True, but it's an aerobic decomposition that produces CO2. Landfills tend to create anaerobic environments, where decomposition produces methane. Both are greenhouse gases, yes, but methane is the more potent of the two.
It's still good news, since methane is a more potent greenhouse gas - depending upon the timeframe and calculation method it's generally reckoned to have between 30 and 100 times the warming potential of C02 [1]. Moreover a power station then has a CO2-rich exhaust stream, which is probably the best place for industrial carbon capture.
Sunnyvale does this! The "Sunnyvale Materials Recovery and Transfer Station" (SMaRT Station) is out by the bay, and there is a waste water treatment plant right next door. Methane is captured from "capped" landfills and is used to power the treatment plant. I believe the plant is nearly 100% powered by these captured gases.
Doesn't smell great over there, but it sure is interesting and pretty smart!
Only in the same sense that farming is "natural" - we're using biological processes that would never happen without our careful construction and maintenance of the circumstances.
> i.e. perhaps the best reason to recycle or compost is to avoid the methane emissions from natural decomposition.
Uhhh, I think you may want to rethink that. Rotting things, whether in a landfill or in your ecologically principled compost heap in your back yard releases methane.
Methane is produced by anaerobic decomposition; composting is defined by the regular aeration (and sometimes watering) of the compost pile, which allows aerobic bacteria to break down the pile more cleanly. You do still get some GHGs, but much less.
Your own references point out that aerobic and anaerobic composting are different processes; the latter, which is most of backyard composting (if your heap ain't hot, it ain't aerobic), produces about as much methane as a landfill does, without the ability to collect and burn off the methane.
It boggles me that people emotionally or tribally react to a fact about how chemistry works, google things which support their emotional reaction, and ... don't read what was in their citation.
The first reference does not refer to anaerobic methods as "composting", but as fermentation:
> Decomposing organic material in anaerobic conditions — by microbes in the absence of oxygen — releases methane into the atmosphere. Anaerobic fermentation is common in landfill and open stockpiles such as manure piles [azernik: Manure piles are the second big contributor to methane emissions listed in OP.]
The second one just refers to "anaerobic decomposition".
In both cases this is something they mention as the alternative to composting, i.e. they literally define composting by its use of aerobic decomposition methods.
And yes, I agree that this is a complicated biochemical process that should be done by professionals in dedicated facilities (EDIT: which is where most composting happens in California), not in people's backyards. Where did you hear me arguing for amateur backyard piles?
That sounds like the sort of thing that could be fixed by educational material.
A little methane from the back yard is still better than landfill. But the math for commercial composting vs amateur might need some scrutiny. Transport to the composting facility should also be part of the arithmetic there.
Worth noting / just pointing out : one common approach to orchard composting [which influences some backyard operations] is to avoid turning it in an effort to 1) promote fungal development and 2) save labor/money
Yeah methane is released inside a compost pile but some of it is consumed by the compost pile by other reactions. That is literally the point of a compost pile versus just a pile of garbage.
Another explanation[1] that shows how it's not just the cost of escaping Earth gravity (which is high enough already) but the delta-v required to de-orbit. It's easier to throw the garbage out of the solar system than it is to descend into the Sun.
The state of the art high tech proposal is to grind everything to a powder, put that in a high temperature plasma furnace for demolecularization, then extract raw materials for reuse. This kind of process would in theory result in waste dumps being seen as excellent competitive sources of materials such as gold and rare earth elements.
There are now a few startups trying to make home/DIY anaerobic digesters that you can collect the gas from. Would be interesting for e.g. keeping a greenhouse warm year-round without the electricity spend.
This is of no use in the developed world for a normal house. Try getting your home owners insurance to pay off a claim against an accident involving this. Also, according to its specs you can get 2hrs of cooking per day if you supply 5 gallons of animal manure. That's a tiny amount of energy compared to modern energy needs.
For most people this would be a novelty, maybe you could run an outdoor grill off of it.
In a landfill, only anaerobic bacteria can survive. These are unable to break down organic material as cleanly as the aerobic bacteria in a managed compost pile. See my comment at https://news.ycombinator.com/item?id=21483584 for links to sources.
They can; this is generally referred to as "biogas" (https://en.wikipedia.org/wiki/Biogas). It's equivalent to Carbon Capture and Storage, but for all of these methane releases. It's only used on a relatively small scale in rural areas, mainly to save money on natural gas (which is also basically just methane) and its related distribution infrastructure; I haven't heard of any successful projects to harvest biogas on the large scales required to really cut down agricultural and landfill emissions. The main challenge seems to be purification, as biogas has all kinds of nasty contaminants that are bad for people and machinery.
> Landfills accounted for 41% of the source emissions it identified, manure management 26% and oil and gas operations 26%.
i.e. perhaps the best reason to recycle or compost is to avoid the methane emissions from natural decomposition.