[USCC] Compost Digest Vol 29 # 6- Response to Craig CH4

[Edo McGowan]

Re: Compost Digest, Vol 29, Issue 6. Methane emissions from composting (Craig Coker)


If one were to pull up the following and refer to Appendix F, the data on conversions are presented. Loren Faundahl of EPA and I spoke some weeks ago about this. Her office supplied me with the following: each ton of sewer sludge will produce somewhere between 2,000 and 4,000 cu ft of CH4. The average is about 3,000 cu ft. Using the data in Report#:EIA/DOE-0573(98), November 5, 1999, 

1 thousand cubic feet of methane = 42.28 pounds. 

Thus using the data supplied by Loren and her office, and assuming the 3,000 cu ft average, the product is 127.28 pounds, the 34.5 supplied by Maureen is thus a substantial under estimate. Since CH4 eventually shifts to CO2 at a conversion of about 21X, the average ton of sewer sludge when land applied or composted warrants more attention. If however, this material is used as a fuel source, the evolution of greenhouse gasses is essentially eliminated.

Assume, for example the roughly one half million tons that are moved out of the LA Basin into the closed and over subscribed air basin around Bakersfield. Doing the math assuming the above, we obtain the following

3,000 cu ft/ton X 500,000 tons yields 1,500,000,000 cuft CH4 or 3.15 x 10/10th cuft CO2. I think my math is valid, but the data are available to recalculate independently. See what you come up with. You may also compute BTUs and kWh to see what is being thrown away.

Cheers----------------Edo