Cement, Energy and Environment July-Sep 2002

REDUCING POLLUTION FROM FOSSIL F{JEL The lfindu 2 1 February 2002 sTwo new clean-up techniques may help to reduce the pollution from burning fossil fuels. Chemists in Germany have used a green so lvent to remove sulphur fi·om diesel. while·biologists in the US have bred bacteria that gobble up coal contaminants. When oil and coal burn. su lphur contained in them fo rms the ac idic gas sulphur dioxide. This creates acid rain and corrodes fuel-burning equipment. Fossi l fuels are now treated with water to strip them o f sulphur (a catalyst combines hydrogen w ith the sulphur, producing H~S gas). But this can be expensive and leaves residual sulphur, so many povver stati ons still need to scrub their exhaust gases. Andreas Jess and co ll eagues at the Rheini sch– Westnische Technische removed sulphur from diesel. Their method iseco-friendly and removessome of the mos t reca lcitrant su l phur compounds. They use an ionic liquid. These liquids are salts that melt at temperatures below 100 °C. They do not give off noxious fumes and disso l ve many organi c compounds. .less and colleagues identifi ed ionic I iquids that react wit h th e su lphur-contain ing compounds in diesel,' but .not with the fuel itself. So when the two are mixed they separate like oil and water , while chem ical react ions draw the sulphur compounds from the diesel into the ionic liquid. On an industrial sca le, su lphur-l aden ionic liquid could be cleaned and recycled for subsequent extraction steps. The whole process could run at temperatures and pressures that are much lower than 1hose used for the traditional water treatment. Expos ing bacteria to such increas ingly harsh conditions. the duo identified strains that could survive at high press ure, acid ity, and concentrations of toxic metals and at temperatures up to 85 "C, while digesting coal slurry. NE\V TECH~OL()(;y DEVELOPF:D FOR CLF:ANI~G POWER PLANT Green Business Opportunities 2002 8(1): 18 A new technology that cleans the emissions from coal-fired power plants can perform the task more efficiently and cheaply than is now possible. Acco rding to the Ohio University sources, the technology i s an improvemen t ove r th e electro static precipitator that is curren1ly used for cleaning smoke– stacks emi ss i ons. T he current design uses steel pl ates to attract dust particles from the combustion gases before they can enter the environment. This fl y ash must be removed from the exhaust prior to release i nto the environment because of the contamina nts it carri es. On the other hand, the new technol ogy uses one to three millimeter thick membranes woven from carbon, sili con, and similar ti ber-based materials to capture the fine air pollutants and toxic heavy metals. Because of the materi als used in their manufacture, the ne\v membranes are not on ly mo re efficient than the steel plate type but less expensive, I 0 to 20 times lighter and not suscepti ble to corrosion. Although the main purpose of thi s technology is to red uce emi ssion from coal fired power plants, the technology could be used f or any industry that emits fine air pollutants or trace heavy metal s. Counesy : TIDE£. Mar. 2002. fp 99 . !()() & /01 Fax: 9 / 11./682/.f.f: E-mail: Olllreachro'leri.res. in ll'eh: 11'11'11' teriin.orR m