There are a number of methods for handling waste gases at upstream oil and gas facilities, the most common being combustion. Flaring and incineration are two methods of combustion considered acceptable by the Alberta Energy Regulator (AER). Historically, the most common type of combustion has been flaring. In recent years, incineration technology has emerged as another method of combusting waste gases. This EnerFAQs explains why flaring and incineration are sometimes necessary and how the AER ensures that flaring and incineration are carried out in a manner protective of public safety and the environment.
Flaring and incineration are two technologies used to combust waste gases that are unable to be processed or sold.
The type of emissions depend on the composition of gas and the combustion efficiency. For example, high efficiency combustion ensures that nearly all methane is converted to carbon dioxide (CO2) and water vapour. If hydrogen sulphide (H2S) is included in the waste gas stream, nearly all of the hydrogen sulphide is converted to sulphur dioxide (SO2).
If the waste gas stream contains both methane and H2S, a lower combustion efficiency flare or incinerator may emit some H2S and methane as unburned products. Lower combustion efficiency can also result in other emissions, including black smoke and particulates. The minimum combustion temperature, liquid separation and minimum heating value of the waste gas stream in AER regulations ensure that components in the waste gas, including methane and H2S, are adequately combusted.
Flaring and incineration are two different technologies used to combust natural gas waste. Emissions depend on factors such as combustion efficiency and heating value of the gas being combusted. Generally, the higher the combustion efficiency and heating value, the lower the impact on the environment.
Many factors can affect combustion efficiency. For example, a flare stack exposed to windy conditions may perform at a lower efficiency than a stack that operates in calm conditions. However, due to their height, flare stacks often better disperse emissions into the atmosphere in hilly or mountainous terrain than do incinerators. Meanwhile, incinerators are not affected by windy conditions. A correctly operated incinerator can yield higher efficiencies through proper mixing, gas composition, retention time, and combustion temperature.
Properly designed incinerators can result in higher combustion efficiency than flares. However, incinerators can be affected by a narrow range of flow rates compared to flares and therefore have difficulty adequately dispersing emissions with higher H2S concentrations in the waste gas. It is important to select the combustion technology suitable for the particular application.
Combustion efficiency, generally expressed as a percentage, is essentially the amount of methane converted to CO2, or H2S converted to SO2. The more converted, the better the efficiency. Combustion efficiency can be affected by many factors, including meteorological conditions, operator competency, and waste gas composition.
For flares, the AER requires the minimum energy content of the gas mixture (20 megajoules per cubic metre), which has been shown to result in higher combustion efficiencies. If a waste gas stream contains low amounts of hydrocarbons, fuel gas must be added to allow the mixture to combust efficiently.
To ensure combustion efficiency for incinerators, the AER requires that the stack top temperature is maintained at least 600 degrees Celsius or higher and have a minimum residence time (the time the gas remains within the incinerator before being released into the atmosphere) of 0.5 seconds. Conventional incinerators are equipped with refractory lining—which help contain most of the combustion heat and control the combustion airflow into the incinerator—can increase combustion efficiency. Some incinerators have innovative hybrid designs that do not contain refractory lining. Properly designed incinerators can achieve very high combustion efficiency.
The AER requires that all waste gas combustion technologies, including those for SO2, be designed to comply with Alberta Environment and Sustainable Resource Development’s Alberta Ambient Air Quality Objectives and Guidelines.
The Government of Alberta has set out acceptable minimal levels of safety and environmental protection related to air quality. These are called the Alberta Ambient Air Quality Objectives and Guidelines and are among the most stringent in Canada.
The AER regulates flaring and incineration through performance and reporting requirements, permits, and data collection, as detailed in Directive 060: Upstream Petroleum Industry Flaring, Incinerating, and Venting.
A permit is required for well test flaring or incineration when the waste gas contains more than 5 per cent H2S or the total well test volume exceeds 200, 400, or 600 thousand cubic metres, depending on the type of the well.
The AER requires that companies evaluate flaring and incineration at existing facilities and determine if the gas should be conserved. The licensee or operator is expected to consider the following:
Before planned flaring or incineration (unlike flaring or incineration during an emergency), the licensee or operator is required to provide 24-hour advance notice to the appropriate AER field centre, all residents within a 3 kilometre (km) radius for well tests with an H2S content greater than 1 per cent, and all residents within a 1.5 km radius for well tests with an H2S content of less than 1 per cent.
Additional “good neighbour” notification, including notice for short-duration events, should be conducted if members of the public have identified themselves as sensitive to emissions from the facility or if they are interested in receiving notice of planned flaring or incineration for other reasons.
The AER expects the licensee or operatorto provide an information package to the public before planned flaring or incineration. The information package must include
The AER expects the licensee or operator to address any concerns raised by the public before flaring or incinerating. If, after reasonable attempts, outstanding concerns remain unresolved, the operator or the public may request the assistance of the appropriate AER field centre.
In situations where a flaring or incineration permit is required or where an application has been made for such a permit but your concerns have not been addressed by the licensee or operator, you may submit a statement of concern to the AER. The AER will consider the statement of concern. See EnerFAQs Expressing Your Concerns – How to File a Statement of Concern About an Energy Resource Project.
In situations where a flaring or incineration permit is not required and your concerns have not been addressed by the licensee or operator, you may contact the appropriate AER field centre. AER staff will then respond to the inquiry according to established procedures. If the licensee or operator is in compliance with the requirements in Directive 060 and has appropriately considered any unique circumstances related to the flaring or incineration and if field centre staff have determined that all procedures for the planned event are acceptable, it will be allowed to proceed.
For more information on the AER and its processes or if you wish to speak with your local field centre or have general questions about oil and gas in the province of Alberta, contact the AER’s Customer Contact Centre: Monday to Friday (8:00 a.m. to 4:30 p.m.) at 1-855-297-8311 (toll free).
This document is part of the EnerFAQs series, which explains the AER’s regulations and processes as they relate to specific energy issues. Please visit www.aer.ca to read more of the EnerFAQs series.
Every year the AER collects, compiles, and publishes a large amount of technical data and information about Alberta’s energy development and resources for use by both industry and the general public. This includes raw data, statistics, hearing materials, and information on regulations, policies, and decisions.
Publications may be either viewed at the AER library or obtained from the Information Distribution Services (IDS). Both are housed on the tenth floor of the AER head office in Calgary. Publications may also be downloaded free of charge from the AER website (www.aer.ca).
To obtain a print or CD copy of a specific publication, contact IDS by phone (403-297-8311), fax (403-297-7040), or e-mail (InformationRequest@aer.ca).AER Head Office