by BRAD MACDONALD

There has recently been a lot of discussion on Landfill Gas Capture (LFG). The gist:

The material in a landfill is packed very tightly, which creates an anaerobic (no oxygen) environment. Some of the materials in landfills decay in this environment and produce biogas (methane, carbon dioxide, and trace amounts of other gases). Organic matter is the most prominent of these materials. Some landfills in the US are now capturing the biogas by sinking pipes into the waste and sucking it out. This biogas can then be cleaned and liquefied to create liquid natural gas, which is used to power truck fleets, including garbage trucks, or simply flared to reduce the negative effects it has on the atmosphere.

So what’s the problem? Why all the fuss about separating organics out and sending them to anaerobic digestion processing facilities? It sounds like a landfill is just one giant anaerobic digester itself. If we’re keeping major greenhouse gases from escaping to the atmosphere and we’re getting some energy out of it, why don’t we let all of our organics go to the landfill and capture the methane gas that way? It would sure eliminate the inconvenience of sorting all that food waste out in our kitchens, we wouldn’t have to deal with a bucket of scraps that stinks, and it would keep more collection trucks off the road, right?

Unfortunately, wrong. The status quo presents, at best, a severe inefficiency, and at worst, a source of pollution and a major capital expense. Let’s break it down.

LFG facilities capture about 60%-90% of the biogas produced. That means that 10%-40% is still being released, un-flared into the atmosphere. And only 20% of landfills in North America actually have the technology to capture the gas, let alone turn it into fuel. AD, on the other hand, captures almost 100% of the biogas generated, meaning 100% of the gas is going to energy production, and 0% is going to the atmosphere. AD can also capture the remaining organic material once the biogas is released and compost it into a useful product, rather than letting it rot.

A landfill IS like a very big anaerobic digester – one that operates on a 20 year timeframe. Most dry AD processes, like Harvest’s, speeds up biogas production to four weeks. And AD can keep on taking organic material indefinitely, while a landfill fills up, meaning significantly less capital costs. The biogas produced by organic material is relatively clean, but it mixes with other things in landfills that release toxins when they decay, like cosmetics and heavy metals. That leads to the $15.5 million price tag to capture and clean up landfill biogas and make it usable. If organics never see the landfill, we can extract the methane gas while it is still clean, avoiding the high costs of purifying it of the toxins. So what about the convenience factor? Isn’t it still more trouble than it’s worth?

Sure, you do have to take the extra effort to decide where that banana peel or coffee filter goes. But here’s a helpful trick – if it was once alive, it can go to the composter. As for the smell, unfortunately, those food scraps are going to stink no matter which bucket you put them in – the garbage can or the organics bin. So line your scrap bucket with an old newspaper, a paper towel, or a brown paper bag from the grocery store to reduce the smell, and empty and rinse it often. And encourage your municipality or local hauler to collect your organics bin every week and your trash every other week. This will get rid of the smelly stuff more frequently while cutting down on collection costs. And speaking of collection, adding a third bin won’t necessarily increase the number of trucks on the road. If you change the frequency of collection as mentioned above, you can largely offset the costs and reduce the number of trucks that stop at your door every week. And remember, the volume of waste being collected is the same – sorting organics doesn’t increase the amount of waste at your curb. And the same volume of waste equals the same number of trucks driving around your city.

Now, we’re not saying there’s no place for landfill gas capture. There is bound to be some organics that make their way to the landfill, and there is other material that breaks down and releases biogas. Let’s just make it as efficient as possible.

Reach out to Elizabeth Lowell. Email her at elowell@harvestpower.com

Harvest Power

Originally posted 2010-03-10 08:26:04. Republished by Blog Post Promoter

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