Environmental GRI Performance Indicators
EN20 – NO, SO, and other significant air emissions
Our Impacts
The major air emissions released by Enbridge facilities include methane, carbon monoxide, nitrogen oxides (NOx) and volatile organic compounds (VOCs). Other contaminants released, but in much smaller quantities, include sulphur dioxide (SO2), hydrogen sulphide and particulate matter.
We work to keep air emissions from our operations below regulated limits. In some cases, we have exceeded regulatory requirements and have installed environmentally friendly technologies in our facilities that reduce air contaminant emissions.
The largest source of emissions from our Liquids Pipelines operations is from tank storage. A rigorous maintenance program includes regular inspections of emission control devices and repair or replacement of them to ensure they meet regulatory criteria.
In large urban centres, such as the Greater Toronto Area, we also take an active role in promoting cleaner fuels and vehicles. For more information, please see the ‘Transport’ section in this report.
Our Performance
Reporting Criteria Air Contaminants
Criteria air contaminants are a group of common air pollutants released from sources, including incineration, industrial production, fuel combustion and transportation vehicles. We have established programs setting our roles, responsibilities and timelines for reporting our criteria air contaminant emissions to various government agencies in Canada and the U.S.
In Canada, Enbridge Gas Distribution and Liquids Pipelines track and report annual criteria air contaminant emissions under the National Pollutant Release Inventory. The air contaminants covered under the regulation include NOx, SO2, VOCs, carbon monoxide and particulate matter.
In the U.S., we track and report to the Environmental Protection Agency’s Toxic Release Inventory and to state regulators on VOC emissions for liquids pipeline terminals; and NOx, SO2, particulate matter, and carbon monoxide emissions for our natural gas system.
Managing Emissions from Gas Plants
Our Gas Transportation business is continually looking for opportunities to upgrade its gas facilities and pipelines in ways that contribute to operating, environmental and safety goals. One example is acid gas injection, which uses advanced technology to compress acid gas, primarily hydrogen sulphide and carbon dioxide, and inject the gases into suitable underground reservoirs, thereby avoiding emissions to the atmosphere.
Our first acid gas injection plant, which opened in 2004 in Wayne County, Mississippi, cut sulphur dioxide emissions by about 230 tonnes in 2007 compared with a traditional treating plant. The facility also injected 3,110 tonnes of carbon dioxide that would have otherwise been released to the atmosphere. We opened our second acid gas injection well near the Aker Treating Plant in 2006. In 2007 the facility injected 27,000 tonnes of carbon dioxide and avoided 174 tonnes of sulphur dioxide that would have resulted from a traditional gas treating facility.