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Fossil fuels have been so much part of our everyday lives for so long now, that it is sometimes hard to believe that their use could be harmful. Another problem in this regard is that their negative impacts are often subtle, and therefore, are difficult to properly appreciate. However, as we deplete these fossil reserves at an ever increasing rate (especially in countries like China and India), the negative impacts of using them are becoming more and more evident.

Generations of greenhouse gases and the associated risk of global warming, along with emissions of nitrogen oxides, sulfur oxides and mercury, are among the most serious environmental consequences of burning fossil fuels. While the visual evidence of these problems might not be revealed to all of us on a daily basis, the EPA has collected a considerable amount of credible data to verify them. In fact, if one spends any time at all browsing the EPA web site (http://www.epa.gov/), it can become quite scary. The objective of this article is to raise awareness of these problems, and to emphasize that bioenergy can play a role in alleviating them.

Global Warming

When scientists started talking more about global warming a few decades ago many of us just considered it to be mostly unsubstantiated hype. However, there is now so much evidence to indicate that global warming is real, and a serious threat to our sustain-ability, that even the most skeptical have to take it seriously. Those who have doubts might want to consult this site: http://yosemite.epa.gov/oar/globalwarming.nsf/content/index.html.

Global climate change is being caused by increased greenhouse gases in the atmosphere. Rising levels of atmospheric carbon dioxide resulting from combustion of fossil fuels is probably the major cause of this problem. Burning these fuels, including natural gas, amounts to taking carbon out of the ground where it is essentially harmless, and pumping it into the air, thus adding to the atmospheric pool of CO2. And since the U.S. is the largest user of fossil fuel in the world (with only 5% of the world’s population we burn 25% of the world’s oil), we bear much of the responsibility for this problem.

In contrast to combustion of fossil fuels, forests and crops remove carbon from the atmosphere as they grow (they do not get carbon from the soil). If biomass from these sources is burned to generate energy, carbon is simply cycled back into the atmosphere where it came from. Therefore, bioenergy is carbon-neutral. In fact, if perennial energy crops like trees or switchgrass are planted on land that was previously in annual crops, the process can even be carbon-negative because carbon will be added to or sequestered in the soil by the energy crop.

Other Emissions and Acid Rain

According to the EPA, scientists discovered, and have confirmed, that sulfur dioxide (SO2) and nitrogen oxides (NOX) are the primary causes of acid rain. In the US, about two thirds of all SO2 and one quarter of all NOX comes from electric power generation that relies on burning fossil fuels like coal, while one half of all NOX comes from combustion of transportation fuels in vehicles. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid.

Acid rain causes acidification of lakes and streams and contributes to damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, it accelerates the decay of building materials and paints, including the finish on automobiles, irreplaceable buildings, statues, and sculptures that are part of our nation’s cultural heritage. Prior to falling to the earth, SO2 and NOX gases and their particulate matter derivatives, sulfates and nitrates, contribute to visibility degradation and can harm public health.

NOX also has other negative effects. Ground-level ozone (smog) is formed when NOX and volatile organic compounds (VOCs) react in the presence of sunlight. Related adverse effects of smog are damage to lung tissue and reduction in lung function in children, people with lung diseases such as asthma, and people who work or exercise outside. Ozone can be transported by wind and cause health impacts far from original sources. Millions of Americans live in areas that do not meet the health standards for ozone.

Mercury emissions constitute another serious health hazard related to combustion of coal. People in the U.S. are mainly exposed to methyl-mercury, an organic compound, when they eat fish and shellfish that contain methylmercury. For fetuses, infants, and children, the primary health effect of methylmercury is impaired neurological development.

Methylmercury exposure in the womb, which can result from a mother’s consumption of fish and shellfish that contain methylmercury, can adversely affect a baby’s growing brain and nervous system. Impacts on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills have been seen in children exposed to methylmercury in the womb. This problem is most severe in the northeastern USA where people, especially pregnant women, have been advised to avoid consumption of fish.

Can Bioenergy Help?

While bioenergy will not provide a quick or complete solution to the problems related to emissions from combustion of fossil fuels, it has potential to alleviate these problems. For example, tests conducted by the Southern Company and Alabama Power at Gadsden showed that co-firing switchgrass with coal reduced the emissions of CO2, SO2 and mercury. Other studies have shown that co-firing biomass with coal can also reduce emissions of NOX.

It has been widely recognized that the negative impacts of emissions from fossil fuels on the environment and human health are so serious that they simply have to be reduced. Consequently, there are now credits available for reduction of SOX and NOX, and on March 15, 2005, the federal government announced the first ever regulations that will attempt to reduce mercury emissions. These regulations and incentives could at least partially offset the higher price of biomass compared to coal, and this issue is currently under careful assessment in Alabama.