July 15, 2008

New strategies for conquering environmental challenges

Angela Neville, JD

CAIR’s effect on SCR operations

Another session dealt with the looming impact of the Clean Air Interstate Rule (CAIR) on the utility industry. Speaker Joseph Skipper, project manager with SCR-Tech, pointed out that CAIR will soon take effect and promises to have a dramatic effect on the selective catalytic reduction (SCR) systems that are used to reduce nitrogen oxides (NO_x) emissions. The annual NO_x emissions cap will be reduced by 52% and the ozone season cap will be cut by 45%, both from 2003 levels.

“In addition to reducing the emissions cap, CAIR also makes year-round SCR operation mandatory beginning in 2009,” Skipper said. “Currently, SCRs only have to be operated during the ozone season in most states. Year-round operation will drastically increase the burden placed on the catalyst and the overall SCR system.”

According to Skipper, each utility needs to develop a customized SCR management strategy. Year-round SCR operations could trigger a number of challenges, such as increased exposure to flyash and large particle ash. Another challenge is that the increased consumption of ammonia by the ammonia system due to year-round operation will mean additional site deliveries, the addition of storage capacity, and increased maintenance of the ammonia system. An additional concern is that the lead time for catalyst regeneration will increase, so prudent plant managers should have spare catalysts on hand. Skipper encourages utilities to plan now to ensure a smooth transition to year-round operation.