Fossil fuel-fired power generation

Many coal-fired units all over the world currently operate at efficiencies well below 30%. “This is a significant waste of energy and unnecessary cause of climate-damaging CO₂ emissions. Given that the share of coal in power generation is rising, this is alarming,” said Nobuo Tanaka, Executive Director of the International Energy Agency (IEA). “Particularly,” Mr. Tanaka added, “since coal-fired power generation technologies with efficiencies close to 45% are already operating in certain locations. We must make increasing the efficiency of new fossil fuel power plants a priority, above all in major coal-using countries.”

The new IEA publication Fossil Fuel-Fired Power Generation: Case studies of recently constructed coal and gas-fired power plants highlights these challenges. The study responds to a request from the Group of Eight summit in 2005, asking the IEA to illustrate the efficiency achieved in modern plants in different parts of the world using various types and grades of fossil fuels. The plants were selected from various geographical areas, because local factors influence attainable efficiency. In a series of case studies, the IEA assessed which are the most cost-effective and have the highest efficiencies and the lowest emissions. These include pulverised coal combustion (PCC) with both subcritical and supercritical (the latter involving very high steam pressure and temperature) cycles, a natural gas-fired combined cycle plant, and a review of current and future applications of coal-fuelled integrated gasification combined cycle (IGCC) plants.

Efficiency – what is attainable now and in the future?
The report shows that technologies with high efficiency and very low conventional pollutant emissions are available now at acceptable cost for a wide variety of fuel types. Depending on the quality of coal and the geographic location, modern coal-fired technologies exist that operate from about 35% to close to 45% efficiency. Efficiencies approaching 50% (higher heating value basis) are envisaged within the next 10 to 15 years, as development of very high temperature steam conditions are continued.

Natural gas-fired combined cycle units are more efficient at over 50% now, less expensive and quicker to build than coal-based systems. Advanced developments in natural gas-fired turbines will increase efficiencies of these systems even more, maintaining their strong presence for new power projects. Developments in gas turbines will also benefit commercial offerings for coal-based IGCC with efficiency approaching 50%. With IGCC now available as a commercial package, orders are likely to follow, but probably must be aided at first by market entry incentives.

Proper policies are crucial
“The challenge to the policy makers now is to formulate measures that would enable wider deployment of these technologies globally, but particularly in countries where demand is growing at the highest rates, while also promoting technological development towards even higher efficiency. This new study is an important steppingstone in this direction,” said Mr. Tanaka.