Transportation is another sector that has increased its relative share of primary energy use. This sector has serious concerns as it is a significant source of CO2 emissions and other airborne pollutants, and it is almost totally based on oil as its energy source. An important aspect of future changes in transportation depends on what happens to the available oil resources, production and prices. At present, 95% of all energy for transportation comes from oil. (more…)

Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive ecosystems, decreased visibility, negative human health effects, and increased degradation of certain stone building materials and cultural resources, especially those made of limestone and marble. Fine particulate nitrate and sulfate particles associated with acid deposition are implicated in aggravating cardiorespiratory diseases such as asthma and chronic bronchitis, especially in urban areas. In many cases estimating the impact of acid deposition on various ecosystems can be a difficult process because acid deposition is only one of many impacts that can effect a response. However, wet and dry acid deposition has been documented as a major factor in the following ecosystem responses. (more…)

In this new century, there is considerable pressure on the top six automakers to reduce their environmental and ecological footprint calculation. The automaker that wins the race to build and sell the superior car will shape consumer preferences, thereby boosting sales and profits. The winning firm will fashion a corporate strategy that drives automobile emissions to near zero while simultaneously providing high levels of performance, safety, and comfort. (more…)

Although some scientists and critics still dispute that human caused greenhouse gases are causing climate change, the majority of scientists and climate experts assert that global warming is a serious problem that could have devastating consequences unless action is taken to reduce fossil fuel emissions. In 2007, for example, the Nobel Prize–winning Intergovernmental Panel on Climate Change (IPCC), a scientific body charged by the United Nations with summarizing the best climate science, concludes that evidence of the warming of our climate is “unequivocal.” (more…)

The evidence on the environmental Kuznets curve indicates that national environmental policies differ between high-income and low-income countries, and that as a result of income growth pollution in the Northern hemisphere may be reduced over time at the cost of increasing pollution in the Southern hemisphere. There have been concerns that this process is reinforced by international trade of goods and by foreign direct investment between North and South. More stringent environmental policies in the North force pollution-intensive industries located in the North to raise their prices relative to the prices charged by firms in the South. (more…)

Smoke from biomass and coal combustion contains a large number of pollutants with known health hazards, including particulate matter, carbon monoxide, nitrogen dioxide, sulfur oxides (mainly from coal), formaldehyde, and polycyclic organic compounds (e.g., carcinogens such as benzo[a]pyrene). The concentrations of each of these pollutants vary among the different forms of solid fuels, with animal dung and crop residues having some of the highest level emissions to environment of particulate matter, one of the important indicator pollutants for health effects. (more…)

A combination of legislation and technology has helped clean up many of the world’s coal-burning plants. Both developed and developing countries have adopted increasingly stringent environmental regulations to govern emissions from coal-fired power plants. In the United States, all coal-fired power plants built after 1978 must be equipped with postcombustion cleanup devices to capture pollutants before they escape into the atmosphere. Cyclones, baghouses, and electrostatic precipitators filter out nearly 99% of the particulates. Flue gas scrubbers use a slurry of crushed limestone and water to absorb sulfur oxides from flue gas. The limestone reacts with the sulfur dioxide to form calcium sulfate, which may be used to produce wallboard. Staged combustion and low-NOx burners are used to burn coal to minimize NOx formation. Another strategy, selective catalytic reduction, reacts ammonia with NOx over a catalyst to produce nonpolluting nitrogen and water vapor.

Conventional coal-fired power plants capture pollutants from the flue gas after it leaves the boiler. Circulating fluidized bed (CFB) combustors capture most of the pollutants before they leave the furnace. Crushed coal particles and limestone circulate inside the CFB combustor, suspended by an upward flow of hot air. Sulfur oxides released during combustion are absorbed by the limestone, forming calcium sulfate, which drops to the bottom of the boiler. The CFB combustor operates at a lower temperature (14001F) compared to pulverized coal (PC) boilers (27001F), which also helps reduce the formation of NO x .

Precombustion coal cleaning is another strategy to reduce sulfur emissions by cleaning the coal before it arrives at the power plant. Sulfur in coal is present as pyrite (FeS2 ), which is physically bound to the coal as tiny mineral inclusions, and as ‘‘organic sulfur,’’ which is chemically bound to the carbon and other atoms in coal. Pyrite is removed in a coal preparation plant, where coal is crushed into particles less than 2 inches in size and is washed in a variety of devices that perform gravity-based separations. Clean coal floats to the surface, whereas pyrite and other mineral impurities sink. Additional cleaning may be performed with flotation cells, which separate coal dust from its impurities based on differences in surface properties. Precombustion removal of organic sulfur can be accomplished only by chemical cleaning. So far, coal combustion emissions and chemical cleaning has proved to be too costly, thus flue gas scrubbers are often required to achieve near-complete removal of sulfur pollutants.

The tightening of environmental regulations is likely to continue throughout the world. In the United States, for example, by December 2008, it is anticipated that coal-fired power plants will have to comply with maximum emission levels for mercury. Emissions of mercury and other trace metals, such as selenium, are under increasing scrutiny of coal combustion emissions because of suspected adverse effects on public health.

Coal is sometimes combusted with waste material as a combined waste reduction/electricity production strategy. The disposal of waste from agriculture and forestry (biomass), municipalities, and hospitals becomes costly when landfill space is limited. Some wastes, particularly biomass feedstock, are combustible, but their low energy density (compared with coal) limits their use as an electricity production fuel. Blending coal with these fuels provides an economical method to produce electric power, reduce waste, and decrease coal plant emissions. Most wood wastes, compared to coal, contain less fuel nitrogen and burn at lower temperatures. These characteristics lead to lower NO x formation. In addition, wood contains minimal sulfur ( o 0.1% by weight) and thus reduces the load on scrubbers and decreases scrubber waste biomass.

Numerous electric utilities have demonstrated that 1–8% of woody drying biomass can be blended with coal with no operational problems. Higher blends may also be used, but require burner and feed intake modifications as well as a separate feed system for the waste fuel. Cofiring in fluidized bed boilers may avoid some of these drawbacks, but the economics of co-firing are not yet sufficiently attractive to make it a widespread practice.

There are various and somewhat complementary reasons to foster the growth of renewable energy sources in Europe. A major incentive for renewable energy sources policies in the past two decades has been to reduce the environmental impact of energy use both locally (e.g., pollutant emission reduction) and globally (e.g., greenhouse gas and carbon emissions reduction). In some countries, concerns about the safety of nuclear power generation have motivated the search for renewable energy sources. Another motivation for replacing foreign fossil and nuclear fuels with domestic renewable energy sources relates to security issues and Europe’s growing dependency on foreign energy sources. (more…)

Fuel cell vehicles are being developed because they promise to meet the requirements expected of automobiles in a market increasingly constrained by environmental and resource limitations. Air pollution and oil dependence have been persistent challenges for vehicles powered by petroleum fuels (gasoline and diesel). Global warming presents a new challenge in the need to limit carbon dioxide (CO) emissions from fossil fuel combustion. (more…)

At present, in the United States and worldwide, motor vehicles are fueled almost exclusively by petroleum based gasoline (or reformulated gasoline) and diesel fuels. Since the first oil price shock in 1973, efforts have been made to seek alternative fuels to displace gasoline and diesel fuels and achieve energy and environmental benefits. Some of the alternative fuels that have been researched and used are liquefied petroleum gas (LPG), compressed natural gas (CNG), liquefied natural gas (LNG), methanol (MeOH), dimethyl ether (DME), Fischer– Tropsch diesel (FTD), hydrogen (H 2 ), ethanol (EtOH), biodiesel, and electricity. Production processes associated with gasoline, diesel, and each of these alternative fuels differ. (more…)