Absolute emission levels for greenhouse gases (GHG), SO2, NOx and particulate matter decreased compared to 2008. While we are pleased with this result, the reductions are not as sustainable as we would like, because they are primarily related to external conditions such as:
- fluctuating power demands from customers in a dampened economy
- unplanned outages and an accelerated major maintenance plan leading to lower combustion efficiencies
Total volumes of GHG emissions were lower in 2009 than 2008 by 3.2 million tonnes carbon dioxide equivalent (CO2e) due to lower production levels.
Due to these factors and the sale of natural gas assets in 2008, emission intensities increased. Additionally, the Canadian Hydro Developers’ assets acquired in November 2009 have not been included in this year’s intensity calculations but will be in subsequent reports, which will result in lower emissions intensity rates.
In 2009, all continuous emission monitoring systems (CEMS) at Centralia were replaced or refurbished due to concerns with accuracy and system characteristics.
Mercury regulations were introduced in Alberta in 2006 that mandate at least 70 per cent of mercury emissions must be removed. By January 1, 2011 mercury controls will be required at all of TransAlta’s coal-fired units in Alberta, plus those at which we have an operating interest.
From 2006 through 2009, TransAlta conducted mercury control tests at Alberta facilities that involved the injection of sorbent-activated carbon. The tests showed that the location to install the equipment must vary by plant so that the technology meets the 70 per cent capture threshold. The solution will cost $30 million with most costs passed through to power purchase agreement (PPA) customers.
Washington: mercury and nitrogen oxides
In March 2009, a proposed agreement between TransAlta and the Washington Department of Ecology was announced, regarding a significant step forward in improving air quality in Washington State. Key to the agreement is TransAlta’s willingness to voluntarily reduce mercury emissions by 50 per cent by 2012 to address air quality concerns in the region. Capture testing took place in 2009 and an activated injection product was selected. The process will cost US$20 to $30 million over the next several years. Additionally, continuous emissions monitoring systems (CEMS) for mercury measurement was certified by the Energy & Environmental Research Center (EERC). Currently, neither Washington State nor the U.S. federal government has regulations in place for mercury emission reductions.
As part of the same agreement between TransAlta and the Washington Department of Ecology, TransAlta agreed to reduce emissions of nitrogen oxide (NOx) by 20 percent beginning in 2009. This is two to five years earlier than TransAlta would have been required to reduce NOx emissions if an agreement had not been reached with the Department of Ecology.
As of October 30, 2009, TransAlta’s NOx 30-day rolling average for both Centralia units is 0.240 lb/mmBTU, compared to our previous limit of 0.300 lb/mmBTU annual average for both units. Centralia has committed to further continuous improvement efforts to reduce NOx by 2018. These reductions will take us below the federally required best available retrofit technology (BART) standard for Centralia.
Biomass exceedences addressed
TransAlta’s biomass facility in Grande Prairie, Alberta, part of the Canadian Hydro Developers acquisition in November 2009, had multiple operating permit exceedences in 2008 and 2009, including carbon monoxide (CO), NOx and opacity. Additionally, the surrounding community had registered complaints about black smoke. The Alberta Department of Environment levied a fine of $12,000. Site staff was brought together to help find solutions to the operational problems and, as a result, all issues have been addressed. Alberta Environment is now using this situation as a case study in fast resolution of environmental issues.
In Centralia, a three-year project to remove 41 transformers was completed in 2009. The transformers were causing poor precipitator performance, leading to several thousand megawatt-hour losses because of opacity derates. Opacity is an indirect measure of how much solid particulate is passing out of precipitators. Since the completion of the project there have been no opacity derates and opacity levels are less than one third of permitted limits.
The removed transformers also contained more than 500 parts per million polychlorinated biphenyls (PCBs). Their removal eliminates the risk of spills as well as time required for regulatory oversight.