. Based on these results for small scale and large scale conversion methods for wood wastes and natural gas, and on the relative ease with which a solid versus a gas can be converted to energy, it’s virtually certain that an up-to-date natural gas facility will be similarly far less damaging to public health and the environment than an up-to-date wood waste conversion facility.
Jeffrey Morris, Ph.D. – Economics
(1) U.S. Energy Information Administration at http://www.eia.doe.gov/oiaf/1605/ggrpt/excel/CO2_coeffs_08.xls.