Below, the technology behind the efficient coal wedge is explained by Bob van der Zwann, and how this might feature in reducing carbon emissions. There is a strong argument that efficiencies in fossil fuel generating facilities should not be sought, rather they should simply be replaced by non polluting sources. It is unfortunate that coal fired electricity is likely to dominate global production for a number of years to come. Developing and deploying cleaner coal plants appears an appropriate approach in reducing carbon dioxide to double that of pre-industrial levels, and a transitional technology when aiming towards zero carbon emissions in electricity generation.

“While today coal power plants operate on average at 35% efficiency (largely because the current fleet consists mostly of older subcritical units), the state-of-the-art pulverised coal power plant (based on supercritical or ultra-supercritical technology) has a generating efficiency of typically 45% (for hard coal or lignite).

Continued improvements in high-strength alloys are being researched and implemented that allow for higher steam temperatures and pressures. Since higher steam temperatures correspond to higher efficiencies, efficiency gains are continuously being achieved. It is expected that advanced and improved alloys for boilers, turbines and piping will continue to become available over the decades to come, such that efficiencies may eventually reach values as high as some 55% (Lako, 2004).

IGCC [Integrated Gasification Combined Cycle] plants today achieve up to 40% efficiency, and may soon have efficiencies of some 45-50%. Continued R&D will make gas turbines and combined cycles increasingly efficient, and it estimated that IGCC technology may remain up to 5% more efficient than the most advanced PC technologies, so that in the long run IGCC efficiencies may become as high as 60%. Gains in efficiency result in a more effective resource use, but also, for example, in less carbon dioxide, sulphur dioxide, nitrous oxides, mercury and particulate matter emitted per kWh of electricity produced. These efficiency gains can therefore be considered as an opportunity for innovative clean(er) coal technology Employment." (Bob van der Zwaan, 2004, Coal and Climate Change, ECN, Policy Studies Department, Amsterdam, the Netherlands Harvard University, John F. Kennedy School of Government, Cambridge MA, USA)

Ultimately, the so called efficient coal wedge must be replaced by a wedge that does not emit carbon dioxide.