Coal and Climate Change - A Lower Emission Future for Coal

Pathways to a Lower Emission future for Coal

Major emission reductions from coal mining and coal use willl come from:

1. Increasingly energy-efficient mining operations
2. Utilising coal-seam methane to prevent its release to the atmosphere
3. Improved coal preparation
4. Advances in power-station efficiency
5. Using coal by-products and wastes
6. Linking coal and renewable energy technologies
7. Capture and storage of carbon dioxide

1. Energy-efficient mining operations

The energy efficiency of processes associated with the excavation, extraction, handling and transportation of coal is constantly improving. This means less greenhouse gas emissions per tonne of coal mined and delivered to market.

See also: Clean Coal Technologies

2. Using coal-seam methane

Methane is a greenhouse gas which is released during mining operations.

Common practice is to vent this potentially explosive gas to the surface to reduce the serious safety hazard it poses in underground mining operations. 95% of methane from world coal mining is currently vented. (Pictured: Methane captured and used for power generation)

Methane can easily be flared to radically reduce its global warming potential, or captured for use as a valuable energy source for power generation. The technology for utilising coal seam methane is well developed and is being progressively implemented.

See also: Methane Capture and Use

3. Improved coal preparation

Coal preparation reduces moisture and ash content, sulphur, nitrogen and other contaminants. This results in reduced emissions of greenhouse gases and other pollutants when the coal is used. The crushing and grading of coal to meet specific end-use requirements also results in greater thermal efficiency, fewer post-combustion wastes and fewer greenhouse gas emissions.

See also: Coal Preparation

4. Advances in thermal efficiency

In electricity generation, thermal efficiency is a measure of how much useful energy can be extracted from a given amount of coal. Every 1% increase in thermal efficiency results in a 2-3% decrease in greenhouse gas emissions.

Thermal efficiency increased more than eightfold over the past century, from about 5% in 1900 to 45% for today's supercritical steam plants. The next generation of coal-fired power plants will push thermal efficiency towards 60%. Increased thermal efficiency reduces all pollutants, not just greenhouse gases.

See also: Clean Coal Techologies - Examples

5. Using coal by-products and wastes

Fly ash from coal-fired power stations and slag from steel making and smelting can be utilised by other industries, replacing the need to mine or obtain raw materials from other sources. For example, a 10% reduction in overall coal-related greenhouse gas emissions could be obtained if more fly ash were used in the production of cement. Fly ash and blast furnace slag can also be used in road construction.

6. Combining coal and renewable energy technologies

Combining coal with some renewable energy technologies can significantly reduce total emissions and may be the most cost-effective way to increase the use of renewable energy.

Biomass (for example wood, bagasse or other suitable plant material) can be burned with coal in conventional power stations. Co-firing in this way can increase the efficiency with which biomass is converted to useful energy from 20% for a stand-alone biomass plant to 35%.

Similarly, linking solar thermal systems with the steam cycle of a coal-fired power plant offers the potential to convert 40% of solar energy into electricity compared to 13% efficiency for stand-alone solar systems.

7. Capture and storage of carbon dioxide

The capture and permanent underground or deep ocean storage of carbon dioxide is emerging as a real option for radically reducing emissions from coal-based power generation. Technical solutions are already available and are being applied on a small scale, mainly to enhance oil recovery.

The main barriers to wider use of carbon dioxide capture and storage include the energy penalty, the cost of capture, proof of reliability, and the need to investigate the environmental impacts of storage. A number of countries have major research programs in capture and storage and there is increasing international collaboration.

See also: Carbon Capture and Storage

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