Processed poop and plants provide methane for power
A nice thing about chemistry is that it’s source agnostic. Matching atoms from one source are as good as any other, which is why the methane we’re capturing from fresh sewage is just as good as the gas we’re extracting from deposits in the ground. Actually, that’s not entirely true, as the fresher sources of methane are also offering environmental benefits, making them more attractive places to get chemically identical CH4.
Benefits of a byproduct
While people have worked hard to extract methane, as natural gas, from the ground, wastewater treatment plants usually have the opposite problem. As sewage breaks down, it releases a lot of methane that had to be addressed in order to avoid becoming a fire hazard, or simply vent it as polluting greenhouse gas. Neither option could be considered terribly efficient or constructive, and now more and more waste treatment plants are trying to harness that unavoidable methane as a fuel source.
One option is to turn the wastewater facility into a hybrid power plant. To dispose of the methane, it’s burned to power turbines and generate electricity. That electricity can then be sent out to the grid, or at least help power the water treatment facility itself. In Colorado, engineers are refining the methane and packaging it for use in other power plants. The initial beneficiaries of this purified waste byproduct are natural gas vehicles, such as buses and garbage trucks. Once contaminants like water and oxygen are filtered out, the biomethane is indistinguishable from other sources of natural gas, making it usable in a wide variety of applications.
Mixing and matching
Between human waste and farm animals, there’s no shortage of fecal fuel sources. As operations have ramped up in Colorado, they’ve discovered one caveat about these sources though— even if the quality of resulting methane isn’t a concern, they have found that mixing different forms of organic materials for decomposition can yield greater returns per pound of waste. So rather than source their methane strictly from the sewer, they’re mixing in food waste as well, which not only increases their output, but of course helps with yet another collection of material we’re not making the most of. Basically, any food source for us can also power our buses or power plants, either before or after we’ve eaten it.
Source: From Poop To Power: Colorado Explores New Sources Of Renewable Energy by Dan Boyce, NPR.org