Methane Mitigation

IEA, the International Energy Agency, lists LDAR—leak detection and repair—among the available measures. Replacing equipment that releases gas during operation, or capturing and using that gas, can help too. In Flare Gas Mining and Landfill Gas Mining, the mining machine consumes electricity downstream of a generator. Its income may help a project go ahead. But it neither repairs a valve nor captures methane itself. Ask which changes would happen without miners and which the new project actually enables. [1]

First establish a baseline: an evidenced estimate of the situation without the project. An existing flare, equipment that burns surplus gas, must not disappear from this account. U.S. EPA, the US Environmental Protection Agency, describes continued collection and flaring of landfill gas even after electricity generation ends. If the gas was already being burned, a new generator does not automatically prevent its entire release. Consider previous customers for the gas and what actually happens during outages too. [5]

Methane’s chemical formula is CH4. U.S. EPA explains that some can pass through an engine unburned; leaks can also occur in the fuel supply or during malfunctions. Electrical efficiency is not methane destruction efficiency: the former describes how much fuel energy becomes electricity, the latter the fraction of incoming methane transformed during combustion. A generator is therefore not emissions-free. We need to understand the entire gas flow, rather than just the electricity shown on a meter. [3]

IEA distinguishes wide-area satellite monitoring from targeted measurements of smaller sources. Coverage and the size of leaks they detect differ. An image showing nothing does not establish zero annual emissions. A project needs gas flow, the CH4 fraction, operating time, leak data and measurement uncertainty. Record downtime and missing periods too. A gap in data cannot be presented as verified savings: make clear what was measured and what was merely estimated. [1]

U.S. EPA explains GWP, global warming potential: a way to compare the warming effects of different gases over a chosen period. GWP20 and GWP100 use time horizons of 20 and 100 years. Methane stays in the atmosphere for less time than carbon dioxide, so the horizon strongly affects its weighting. Conversion to CO2e, carbon dioxide equivalent, puts climate effects on a common scale; it does not make the physical masses of gases identical. State the method and factor used. Avoided emissions are not the same as CO2 actually removed from the atmosphere. [4]

Take our own simplified example for CH4 alone: a project emits 1 kg of methane during the period assessed. The evidenced scenario without it would release 100 kg, giving a difference of 99 kg. But if only 2 kg would escape without the project, the difference is just 1 kg. The operation has not changed; the comparison has. This comparison against a baseline underpins GHG Protocol project accounting. Short for Greenhouse Gas Protocol, the name refers to a set of standards for calculating and reporting greenhouse gas emissions. Our example is not a complete CO2e balance: we are tracking methane alone, without other gases or associated activities. [2]

GHG Protocol requires consideration of significant secondary effects as well as the main effect. For a mining project, examine changes in gas collection, auxiliary electricity, transport and any change in fossil gas production. This does not mean indiscriminately counting every nearby activity. It means changes caused by the project relative to the same baseline. If an effect is insignificant and excluded, the justification must be available. Otherwise an attractive figure may simply reflect leaving inconvenient parts of the operation out of the calculation. [2]

Here, an emissions credit means a unit of emissions reduction recognized under a particular program’s rules. GHG Protocol distinguishes project emissions reductions from a corporate inventory, an account of the organization’s emissions. Its method does not itself guarantee acceptance into an emissions-credit program. A program may also require additionality: evidence that the credited reduction would not occur anyway without the relevant support or project, under its rules. An honest claim states the period, baseline, measurements, uncertainties and method. Assess mining income separately. A profitable operation may lack evidence of an additional climate benefit, while a genuine reduction in leakage may be unprofitable. [2]