Cleaner coal technology has reached a crossroads.

Cleaner coal technology has reached a crossroads.

It appears to be full steam ahead for the incumbent cleaner coal technology, the supercritical steam engine. Siemens and

India

’s Bharat Heavy Electricals Ltd have just announced a joint venture to develop coal-fired power plants using Siemen’s supercritical steam engine technology. Rapidly populating large coal generating countries like

China

and

India

, supercritical steam engines operate at 45% electrical efficiency, versus 36% for conventional steam engines, while realizing a 20% reduction in emissions. The addition of biomass can reduce emissions by another 20%. Over 400 supercritical plants are in operation worldwide.   

In developing countries such as the

US

, however, state agencies to coal miners are demanding that investments be made in cleaner burning IGCC plants. The Integrated Coal Gasification Combined Cycle Plant (IGCC) converts coal to a syngas to power a turbine, while CO2 is sequestered.

With hundreds of gigawatts in new coal generation planned, should the developing world also be installing the “cleanest” coal technology?  The developing world’s burgeoning electricity demands would have to wait until the advanced clean coal IGCC technology is commercialized, around 2010. It does give the incumbent supercritical steam engine a few more years to catch up on emission reductions. According to the International Energy Agency, both the advanced ultra coal steam cycled and the IGCC plants have the potential to capture carbon dioxide at an 85% efficiency level.

Next generation ultra-supercritical plants will operate at 55% electrical efficiency by reaching operating temperatures of 700°C. The World Bank calculates that for every one percent in electrical efficiency gains there is a corresponding 2% reduction in specific emissions and particulates.  The first generation IGCC clean coal plant is expected to operate at 45-50% electrical conversion efficiency, with no CO2 emissions. A few decades out, it is estimated that IGCC-SOFC plants that use hydrogen to fuel a high efficiency solid oxide fuel will reach 70 percent efficiency.

Both power plant models are placing their money on the same technology to achieve these efficiency gains: superalloys that can provide high performance at temperatures of 700°C and higher.  Sales in these high margin metals are increasing faster than the price of oil. 

Lien: EcoLog :: Will the Steam Engine Chug Along in the Era of Clean Coal?.