Within the past century the pollution produced by automobiles and the oil industry has caught the attention of many environmentalists. With the status of the present-day society and the threat that the output of harmful emissions has placed on the atmosphere, environmentalists have become aware of the importance of finding an alternative fuel source. The chemical components of ethanol, as well as the characteristics of the compound with relation to the carbon dioxide in the atmosphere, and in turn, the notorious greenhouse effect, provide environmentalists and researchers with a potential alternative to the fuel source predicament.
Components of Ethanol
Ethanol is a high-octane alcohol containing oxygen, hydrogen and carbon (the empirical formula being C2H6O). The compound contains 35% oxygen; the addition of oxygen to a fuel results in a faster and more complete method of combustion, therefore reducing the output of harmful emissions into the atmosphere. As the fuel is combusted, the carbon dioxide is absorbed by the plants from which the ethanol was produced – generally grains, wheat and corn – therefore ‘recycling’ the carbon that was released. Ethanol is said to reduce tailpipe emissions by 30% and particulate matter, PM, by 50%. The formation of PM is reduced as ethanol dilutes the fragrant content in gasoline.
Recently, environmentalists have been looking for ways in which the output of pollutant emissions into the atmosphere can be reduced. Petroleum-based fossil fuels have been considered, but do not seem to be promising for the environment. Aside from being limited in supply, and containing benzene, a carcinogen, fuels such as gasoline are the major contributor of carbon dioxide emissions, a greenhouse gas. According to the Argonne National Laboratory, ethanol blends have reduced the release of harmful greenhouse gases by 18-29%. The study also concluded that in the year 2006, the use of ethanol in the United States alone decreased the C02- GHG, or greenhouse gas, emissions by roughly 8 million tons – this was estimated to be the equivalent of removing 1.21 million cars from the road.
Automobiles are a contributing factor to the emissions that pollute the atmosphere. Over 50% of pollution in the air comes from the vehicles on land. A specific group of automobiles, including older vehicles and those with various malfunctions, are often classified as “high-emitters”, and although these vehicles only account for 10% of total transportation, the emissions can be the most harmful to the atmosphere. In addition to “high-emitting” automobiles, ethanol is also proven to be a significant pollutant control strategy for vehicles such as ATVs, snowmobiles and motorcycles, which generally account for the release of a considerable percentage of harmful pollutants.
The production of carbon monoxide, and as a result, the absorption of this compound into the atmosphere, has been proven to be a leading cause of the formation of smog. In fact, according to the National Research Council, the emissions from carbon monoxide result in nearly 20% of smog formation. Organic compounds which are unstable can be the cause of the build-up of ozone in the atmosphere. Ethanol-based fuels, because they are of a higher volatility, are responsible for counterbalancing the release of any emissions that have evaporated into the atmosphere.
A key factor in considering the use of ethanol deals not only with the fact that this source is renewable, since it is produced from plants, but also that it is biodegradable. Ethanol is produced when organic matter is fermented, and because it is a natural substance, it biodegrades quickly and easily. Being that it is a non-toxic substance, the surface water, as well as the ground water, are not threatened and therefore remain pure. Researchers have been concerned that the rapid rate at which ethanol biodegrades may be a threat to the water and the land in the event that a gasoline spill occurred. Due to the fact that ethanol breaks down so quickly, environmentalists feared that benzene, a carcinogen, would remain in the environment longer. It was not taken into consideration however, that benzene is only a viable threat in gasoline.
Ethanol from Cellulose
Recent studies show that the production of ethanol from cellulose offers a promising reduction in the harmful GHG, or greenhouse gas emissions. Although ethanol is typically produced from grains, it can also be produced from cellulose, which is the most common organic compound on the earth. Although cellulose, the carbohydrate polymer found in a plant’s cell wall, is not as easy to produce as corn or other grains, it offers the use of many so-called “waste products” that would otherwise be disposed, provided that they could no longer be of any use. Cellulosic ethanol is more energy-efficient because the temperatures for distillation are considerably lower than for corn, and very little energy is required to produce the ethanol. In comparison to gasoline, production of cellulosic ethanol could reduce GHG emissions by as much as 80%.
Energy Balance of Ethanol
Although the topic tends to be debatable, recent studies show that a positive energy balance is produced by ethanol; ethanol produces more energy than is used during the production of the compound. According to the U.S. Department of Agriculture (USDA), ethanol yields 34% more energy than is used during the production process. The conflicting issues relating to the net energy are a result of an inconsistency in the data that was collected. An assumption about the co-products, the corn gluten feed, the corn oil and the distilled grains for example, was incorrectly made, therefore varying the results. These co-products – those that have a positive economic value and displace other products that take energy to make – were not considered to be part of the input energy. In the studies where this displacement was accounted for, it was proven that both the co-products of the corn and the ethanol itself yielded a positive net energy result.