Tuesday, August 17, 2010

Coal – Introduction and some quick facts

Introduction to coal

Coal is classified as fossil fuel, and it is the main energy source for electricity production in the world. This however also means that coal is the main source of carbon emissions in the world meaning that coal significantly contributes to climate change issue. Coal is composed primarily of carbon along with variable quantities of other elements, mostly sulfur, hydrogen, oxygen and nitrogen.

Coal has a long history of use, and its use started somewhere during the Bronze Age (3000–2000 BC). Fast developing economies like China and India owe their economic success to coal, mostly because coal is still the cheapest energy option, and is widely available in many countries across the globe. Coal is extracted from the ground by mining, either underground or in open pits.

The total known coal deposits recoverable by current technologies should last for more than 100 years. On the other hand coal consumption is constantly increasing and some energy experts even believe that maximal coal production could be reached within the decades.

Coal – World's leading fuel to generate electricity

As said in introduction coal is the main source of electricity in the world. So we could say that this is its primary use. If we look at the actual numbers we can see that world coal consumption was about 6,743,786,000 short tons in 2006, and this number is expected to increase 48% to 9.98 billion short tons by 2030, even despite the ongoing climate change issue. Many people connect coal mostly to China but United States is also very dependent on coal, and United States consumes about 14% of the world total, using 90% of it for generation of electricity. Coal generates around 54% of US total electricity.

How is coal used for electricity generation? The most common process to generate electricity from coal includes pulverization and combustion in a furnace with a boiler. To simplify the things the much as possible the furnace heat converts boiler water to steam, which is then used to spin turbines, and turbines turn generators to create electricity. Efficiency of this process has been improved over the time, and the best way to increase efficiency is to increase the combustion temperature. Coal looks likely to remain the world's leading fuel to generate electricity for many years, and today about 40% of the world's electricity comes from coal, and approximately 49% of the United States electricity comes from coal.

Coal power plant.

Coal – Environmental impact

Many environmentalists will agree that burning coal is the most polluting method for producing electricity, and is causing huge environmental damage. The worst thing that happens in this process is of course the production of greenhouse gases (mostly carbon dioxide emissions) by burning coal, but carbon emissions are not the only negative thing in this process as there are also many other harmful compounds released during coal burning. It also has to be said environmental problems connected with coal are not only limited to the burning process. The extraction of coal, its transportation, storage and disposal of all create additional environmental issues.

The total amount of pollution caused by burning coal depends on the type of technology that is used for burning. New coal-fired power plant technologies are emerging with the ability to reduce the amount of carbon emissions and other harmful compounds released during the burning process. Integrated gasification combined cycle (IGCC) combustion is the best example of this new technology and some experts say this significantly reduces harmful carbon emissions. Despite certain reductions in carbon emissions from the use of IGCC technology, coal fired power plants will still have very negative impact on environment. A typical (500 megawatt) coal plant burns 1.4 million tons of coal each year. If we look at the United States alone we can see that there are about 600 coal power plants in US.

Carbon emissions are one problem connected with coal burning and air pollution is another. Air pollution is a major cause of environmental degradation, and there are also sulfur dioxide and nitrous oxides being released into the atmosphere causing acid rain and lung problems in humans and animals. Together with these harmful particles there are also some amounts of mercury, arsenic and lead, all of which can have serious health impact on living organisms.

And there is also the problem with the waste. The waste created from the coal burning is also very harmful to our environment. The sludge from smoke stack scrubbers is toxic, containing a number of heavy metals that can potentially contaminate the environment. Large quantities of coal waste are stored on site at the power plant, and thus it can easily enter the water supply of the surrounding area, contaminating it. When we talked about the water then I should also point out that the water used to cool the coal power plants is often sourced from a local water body and then simply pumped back after it has been used. This hot water, often containing chlorine or other chemicals, can result algal blooms and some other environmental problems.

The extraction and transportation of coal to a power plant is also connected with the number of different environmental issues. Since coal is predominantly mined from near the surface, this often causes damage to nearby ecosystems as many of the ecosystems above are degraded or sometimes even completely removed. Coal is usually transported by diesel trains over great distances, meaning that there's an extra releasing of carbon dioxide and other harmful particles. And there is also coal dust that once produced contributes to particulate matter in the air (air pollution).

Scientists: We are destroying earth.
Government: Could you kindly rephrase that in equivocal, inaccurate, vague, self-serving and roundabout terms that we can all understand.

Clean coal technologies

Since coal is connected with large amounts of greenhouse gas emissions it is no surprise that science and technology are on the lookout for new clean coal technologies, which would be burning coal without adding significantly to global carbon dioxide levels. Today, burning coal produces about 9 billion tones of carbon dioxide each year which is released to the atmosphere, and many energy experts hope that some new clean coal technology will successfully address this issue. The most promising of clean coal technologies look to be carbon capture and storage technology though it has to be said that this technology hasn't yet been optimized for the scale required in coal-burning power plants, and no commercial-scale power plants are operating with this process yet. But perhaps FutureGen project will change that.

US Department of energy has recently announced the $1.3 billion FutureGen project to design, build and operate an almost emission-free coal-based electricity and hydrogen production plant. The FutureGen initiative would have comprised a coal gasification plant with additional water-shift reactor, and this would produce both hydrogen and carbon dioxide. FutureGen project would also involve development of the ITM oxygen separation technology. According to the calculations around 700,000 tonnes of CO2 per year would then be separated by membrane technology and sequestered geologically. The hydrogen would have been be burned in a 275 MWe generating plant and in fuel cells. Construction of FutureGen was due to start in 2009, for operation in 2012, with target of 90% carbon capture. The project was designed to validate the technical feasibility and economic viability of near-zero emission coal-based generation.

Coal Reserves

China is currently the world's largest coal producer, followed by United States and India. At the end of 2006 the recoverable coal reserves amounted to around 800 or 900 gigatons. If we were to look at the current rates of extraction and use this should last fro around 132 years.

British Petroleum, in its 2007 report, estimated at 2006 end, there were 909,064 million tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio. This number however only includes reserves classified as "proven", and in many cases, companies are aware of coal deposits that have not been sufficiently drilled to qualify as "proven".

According to the BP's Statistical Review of World Energy in 2009 global proven coal reserves are at the highest levels of all time. Global reserves of coal were at 826,001 million tons at the end of 2009. This is 119 years of production at 2009 production levels and the United States has the largest share (28 percent) of these coal reserves.

If we compare coal with other fossil fuels (oil and natural gas) we can see that coal has the most widely distributed reserves; coal is mined in over 100 countries, and on all continents except Antarctica. The largest reserves are found in the USA, Russia, Australia, China, India and South Africa


Despite obviously having very bad negative impact coal still remains the mostly used energy source in the world. This is because coal is the cheapest energy option for many countries in the world, and the economy still outweighs ecology when it comes to energy.

Coal looks very likely to remain dominant energy source for at least next few decades, despite significantly contributing to climate change and air pollution. The only hope are clean coal technologies (especially carbon capture and storage technology) but these technologies despite looking promising still seem to be many years away before being implemented on global scale, and in the meantime coal production is in the constant rise, especially in the new fast developing economies such as China and India.

If climate change issue gets out of hand then coal could be easily regarded as the major culprit for this.

No comments: