Review assesses technology options for reducing mercury from coal-fired plants
In support of the proposed Canada-wide Standard (CWS) for mercury from coal-fired power plants (ELW July 4, 2005), the Canadian Council of Ministers of Environment (CCME) has released a background report titled Technical Review of Mercury Technology Options for Canadian Utilities.
Prepared by the Energy and Environmental Research Center (EERC), an affiliate of the University of North
Dakota, the report presents the results of a review and evaluation of nearly 100 different potential mercury control technologies or approaches, with a focus on the applicability to Canadian coal-fired electric power generation facilities.
The criteria used to evaluate the technologies included:
* applicability (based on coal type, plant design, quantity and form of mercury being emitted, and level of control required);
* technology effectiveness (in terms of percentage of mercury removed);
* technology cost (both capital and operating);
* commercial maturity (i.e. readiness);
* multipollutant capability (i.e. the ability of the technology to control multiple pollutants simultaneously);
* balance-of-plant issues (i.e. the impact of the technology on upstream and downstream equipment and processes); and
* environmental and technological implementation issues.
The evaluations were further based on three CCME guidelines: the potential of the technology to reduce mercury emissions by 50% or more; actual commercial availability of the technology (or potential availability by 2009); and other technologies that might be commercially available by 2015 and could potentially reduce mercury emissions by 50-90%.
The technologies examined were grouped into four main categories:
1. commercially available technologies (i.e. by 2009-the report notes that full-scale demonstration of mercury control technologies has not been carried out at any of the facilities included in the review);
2. commercially emerging technologies (scheduled for full-scale demonstration within the next one to three years, some of these may be available by 2009);
3. developing technologies (limited bench- or pilot-scale tests indicate high mercury removal potential, but availability is unlikely until after 2010); and
4. new generation plant technologies (applicable for new generation plants during construction).
In a series of charts, the report illustrates promising technology options for individual coal-fired power plants in Alberta, Saskatchewan, Manitoba, New Brunswick and Nova Scotia. In general, it concludes that only five technologies may prove to be commercially available within the next several years with the capability to reduce mercury emissions by more than 50%. These include: fuel switching; conventional coal cleaning; activated carbon injection (ACI); ACI injected upstream of a newly-installed fabric filter; and scrubbers.
Other promising technologies are on the horizon, among them as halogenated sorbents, sorbent enhancement additives (SEAs), combustion modifications, oxidation technologies, coal pre-treatment technologies and advanced particulate and scrubber technologies. These, however, may take longer to demonstrate, but should be considered depending on commercial deployment timelines, adds the report.
The review is available on the CCME Web site, www.ccme.ca.