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Capturing Carbon With Garbage Heaps
davide marney writes "In a Washington Post opinion piece, Hugh Price argues that using a decidedly low-tech solution to sequestering excess carbon — making piles of agricultural waste — is better than many 'green' solutions already in practice. Sometimes the easy answer is the right answer. After all, it's how coal forms, and we know that works pretty well."
but how can you have huge federal bureaucracies and sell carbon credits and implement strange new taxes if everybody uses the simple and elegant solution? Clearly this proposal has a fatal flaw.
Better use the waste to make biochar. No artificial fertilizer necessary.
Kinda had this thought some time ago . . . plus, locally, we have numerous "brown fields" that are so loaded down with industrial waste from the 19th and 20th century that they aren't entirely safe for humans and certainly can't grow much of anything, outside of maybe, oh I don't know, gypsum weed. Or maybe jatropha curcas, I hear that stuff is pretty hardy.
I don't know what plants like gypsum and/or jatropha would actually pull out of soil like that, aside from water and some other nutrients, but if they could be used to leech toxins/industrial waste out of the soil, they could then be "piled high" to create a combination CO2 heap and toxic waste dump. Of course, you'd just be moving some of the nasty crap that made "brown fields" possible from one "brown field" to the next, and I would expect the NIMBYs to be rather upset about that. Still, seems like an okay idea. Let's face it, if you've got an area cordoned off to be your CO2 dump, it's not like you want anything disturbing it anyway, so may as well infuse it with horrible toxic waste that would cost a fortune to dump elsewhere.
One word methane. It results from anarobic decomposition and is a far more potent greenhouse gas than CO2.
One of the examples was to bury agricultural waste instead of plowing it into the ground. The obvious problem is that the "waste" is what becomes the soil in a few years, putting back minerals, nitrogen and other elements that the plant needs to grow. Without putting this "waste" back into the ground, the only way to get the same full, lush plants that are soaking up all this carbon is to use man made fertilizers, which are a big enough problem with ground water that we don't need to adopt a new agriculture method that requires even MORE of them.
If we could separate out all the carbon from our garbage and bury it in the way he talks about, great, there will be coal in a few millennia. But generally speaking, this sounds incredibly unworkable and naive.
Tequila: It's not just for breakfast anymore!
Price says, "Without access to oxygen, bacteria cannot break down plant material."
Price, who obviously knows nothing about biology, is forgetting about the vast majority of all species on the planet: anaerobic microbes. They are quite good at turning organic material into carbon dioxide and methane. This happens in all animal guts, including yours, as well as anaerobic digesters, soils, underwater sediments, bogs, etc. His garbage heap "solution" sounds, to me, like an anaerobic digester. It would transform the waste into carbon dioxide and methane. Methane, by the way, has a green house gas equivalent of about ten times that of carbon dioxide. However, you can capture the methane and burn it to generate electricity. But, there's nothing novel about this; we've been doing it with our agricultural waste for decades. Especially in Europe where, for example, Germany has 4,500 cooperative facilities solely for the purpose of anaerobic breakdown of agricultural waste and capturing the methane produced, to be used as green energy.
This cannot work the way TFA suggests: TFA is far too simplistic. Just piling up agricultural byproducts would only produce a large compost heap. It would remain bioactive until it either caught fire through spontaneous combustion or turned into soil. Either way, the carbon has not been sequestered; it remains in the biosphere. The cycle of repose in the large heaps is just too short to be useful.
That said, there is an approach that would work, in those parts of the world that have snow in the winter. We could create artificial peat bogs.
Dig pit a couple of acres in cross section and a thousand feet deep. Make it water tight and fill it to the brim with icy cold (4 degree C) fresh water-- it doesn't have to be potable and sea water might work but I only know about fresh water peat bogs, Add a compression mechanism, such as a sinkable platform the size of the pit, weighed down with some of the rock from the digging. Let it sink to the bottom of the pit. Chip the plant material down to a size that will compact easily, then slowly force the chippings under the compressor. That's it. Once operating, the main cost is that of stuffing the new chippings into the bottom of the pit.
There will be some slow anaerobic activity but so long as the pits are small in diameter relative to their depth, the water will stay cold, stagnant, and deoxygenated. The chip injector needs to be designed to avoid stirring the waters: you want that stagnation. You want dead, cold water that will minimize bioactivity.
A peat farm of ten pits each 2 acres by 1,000 feet deep could accept more than 4,000 acre-feet of agricultural byproduct each year for one hundred years before it fills, and then it would continue operations indefinitely. For at that point the compressor could be removed since the weight of the old peat would be enough to hold new chippings at the bottom, and the top few feet of finished peat could be removed each year for longer term storage elsewhere. Such as tilling it into desert sand dunes to stabilize them or stuffing it into depleted mine shafts, or storing blocks of the stuff in the Greenland or Antarctic iceboxes.
Eventually most of the carbon in the peat would return to the biosphere, but this approach would help buy us time to get off our fossil fuel dependency. For that matter, peat is not only a useable substrate for developing petroleum products, it is an effective fuel all by itself. It could be that peat farms could directly replace coal and oil, once we get our needs for petrochemicals down to sustainable levels.
Will