Coal is one of the world’s most important and abundant fossil fuels and is a major competing energy source in the world market. In 1996 it accounted for 27% of the world’s traded energy, about 20% in the UK and Europe, but higher in some countries, notably China (76%). Future projections show it will have a significant part to play for many decades.
In many countries coal is used primarily to generate electricity and it accounts for 40% of the world’s electricity generation.
Sufficient reserves of coal are available for 200 to 1,000 years. These are distributed all over the world and are easily transported. But there are environmental problems.
For electricity production and all heating applications, natural gas is now the preferred fuel in the UK. This has been driven by the environmental advantages of natural gas over coal in meeting tighter emission standards, and economic advantages, including the efficiency of combined cycle technology of nearly 55%.
The link of the North Sea gas fields to the wider Continental European grid, massive growth in gas consumption in central Europe and the pressure from Far East consumers mean that within the next decade gas prices will inevitably rise. The major and uncertain role of the former Soviet Union as well as the Middle East is also a key factor.
The UK Technology Foresight Energy Panel supported nine high-priority opportunities for UK energy products and services including clean-coal power generation. A panel was set up to examine clean-coal generation. It concluded that:
There is a world-wide market for clean coal power plant. The demand for electricity is expected to increase by 2 3% a year for the next 15 years more rapidly in developing countries. Analysis indicates coal-fired power stations are likely to have a big share of this market, amounting to £500bn over the next 15 years, almost 70% of it in Asia.
There is a strong UK industry background: clean coal technology (CCT) is suitable to minimise the environmental impact of coal use. Legislation is moving toward lower emission limits for power plant. Where lower limits are introduced, only CCT power plants will be acceptable.
The UK has a strong CCT technology base in industry and academia, and UK power-plant equipment manufacturers have a world class reputation for clean coal power generation components. The size of the UK’s power engineering sector is large and comparable with that of the aerospace sector.
Future demands of the market dictate the technology targets for advanced clean coal plant. It must be cleaner and have a lower through life cost than conventional subcritical pulverised fuel steam plant with low NOx burners and flue gas desulphurisation. The cost of super-critical plant is nearly that of sub-critical plant, but other types, such as air-blown gasification cycle and integrated gasification combine cycle, have some way to go.
A technology development programme is required. Those represented by coal science have a big role to play, especially those concerned with coal combustion and gasification, and pollutant prevention.
We need a better understanding of coal structure, and of the chemistry of the combustion of blended coals. More sophisticated laboratory techniques, especially at high pressure, can provide more detailed knowledge of the combustion and gasification processes. These can be combined with computational fluid dynamic analysis to give better techniques for the design of equipment for pulverised coal combustion and for gasification and for prediction of the pollutants formed.
Better and cheaper gasification can lead to a low CO2 emission economy. If the CO2 is removed from the flue gases and stored or used for gas and oil well injection, the climate change problem can be reduced for a number of years.
Professor Williams is Livesey professor and head of the Fuel and Energy Department, University of Leeds. Edited from The 1997 Robens Coal Science Lecture, given on Monday this week, to the British Coal Utilisation Research Association.