The Daily Star
Committed to PEOPLE'S RIGHT TO KNOW
Vol. 5 Num 1088
Sat. June 23, 2007
Coal -- the energy resource for 21st centuryDr. Rafiqul IslamWorld's population is expected to reach over 8 billion by 2030, from its current level of 6.4 billion and consequently global energy demand will grow by almost 60 percent by 2030 and rise to 16.5 billion tones of oil equivalent per year.
Fossil fuels and in particular coal will meet up this challenge in future. Nuclear energy though provides a significant proportion of energy in some countries, but in general it faces serious public opposition.
Renewable energies are growing fast, but make up only a small part of global energy production -- the International Energy Agency (IEA) predicts that by 2030 only 14 percent of total energy demand will be met from renewable sources. In fact its not wise to depend on a single source of energy.
Coal can play a unique role in meeting the demand for a secure energy supply. Coal is globally most abundant and economical as well of all fossil fuels, which can be used for both power generation and industrial applications.
The production and utilization of coal is based on well-proven and widely used technologies. Coal faces environmental challenges. However, research efforts into improving the efficiency of coal fired electricity generation and technologies for carbon capture and storage offer routes to reduce carbon dioxide emissions. Coal reserves are significantly more abundant and much more widely and evenly dispersed than other fossil fuels.
The top five coal producing countries are: China, US, India, Australia and South Africa. All these countries use their indigenous coal as the primary fuel for electricity generation and all except India have a sizeable coal export market.
The world currently consumes over 5500 million tones of coal for use in power generation, steel production, cement manufacture, as a chemical feedstock and as a liquid fuel (IEA, 2005a).
Where there is a forecast of depletion in the supply of oil and gas in next 50 years coal may serve the purpose for next 150 years or more and by then new and renewable sources of energy will find wide market.
Coal can be converted to liquid and gaseous fuels to substitute for oil and ultimately to less depend on imported oil -- South Africa has a well-established coal-to-liquids industry, and China is currently adopting this technology.
China wants to cut down its oil import dependence by building a commercial scale direct coal liquefaction plant in Inner Mongolia, which will produce around 50,000 barrels a day of finished gasoline and diesel fuel.
Overall costs for coal-based power stations are usually lower than from other sources and utilization of coal for electricity generation should be a key choice. At present almost 40 percent of global electricity generation is based on coal (IEA, 2005b). The generation technologies are well established.
Not only the developing nations but developed nations also face power crisis and the solutions for that has been recognized as utilisation of more coal in power plants.
Renewable energy can reduce dependency on finite energy sources and remove some of the risk on oil import dependence.
Hydropower provides many countries with a substantial amount of their electricity needs; however, when weather conditions deviate from normal, severe problems such as the blackouts experienced in Brazil and New Zealand can occur.
New Zealand's crises in 1998, 2001 and 2003 occurred as a result of an over dependency on a single energy source -- hydro power. There has been now a four-fold increase in coal fired electricity generation (IEA, 2005b).
In California due to severe energy crisis in 2000-2001 a 1300-mile transmission system to generate 12000 MW of electricity -- 6000 MW from coal fired gasification (IGCC) plants and 6000 MW from wind power -- has been in plan.
In September 2003 Italy suffered a nationwide blackout, which had an impact on its total population of 57 million people. Much of Italy's electricity is imported. The bulk of Italy's own generation is from oil-fired power stations.
Due to the increasing cost of oil and a need for new and diversified power generation, many of these stations are being converted to gas or coal fired plants. Enel, Italy's largest generator, aims to double its coal fired capacity to over 10,000 MW, or 50 percent of its generating portfolio. The Italian government has also eased regulations on building new power plants and sought to encourage greater investment in the electricity sector.
In Bangladesh the only commercial energy resource that mainly supports power generation in the country at present is natural gas. About 70 percent of power generation depends on natural gas.
As per the forecast of Petrobangla, the total remaining gas reserve would meet the country's projected energy demand upto 2015. So discovery of additional gas fields or alternative sources of fuel could meet up this challenge. Coal discoveries of the north-western part of the country, with its total estimated mineable reserves of 1400 Mt (which is approximately 37 Tcf of natural gas in terms of heat value) seemed to have solved this problem.
Considering that many countries in the world have between 40 percent to 60 percent of their electricity generation using coal, Government of Bangladesh should take prompt action for a rapid increase in generation of coal fired electricity, which will ultimately have the effect of enhancing the energy security of the country.
Future power plants in the country may be set up on dual fuel system using coal and gas for the sake of better energy security. This would save and conserve Bangladesh's reserve of natural gas, and prevent the dependence on oil import for power generation.
Coal production should be at such a rate that its availability in the country for a period of at least 50 years can be confirmed.
China, manufacture small-scale power plants in the range 3 to 5 MW operating on coal, and these technologies can also be promoted in our country for electricity supply in remote and rural areas.
It is important to understand the environmental impacts of mining, processing, and utilization of coal.
The choice of mining method is largely determined by the geology of the coal deposit. Underground mining currently accounts for about 60 percent of world coal production, although surface mining is more common in several important coal producing countries like in Australia where it accounts for about 80 percent, in the US 67 percent. In India also surface mining is given importance. Surface mining or opencast mining is only economic when coal seam is near the surface.
Opencast mines damage a large land surface area, displace people from their ancestral homesteads and cause agricultural losses. But the method is cost effective, recovery is high around 90 percent, comparatively better in safety aspects and is considered to be a modern method.
Surface mining requires large areas of land to be temporarily disturbed. This raises a number of environmental challenges, including soil erosion, dust, noise and water pollution, and impacts on local biodiversity. But modern technology considerably reduces these problems. The idea is to select proper technology.
Mine subsidence can be a problem with underground coal mining, whereby the ground level lowers as a result of coal having been mined beneath. Steps are taken in modern mining operations to minimise these impacts. Good planning and environmental management minimises the impact of mining on the environment and helps to preserve biodiversity. Computer simulations can be undertaken to model impacts on the local environment. The findings are then reviewed as part of the process leading to the award of a mining permit by the relevant government authorities.
Whether coal is to be extracted by Opencast or by Underground methods of mining the selected method is to acknowledge the need to reduce environmental impact and to provide security of supply, deliver environmental and social goals and promote competitive energy markets.
Environmental issues related to coal processing include water quality issues such as acidic drainage, slurry impoundment discharges, physical disturbances, and gob fires.
The environmental impacts of coal use, mostly for electric power, include harmful emissions and solid waste disposal. Emissions of concern include sulfur and nitrogen oxides that lead to acid rain; particulate matter that causes haze; mercury and its health impacts; and carbon dioxide as greenhouse gas and its potential to change climate.
Methane (CH4) is a gas formed as part of the process of coal formation. It is released from the coal seam during mining operations. Methane is a potent greenhouse gas. Methane from coal seams can be utilised rather than released to the atmosphere.
Dr. Rafiqul Islam is Professor, Dept. of Applied Chemistry & Chemical Technology, Dhaka University.
Articals of interest to the coal industry.