A new federal air quality rule from the United States Environmental Protection Agency (EPA), 40 CFR Part 60 Subpart OOOO, could affect on how the oil and gas industry handles waste gas emissions.
Facing the prospect of tougher regulations, the agency is seeking ways to turn the challenges into positives. Vent gas management has become more important for companies learning how to operate under the new rule.
At a presentation hosted by the SPE Gulf Coast Section’s Health, Safety, and Environment study group, Jeff Voorhis, a business development and regulatory specialist at Hy-Bon Engineering, and Audrey Mascarenhas, the president and CEO of Questor Technology, discussed new approaches for companies.
Commonly referred to as EPA Subpart Quad O, the rule states that a single storage vessel in oil and gas production, natural gas processing, or natural gas transmission and storage with the potential of producing 6 tons/year or more of volatile organic compound (VOC) emissions must reduce the amount by 95%. The EPA does not stipulate a way to meet the requirement.
One method of compliance is by vapor recovery, which was the primary focus of Voorhis’ presentation (Fig. 1). Hy-Bon specializes in the production of vapor recovery units (VRUs) designed to comply with regulatory standards by eliminating the emission of stock-tank vapors into the atmosphere. These units capture diverse gas streams, including methane, carbon dioxide, and hydrogen sulfide.
VRUs have several benefits, Voorhis said. They can capture up to 100% of the hydrocarbon vapors that accumulate in tanks. The recovered vapors have a higher Btu content than pipeline-quality natural gas and can have more market value than methane alone. The recovery can reduce regulatory and liability exposure.
Voorhis said that companies can make money from the emissions that they have to control anyway.
“The mantra to have is what gets seen by companies, by yourself, and by agencies gets measured; what gets measured, gets controlled; and the good news is … what gets controlled, can make you money,” he said. “You can become a profit center at your companies now.”
The value, however, depends on the Btu content of the gas and the way in which the gas is used. On-site fuel is measured in terms of fuel that must be purchased. Gas coming through a pipeline is measured by the higher price for rich gas. Gas from a processing plant is measured by the sale of natural gas liquids and methane, which can be separated, Voorhis said.
Mascarenhas’ presentation focused on the general environment fostered by tighter EPA regulations, such as Quad O or other regulations that set new performance standards for sulfur dioxide, hazardous air pollutants, and fugitive emissions from compressors. Like Voorhis, Mascarenhas said there is potential for a win-win situation in which regulations are met and companies can generate profit.
The combustion of hydrocarbons is the center of this opportunity, as inefficient combustion leads to an increase in VOCs, as well as an increase in greenhouse gases because the global warming potential of methane is 21 times that of carbon dioxide.
Mascarenhas said that clean combustion can be measured independently and consistently at 99.99% and is auditable for regulatory compliance. It is cost-effective, low maintenance, and provides an air-quality benefit.
The capture by clean combustion of the excess energy being “lost” in waste gas offers an avenue for profit, Mascarenhas said.
“I think there’s a great opportunity on the combustion side, especially if you can do clean combustion because there’s this enormous opportunity to use the heat wisely,” she said. “I think it makes business sense, not just in terms of dollars and cents.”
The heat from clean combustion of typically flared gas at 99.99% efficiency has many uses, Mascarenhas said. The recovered heat can help with water vaporization, steam generation, and can serve as an alternative to diesel generators, which would further reduce emissions on wellsites. The heat from waste gas can also be used for hydrate prevention and for heating up oil and water. This helps in fracturing operations, where water must be hot. Mascarenhas said much waste heat is available: A well generating 5 Mscf/D of waste gas could generate 220 million Btu/hr of waste heat.