In our last post on the topic, we talked about CO2e being a handy unit of currency – one which we can use to make sense of the different kinds of greenhouses gases and their effects.

Even though CO2e may be closer to an estimate than “exact change,” it gives offset providers (and projects) the ability to roughly quantify the impact of a carbon offset project.

We already know that not all greenhouse gases are created equal. And it might be strange to learn that sometimes offset projects create CO2 emissions in order to offset carbon. Are you scratching your head?

Think of it as the lesser of two evils. Take methane gas flaring projects, for example.

Reducing methane (CH4) gas from seeping into the atmosphere may have a bigger overall impact on slowing down global warming, even if carbon dioxide is produced in the process.

That’s because each ton of methane (as we learned earlier) is 21 times more potent a greenhouse gas than a ton of carbon dioxide (source: EPA). And according to scientists, it takes about 12 years to break down.

Flaring turns one ton of methane into around 3 tons of carbon dioxide (4 light hydrogen molecules are replaced by 2 heavy oxygen ones). But even so, it’s a good deal for global warming, since we’ve turned 21 tons of CO2e into just 3. And the energy generated by flaring can replace fossil fuel sources which themselves would generate more CO2.

Where does methane come from? It is a main component of natural gas, and is produced by biological anaerobic processes (such as fermenting cow manure). Once in the atmosphere, the methane gas absorbs infrared radiation that would otherwise escape to space. This property makes it a contributor to the warming of the atmosphere, and a bonafide greenhouse gas.

Image source: The EPA

Methane gas is also emitted from coal mines and released in landfill sites. We’ve listed 15 industrial methane projects on Carbon Catalog, such as the Crossroads Landfill Gas Capture in Maine, operated by TerraPass.

A second project that neutralizes methane from coal mines is the Gateway Coal Mine Methane Capture in Pennsylvania. Supported by Carbon Neutral, the project expects to offset some 133,000 tons CO2e between 2006 and 2010.

There is a 1-page PDF that makes a good read here, but the gist is this: the shaft to the unused mine cannot be completely sealed, and the methane gas from inside the earth is leaking into the atmosphere.

Using a compressor, the methane is piped to a flare and when burned it is converted into less potent carbon dioxide. As we mentioned above, it’s still a greenhouse gas, but a less damaging one.

While planting trees to suck up carbon dioxide may be a good solution for the long term, some believe that methane is the grand-daddy of greenhouse gases and not just “the other greenhouse gas.” They argue that methane’s capture and recovery might be more meaningful to focus on in the short term, when there is still time to prevent a climatic apocalypse. Yikes.

::Source EPA (for more reading)