Fugitive Methane Containment
Containing Fugitive Methane Emissions
Methane mitigation has gained attention from policy makers as one of the most cost- effective and timely strategies to limit warming to 1.5˚C. According to the Global Methane Assessment released by the UN Environment Program, curbing human-caused methane emissions by 45% would avoid nearly 0.3°C of global warming by 2045. The Fugitive Methane project is developing opportunities for methane capture and destruction across a range of sources including agriculture, coal mines, and abandoned oil and gas wells.
Mitigating Emissions from Mines
Methane is released in underground mines when a coal seam is disturbed to extract the coal. For the safety of miners, methane concentrations must be kept below 2% using ventilation systems that release ventilation air methane, or VAM. VAM is the largest source of methane emissions at active coal mines. According to the EPA Coalbed Methane Outreach Program, nearly 60% of methane emissions at active coal mines are released via VAM systems at relatively low concentrations. Emissions from wells drilled prior to mining operations are typically of higher concentration and represent about 8% of coal mine methane emissions. Flares have successfully been used to mitigate this methane.
VAM and RTOs
Regenerative thermal oxidizers (RTOs) are systems used across industries which generate VOCs. RTOs oxidize low concentration (.3% to 1.5%) methane and are described by the EPA as the “only commercially operational technology capable of using VAM as a primary fuel at methane concentrations below 1.5%.”
Flares can operate at greater than 95% efficiency and are a quick and effective way of destroying methane, but typically need about 30% methane concentration to operate. Flaring technologies can reduce methane emissions from mines where use of RTOs or pipeline injection is not possible or economic.
CC Lab Efforts
Through building relationships with industry experts, we have developed several potential projects to deploy novel technologies and approaches for the mitigation of mine methane.
Mitigating Emissions from Abandoned Oil & Gas Wells
According to the 2019 US Green House Gas Inventory, abandoned oil and gas wells emit approximately 6.6 million MTCO2e per year. An abandoned well is generally defined as an oil or gas well for which there is no known operator responsible for remediating and plugging the well, as required by regulation. The EPA estimates the number of abandoned unplugged wells in the U.S. to be between 2.3 and 3.2 million.
Plugging & Methane Mitigation
Current well remediation regulations require plugging the well with concrete to protect groundwater resources, prevent surface pollution, and stop methane emissions. This is an expensive (an average well can cost $30,000 to $170,000 to plug) and carbon intensive process, also limited by an ability access the well site. Research is needed to innovate well plugging techniques, lower the cost, and to better characterize and quantify methane emissions from abandoned wells.
CC Lab Efforts
Our team is supporting research efforts to better quantify and measure methane emissions from abandoned oil and gas wells. The economics of well plugging are a challenge, as emissions from most wells are too low (< 1 MTCO2e per year) to cover costs through carbon offset credits alone.
Mitigating Emissions from Agriculture
Agricultural activity is one of the largest sources of methane emissions globally and is the largest source in the US – responsible for 10 million tons of methane in 2019. Emissions from agriculture come mostly from livestock—approximately 30% from enteric fermentation and 9% from manure management.
Manure Management & Methane Mitigation
The amount of methane generated from manure depends on how that manure is processed. If manure is composted or spread directly onto croplands, emissions are minimal. Most livestock farms store manure in either covered or uncovered lagoons which rapidly become anaerobic, creating conditions for methane production. Uncovered lagoons release methane and other volatile gases directly to the atmosphere. Lagoons are often covered for odor control rather than methane capture and are not necessarily gastight. However, gastight covers in conjunction with flaring, may be a more economical way to mitigate manure methane at small to midsize farms. Manure methane can also be purified and injected into pipelines or combusted for onsite electricity and heat generation.
Enteric methane emissions are both low-volume and dispersed across the US. Enteric emissions are impacted by several factors, including individual animal genetics, feeding regimes, and environmental factors. Proposed solutions include selective breeding to decrease methane production, altering feeds to include more high-energy, low-fiber material, amending feeds with a small dose of a methanogen-inhibiting compound, or capturing and destroying emissions at the mouth of the cow with the use of a “cow mask.”
CC Lab Efforts
Methane destruction is not legally required at livestock farms in the US so any methane destroyed may be sold as carbon offsets. The CC Lab is interested in researching the viability of covered lagoon and flaring systems and addressing methane emissions from early stages of manure processing. The Lab is also investigating the potential to capture and destroy enteric emissions at Concentrated Animals Feeding Operations (CAFOs). CAFOs are well-ventilated to prevent the spread of disease, and vent high volumes of low-concentration biogas to the atmosphere. By retrofitting ventilation systems with catalytic technology, the CC Lab sees a new path forward for methane destruction at 450,000 CAFOs the United States.