Turning China's Greenhouse Gas into Clean Energy
While carbon dioxide shoulders the blame as the greenhouse gas most responsible for climate change, its less-talked-about cousin methane is also quietly warming the planet.
Methane is 23 times more potent than carbon dioxide (CO2) at trapping heat. However, it lingers in the atmosphere for only 12 years, while CO2 hangs around for a century.
“Since the level of methane in the atmosphere adjusts relatively quickly, we can mitigate global warming in the near term by reducing methane emissions,” said Mike Gallaher, director of RTI’s Technology, Energy, and Environment program.
That’s not all. “Methane is a primary component of natural gas, so by cutting emissions and recovering that methane we are capturing a source of clean energy,” Gallaher said.
Through a multi-country initiative, RTI is helping oil and natural gas industries in China to use proven technologies for recovering methane before it is lost into the atmosphere.
Methane to Market
China and the United States are ranked first and third, respectively, among the world’s emitters of methane, according to the U.S. Environmental Protection Agency (EPA).
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| Methane’s journey, from extraction to delivery as a fuel. Methane can be recovered at all of these points. |
However, they are working together under the EPA’s Methane to Markets Partnership to recover and use their methane emissions to mitigate global warming, strengthen energy security, enhance economic growth, and improve environmental health and safety.
The partnership was founded in 2004 by 14 countries that account for 60% of global methane emissions. It promotes methane recovery from four main sources: agriculture, coal mines, landfills, and oil and gas systems.
Through a grant from the Methane to Markets program, RTI is collaborating with the China University of Petroleum (CUP) in Huadong to help China’s oil and gas industries detect and recover methane leaked during production, processing, transmission, and distribution of these fuels.
“China’s oil and gas industries are relatively modern,” said Gallaher, who directs RTI’s work with CUP. “But there are still great opportunities for improved methane recovery, primarily around equipment maintenance.”
Proven Ways to Stop Leaks
In December 2008, RTI and CUP co-authored a peer-reviewed study of the potential to apply international best practices in methane leak detection and reduction in China. They analyzed more than 80 technologies and practices recommended by U.S. oil and gas industry partners through the EPA’s Natural Gas STAR program and ranked them according to the magnitude of emission reduction potential, availability of equipment and skilled labor, and cost effectiveness.
“We conducted a cost-benefit analysis to recommend those technologies and practices that make the most economic sense for China based on equipment and labor costs for the corresponding level of reduced emissions,” said Jeff Coburn, an RTI senior research chemical engineer who contributed to the study.
Based on this analysis and interviews with Chinese oil and gas field managers, RTI and CUP recommended five priority technologies or practices for each industry sector: production, processing, transmission, and distribution.
In production, for example, the study recommended retrofitting oil storage tanks with equipment to capture methane vapor. Raw gas is often found with oil in the same underground formations. The crude oil and gas are pumped through pressurized pipelines into unpressurized storage tanks, where methane that was dissolved in the oil vaporizes and gets leaked or vented into the air.
“By installing vapor recovery units, oil and gas companies can capture this methane and process it into natural gas,” Coburn said.
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| During the processing of oil and natural gas, methane leaks out from refinery equipment that is corroded or poorly installed. Directly inspecting the equipment with leak detection devices can help engineers identify and repair the worst leaks. |
In the refining process, unintended leaks from valves, connections, and other components can develop over time due to pressure, corrosion, and other causes. The same risks of leakage apply in the transmission of natural gas to city regulators and propane plants and subsequent distribution to consumers. “Many small leaks amount to significant methane losses,” said Gallaher.
Detecting these odorless and invisible methane leaks is the first step to repairing them. Current practice in China’s oil and gas industry relies on combustible gas detectors for identifying leakage accidents. RTI and CUP recommended direct inspection and maintenance (DI&M) of equipment on a systematic basis using leak detection devices—such as ultrasound detectors, infrared cameras, or “sniffing” devices—that can show the inspector exactly where the leak is and calculate its flow rate.
“The DI&M process and detection technologies would allow the oil and gas companies to monitor their equipment for leaks and spend their resources wisely to repair the most significant leaks first,” Gallaher said.
Changing Practices
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The “Triple Bottom Line” to Methane Recovery and Use Financial – Create New Fuel: Recovered methane can be processed into natural gas, a clean energy source that would have been lost. Social – Slow Global Warming: Methane emissions can be significantly reduced with currently available, cost-effective technologies and can help slow global warming over the near term on a scale comparable to reductions of carbon dioxide emissions. Environmental – Cut Pollution: Natural gas can improve air quality by offsetting the use of coal, which releases more pollutants (and greenhouse gases) into the atmosphere. |
RTI and CUP’s recommendations were presented to a panel of international and Chinese environmental scientists and industry experts in April 2008. The project is now in the process of recruiting Chinese oil and gas companies to conduct demonstration projects using recommended technologies from the study.
“We hope that by applying these technologies in a small way, the companies will see the economic, social and environmental benefit of methane reduction and will roll out the technologies across their organizations and the industry,” Gallaher said.
In addition, RTI’s partnership with CUP, China’s leading academic and research institution in petroleum engineering, will transfer the lessons of the Methane to Markets project to the next generation of Chinese engineers.
“Today’s students will know the importance of and techniques for detecting and reducing methane emissions when they become tomorrow’s field managers in the oil and gas industries,” Gallaher said.
e-mail mpg@rti.org
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