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.

Energy exists in many forms. Some of energy forms are simple to use and identify as energy. But other forms of energy can not be seen until the energy released. Some forms of energy like light and sound, they carry energy from one place to another. There are also vibrating objects that carry the kinetic energy that makes the sound. The energy passes through the wave where the wave was originated. The higher the wave, it gives more energy. Light is also one form of energy. A light beam or light ray brings out energy from where there was light. This energy is often referred to as radiation energy. (more…)

Electric and gas utilities’ Research & Development activities deal nearly exclusively with energy conversion, distribution, and energy usage (at least to the extent that these firms still focus on these core businesses). Although detailed data on utility Research & Development are not collected systematically, it seems that Energy R&D spending by many utilities has declined during the past decade or so. For example, a 1996 survey by the U.S. General Accounting Office (GAO) found that the combined Research & Development spending of the 112 largest operating utilities in the United States dropped from $708 million in 1993 to $476 million in 1996. (more…)

The wind has covered every Sunday morning more than 50 percent of electricity & energy demand. It has also achieved the record high of 11 546 megawatts with simultaneous electric generation. (more…)

Germany is considered a world leader in wind energy deployment, with electricity production from wind having gone up more than eightfold—from 670 to more than 5500 GWh—between 1993 and 1999. In 1999, Germany had more than 4000 MW installed capacity. The prices also declined substantially over this period, indicating a learning rate of approximately 8%, and it is estimated that for each deutschemark (DM) spent by the government in subsidizing learning, market actors provided 2.1 DM. Furthermore, the manufacturing base for wind energy technologies, including indigenous firms as well as joint ventures, continues to expand in Germany. (more…)