Question and Answer
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QUESTION:   I recently heard that as garbage breaks down it gives off methane – a very concentrated greenhouse gas. Is this true? If so, what do landfills do to address this problem?

ANSWER: It’s true, methane and carbon dioxide (CO2) are both emitted from rotting garbage. At landfills, the scraps from that fabulous dinner you almost finished, together with tons of other organic wastes, slowly decompose. As this matter breaks down, it generates methane and CO2 (along with a small percentage of other nasty gases). And as you pointed out methane is a particularly dangerous greenhouse gas – 21x more potent than CO2.


Landfill managers can reduce or eliminate methane emissions in one of two ways, either by burning it off with a flare (which creates CO2), or building a power plant and capturing the methane to make electricity. Not all landfills produce enough methane for this to be a viable option. American Canyon produces a small amount of energy that’s used by the water treatment plant. If you want to see one of these renewable energy facilities in action take a trip over to the central dump in Sonoma County.

From landfill gasses alone, this County-operated plant has generated 7.5 megawatts of electricity a day - enough to meet the power demands of 7,000 households. That could power the entire town of Windsor!

So, you might ask, if this is such a great form of renewable energy why don’t more landfills have power plants? Well, first off there’s that annoying issue of finances. Building the structure to maintain a flare might cost a half million, while a power plant might cost $10 million, as did the plant in Sonoma County. Still, building a plant can make sense because the landfill can then generate revenue from selling the electricity. In addition, this renewable energy means that less energy has to be produced from sources such as coal, natural gas and nuclear. And finally, these plants prevent a particularly bad greenhouse gas from entering the atmosphere.

But even if capitalizing on this renewable energy source seems to make sense there are a few other reasons many landfills shy away. The first is that even though regulatory groups recognize that landfill gas power plants reduce CO2 and methane emissions, they still regulate these plants as if they were any other fossil fuel or natural gas plants.  This drives up the cost of regulatory compliance. The second reason is that historically only large landfills have been required to eliminate methane.  If a landfill is relatively small, they just have to put in a pipe so the methane can escape and prevent any gas explosions (minor detail). But this may be changing.

Under California’s latest regulations, all landfills may be required to eliminate methane by burning it or capturing it for power production. This progress in regulatory oversight may also help make methane capture a more cost-effective energy source. We’ll keep you updated!