carbon monoxide emissions as a power source

It's more likely methane, and this is a very good thing to be doing. Not only does it turn a waste into a resource, but it prevents emissions of methane to the atmosphere, which is important in terms of mitigating global warming. Although there's a lot less methane in the atmosphere than CO2 (the most commonly cited greenhouse gas) methane's impact on a per-unit basis is much, much greater. That is, a mole of methane has about 4 times the impact (IIRC) on atmospheric heat retention than a mole of CO2. So keeping it from getting out is a good thing, and more and more landfills are taking this approach. Now we just need to figure out what to do about cow farts, which are actually a surprisingly significant source of atmospheric methane.