According to the US Department of Energy, the 400MW Texas Clean Energy project will be the cleanest coal-fueled power plant in the world when it is completed in 2015.

The plant will use an integrated gasification combined cycle that emits less than 10% of the carbon dioxide emitted by a similarly sized conventional coal-fired power station and less than a quarter of the emissions of a gas-fired plant.

As well as capturing 90% of CO2 produced, it will also capture 99% of sulfur dioxide, 90% of nitrogen oxide and 99% of mercury.

Rather than burning coal, the gasification bakes it in an airtight chamber that allows only controlled amounts of oxygen to enter.

Hydrogen and carbon monoxide gases squeezed from the coal as it bakes are then processed into synthetic gas, or syngas.

Water vapor is then added to the syngas, converting the carbon monoxide to hydrogen and carbon dioxide.

“The gas is then cleaned of impurities, and separated into pure streams of hydrogen and carbon dioxide,” the DOE said.

“The hydrogen powers an advanced turbine to generate electricity and its carbon-free exhaust heats water to generate steam that’s fed to a turbine to produce even more electricity.

“Of the nearly 2.9 million metric tons of carbon dioxide to be captured annually at the Texas plant, 83 per cent will be used in the West Texas Permian Basin for enhanced oil recovery – a technique where carbon dioxide is pumped into a known reservoir where it expands and forces the oil out of the well.

“The rest of the captured carbon dioxide will go to producing urea – a valuable compound with many industrial applications.”