Anthropogenic Peat

In a recent letter, Robert R. Hitch takes issue with efforts to reduce fossil fuel use, reasoning that any such curtailment of fuel use will lower its price and make it more available to others (C&EN, Dec. 4, 2006, page 6). He finds all such plans and schemes not only counterproductive but also ineffective, as nothing so far tried actually reduces the rate of CO₂ emission. He proposes instead to reduce the production of fossil fuels by legislation; he realizes this poses a huge problem but calls it a "real solution," not mentioning what this will do to the cost of energy. He closes by asking if anything else is out there.

Yes, Mr. Hitch, something else is out there. You state (correctly) that global warming is due primarily to the increase in CO₂ concentration in the atmosphere, and then proceed as though the only way to control the level of this offending gas is to restrict its emission rate. You are, of course, not alone; just about everyone else, including, unfortunately, the editors of C&EN to date, ignores the fact that CO₂ levels can be affected by removal and segregation much more efficiently than by simply trying to reduce emissions. This procedure works by removing dilute CO₂ from the atmosphere by the growth of biomass, which is converted by anaerobic digestion to yield methane, CO₂, and stabilized digester residue. The first of these products is used beneficially; the latter two are segregated to be kept out of the active cycle, lowering CO₂ levels if emission rate stays where it is.

This process is called Anthropogenic Peat (AP) because the stabilized digester residue is like peat made in nature by the same process. The best plant for this purpose is sugarcane, the most efficient large converter of CO₂ to biomass we now have; this may well change in the future. At this time, we know a lot about growing sugarcane, and there is quite a bit of suitable land available. We need about 150 million acres worldwide to stabilize CO₂ levels if the emission rate stays unchanged. And it pays for itself: CH₄ produced from cane this way is much more profitable than sugar from the same crop; its break-even cost is in the vicinity of 50 cents per million cu ft.

On top of these virtues, AP interacts favorably with at least 16 of the top 20 problems facing the world, as listed by the World Bank and the Union of Concerned Scientists. This is one of the things out there, Mr. Hitch; it is the only one known to me that will do the things you (and everyone else) wants done without upsetting a world that runs on energy and demands more all the time. This has been presented at technical meetings and published over the past 15 or so years; another paper is being prepared to quantitatively verify the earlier calculations, using data published by others totally apart from the AP process, so we can be confident of the effect of AP on CO₂ levels in the air.

H. A. Hartung
Collingswood, N.J.