Coal Power Plant Schematic Diagram

Generation of electricity in a coal-fired steam station is similar to a nuclear station. The difference is the source of heat. The burning of coal replaces fissioning, or splitting , of uranium atoms as the source of heat. The heat turns water to steam in steam generators. The steam is then used to drive turbine generators.

1. Firebox
Before the coal is burned, it is pulverized to the fineness of talcum powder. It is then mixed with hot air and blown into the firebox of the boiler. Burning in suspension, the coal-air mixture provides the most complete combustion and maximum heat possible.

2. Boiler
Highly purified water, pumped through pipes inside the boiler, is turned into steam by the heat. At temperatures of up to 1,000 degrees Fahrenheit and under pressures up to 3,500 pounds per square inch, the steam is piped to the turbine.

3. Turbine|Generator
The enormous pressure of the steam pushing against a series of giant turbine blades turns the turbine shaft. The turbine shaft is connected to the shaft of the generator, where magnets spin within wire coils to produce electricity.

4. Condenser
After doing its work in the turbine, the steam is drawn into a condenser, a large chamber in the basement of the power plant. The condenser is an important part of a steam-electric unit, whether nuclear or coal-fired. This device condenses the steam leaving the turbines back into water so that it can be used over and over again in the plant. This essential cooling process requires large quantities of water; thus, most steam-electric stations are located on lakes or rivers.

5. Condenser Cooling Water
Millions of gallons of cool lake water are pumped through a network of tubes that runs through the condenser. The water in the tubes cools the steam and converts it back into water. After the steam is condensed, it is pumped to the boiler again to repeat the cycle.


Coal Fired Power Plant Schematic Diagram

Coal-fired Power Plant

A coal-fired power plant produces electricity, usually for public consumption, by burning coal to boil water, producing steam which drives a steam turbine which turns an electrical generator.

Coal is a relatively cheap fuel with some of the largest deposits in politically stable regions (China, India and the US) thus generally offering a more stable supply than natural gas and oil, the largest deposits of which are located in the more politically volatile Persian Gulf. The combustion of any fuel, including coal, emits large amounts of carbon dioxide into the atmosphere, contributing to global warming; coal also emits other pollutants such as sulfur, nitrogen, small particulates, and heavy metals like mercury and uranium (which is naturally present in coal). These other pollutants have been linked to acid rain, smog, and a variety of health problems.

As of 2009 the largest coal-fired power plant is Kendal Power Station, South Africa. The world's most energy-efficient coal fired power plant is the Avedøre Power Plant in Denmark.

Clean Coal Technology

Clean coal technology is an umbrella term used to describe technologies being developed that aim to reduce the environmental impact of coal energy generation. These include chemically washing minerals and impurities from the coal, gasification, treating the flue gases with steam to remove sulfur dioxide, carbon capture and storage technologies to capture the carbon dioxide from the flue gas and dewatering lower rank coals (brown coals) to improve the calorific value, and thus the efficiency of the conversion into electricity.

Clean coal technology usually addresses atmospheric problems resulting from burning coal. Historically, the primary focus was on sulfur dioxide and particulates, since it is the most important gas in the causation of acid rain. More recent focus has been on carbon dioxide (due to its impact on global warming) as well as other pollutants. Concerns exist regarding the economic viability of these technologies and the timeframe of delivery, potentially high hidden economic costs in terms of social and environmental damage, and the costs and viability of disposing of removed carbon and other toxic matter.

Coal, which is primarily used for the generation of electricity, is the second largest domestic contributor to carbon dioxide emissions in the USA. The public has become more concerned about global warming which has led to new legislation. The coal industry has responded by running advertising touting clean coal in an effort to counter negative perceptions, as well as by putting more than $50 billion towards the development and deployment of clean coal technologies, including carbon capture and storage. The expenditure has been unsuccessful to date in that there is not a single commercial scale coal fired power station in the US that captures and stores more than token amounts of CO2.

The world's first "clean coal" power plant went on-line in September 2008 in Spremberg, Germany. The plant is state-owned and has been built by the Swedish firm Vattenfall. The plant is state owned because of the high costs of this technology, since private investors are only willing to invest in other sources such as nuclear, solar and wind. The facility captures CO2 and acid rain producing sulfides, separates them, and compresses the CO2 into a liquid state. Plans are to inject the CO2 into depleted natural gas fields or other geological formations. This technology is considered not to be a final solution for CO2 reduction in the atmosphere, but provides an achievable solution in the near term while more desirable alternative solutions to power generation can be made economically practical.

According to the United Nations Intergovernmental Panel on Climate Change, the burning of coal, a fossil fuel, is a major contributor to climate change and global warming. As 25.5% of the world's electrical generation in 2004 was from coal-fired generation, reaching the carbon dioxide reduction targets of the Kyoto Protocol will require modifications to how coal is utilized.

Some in the coal industry and the U.S. Department of Energy refer to carbon capture and sequestration (CCS) as the latest in "clean coal" power plant technologies. The "clean coal" terminology is generally not endorsed by professionals in CCS, and is actively opposed by environmental organizations that favor CCS. CCS is a means to capture carbon dioxide from any source, compress it to a dense liquid-like state, and inject and permanently store it underground. Currently, there are more than 80 carbon capture and sequestration projects underway in the United States. All components of CCS technology have been used for decades in conjunction with enhanced oil recovery and other applications; commercial-scale CCS is currently being tested in the U.S. and other countries. Proposed CCS sites are subjected to extensive investigation and monitoring to avoid potential hazards, which could include leakage of sequestered CO2 to the atmosphere, induced geological instability, or contamination of aquifers used for drinking water supplies.

Supporters of clean coal use the Great Plains Synfuels plant to support the technical feasibility of carbon dioxide sequestration. Carbon dioxide from the coal gasification is shipped to Canada where it is injected into the ground to aid in oil recovery. Supporters acknowledge that economics can be problematic for carbon sequestration.