There are many efforts to make building more comfortable and to reduce the carbon dioxide emissions from buildings. For many years we tried to increase wall thickness of the wall insulation and roof insulation and adding the bottom insulation.

This seems logical, but I recently attended a seminar in where a speaker tried to make a comparison of as opposed to two major areas of new construction. These building were build year apart and built insulation levels in the store later far exceeded the first branch. Although the shops were of similar size, has a similar level of glass and skylights, the shop recently built, although it improved R-values (please refer to insulation R-Value chart), 43% costs warmer than the last. (more…)

air pollution problems created by coal combustion. Meanwhile, coal-fired power plants and industrial boilers spewed out tons of gaseous and particulate pollutants into the atmo- sphere. During combustion, the small amounts of sulfur and nitrogen in coal combine with oxygen to form sulfur dioxide (SO2), sulfur trioxide (SO3), and the oxides of nitrogen (NOx). (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.

It is a rare company prospectus that begins with a quotation from Goethe: “Whatever you can do, or dream you can, begin it. Boldness has genius, power, and magic in it.” But Lovins is not a normal entrepreneur, as anyone who has met this eccentric and disheveled but unmistakably visionary thinker knows. The founder of the Rocky Mountain Institute, a leading green think tank based in Old Snowmass, Colorado, thinks the car industry’s incremental approach to cutting emissions and improving fuel efficiency will never amount to much. He wants a complete redesign of the automobile, from the bottom up, and intends to show the big boys how it should be done. (more…)

Coal is still used to a small extent for home heating and cooking. In the homes of more affluent nations, coal is used for recreational or nostalgic reasons, rather than for routine heating and cooking. Coal stoves designed for this purpose are aesthetically attractive and are engineered for efficient operation with near-zero indoor air pollution. In contrast, coal used for cooking and heating in developing countries is burned in crude stoves with inadequate ventilation. In more developed countries, it is common to see coal source of energy. (more…)

Coal is an important energy source and energy consumption in United States as well as worldwide. It will remain so for many years particularly in many developing countries. Fossil fuels stay as the main energy sources to the U.S. economy, but we can not ignore the importance of coal for decades. Coal production provides the price stability and will continue to be an significant source for electricity generation. Coal utilization is the major source of hydrogen in the coming hydrogen-based energy economy and it will be a crucial source of gas to liquid process of fuels energy.

Coal utilization and the importance of coal as source of energy industry perspective will change over time. (more…)