Focus on Coal 


the CCS portion of the capital investment until it is justified by market and policy conditions. Gasification is a manufacturing process that


converts any material containing carbon, including coal, into synthesis gas (also known as syngas). Te syngas can be burned to produce electricity. Research is being conducted on Integrated


Gasification Combined-Cycle (IGCC) systems, in which the syngas is burned as fuel in a combustion turbine, which drives an electric generator. Exhaust heat from the combustion turbine is recovered and used to boil water, creating steam for a steam turbine- generator.


Te use of these two types of turbines together (combined cycle) is one reason why gasification-based power systems can achieve high power generation efficiencies. Research suggests that future IGCC systems may achieve efficiencies approaching 45 per cent, and the goal is to achieve efficiencies as high as 60 per cent. By comparison, a conventional coal-based boiler plant that uses only a steam turbine-generator is typically limited to efficiencies of 33–40 per cent, although it may achieve 45 per cent or better under some conditions. Higher efficiencies mean that less fuel is used to generate the rated power, resulting in lower costs and the formation of fewer greenhouse gases. For example, a 60 percent-efficient gasification power plant could cut the formation of carbon dioxide by 40 per cent, compared to a typical coal combustion plant. Carbon capture and storage (CCS) means separation and capture of CO2


from fossil fuel-fired


power plants and the recovery of a concentrated stream of that CO2


that can be transported by pipeline and


stored, in either an underground formation, or the sea bed. Most research efforts are focused on systems for capturing CO2


from coal-fired power plants because


they are the largest stationary sources of CO2 CCS technologies include post-combustion


. (captures CO2 from power plant flue gases), pre-


combustion (widely used in fertilizer manufacturing and in hydrogen production without any CCS) and oxy-fuel combustion (still in the demonstration phase, but showing great potential because recycling the flue gas through the boiler concentrates the CO2 the flue gas, making it easier to separate the CO2


level in .)


According to the DOE’s National Energy


Technology Laboratory: “CCS technologies, if commercialized and widely deployed, would allow us to continue using fossil fuels in tandem with the existing energy infrastructure … As we continue to use current fossil energy sources for years to come, we need ways to control CO2


emissions for the energy


systems we’re using … By attacking the problem from several fronts – energy conservation, expanded use of renewables, as well as CO2 CO2


capture and sequestration, on existing and new


systems – we have the best chance at reducing GHGs while maintaining a strong economy, which requires energy at a reasonable cost.” Despite the many commendable efforts taking place


to develop sustainable forms of power generation, coal and other solid fuels are likely to remain an essential part of the nation’s energy picture for many years to come. As one of the nation’s lowest-cost electric power sources for the foreseeable future, coal will remain a necessary and important part of US energy production. Te nation is turning to clean coal technologies as a way of making use of this abundant and available resource in the most environmentally responsible way possible. New coal technology promises to balance environmental and economical concerns, while continuing to satisfy our growing world with energy output. l


Robert S Giglio is the Director of Global Marketing and Strategy for the Foster Wheeler Global Power Group. www.fwc.com/globalpowergroup


Toxic and


flammable gas detectors


T have been used to monitor CH4


he STX3241 and STX3261 toxic and flammable gas detectors and TX5920 Vortex Air Flow Sensors, from Trolex, , CO and air


flow at the Svea Nord mine in Norway. The sensors have a high strength moulded housing sealed against dust and moisture to IP65 standard and EMC protection, making the systems resilient in the extreme, arduous conditions in the mine.


42 www.engineerlive.com All the sensors have ATEX M1 approval, a


legal requirement which identifies equipment that continues to operate when a potentially explosive atmosphere is present, says Trolex. The STX3261 flammable gas sensor is a


robust, dust and waterproof pre-calibrated gas detector which utilises a poison resistant catalytic combustion sensor to monitor flammable gases present in the atmosphere such as methane and propane. The large mass of the sensing element


assures a long and reliable operating life with exceptional stability even in conditions of high vibration. The sensor has a life expectancy of about


five years depending on the monitoring conditions and can be rapidly serviced or replaced at the end of its operating life. It is also available with a remote mounted gas- sensing module for installations where space or access is restricted. The STX3241 toxic gas sensor is designed


for ease of installation and maintenance in arduous, exposed locations providing economical safety protection from toxic gases such as carbon monoxide, hydrogen sulphide, nitrogen dioxide, nitric oxide and sulphur dioxide in mining and tunnelling applications. l


For more information, visit www.tolex.com emission controls including


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