Final Report - Ohio Department of Transportation

Based on the overall results of Table 5, the average bio-char production was 39.6 %. The
remainder of the mass (60.4%) was given off as byproducts. Of these byproducts, the average
collection efficiency (i.e. the recovery rate) was 56.9%. The remainder of the byproducts
(mostly smoke and water vapor) was discharged into the ventilation system. To put these
numbers in perspective, if a yard waste carbonization process with these properties was applied
to the whole of yard waste generation in Cuyahoga County, the production of total bio-char and
byproduct production would be as follows.
Annual U.S. Yard Waste Production Estimate - 32.9 million ton/yr (USEPA 2009)
U.S. Population Estimate - 307,006,550 (USCB 2009a),
Cuyahoga County Population Estimate - 1,275,709 (USCB 2009b).
Total Biochar - 32.9*10 6 ton/yr * (307,006,550 c) -1 * 1,275,709 c * .396 = 54,160 ton/yr.
Total Byproduct - 32.9*10 6 ton/yr * (307,006,550 c) -1 * 1,275,709 c * .604 = 82,550 ton/yr.
In producing this, a portion of the byproduct will be aqueous. Using the average moisture content
measured for all samples of yard waste, this fraction would be as follows.
Aqueous Byproduct - 32.9*10 6 ton/yr * (307,006,550 c) -1 * 1,275,709 c *.288 = 39,400 ton/yr
The remainder of the byproduct would be organic materials.
Organic Byproduct - 32.9*10 6 ton/yr * (307,006,550 c) -1 * 1,275,709 c *.316 = 43,100 ton/yr
However, it should be noted that not all of the organic fraction was actually collected in liquid
phase. Some of this escapes in the gaseous discharge. The overall collection efficiency of this
fraction was 57%. Obviously, these estimates assume that all yard waste is collected and
successfully carbonized, but the production potential seems adequate to generate a material and
revenue stream that would help offset the cost of the carbonization operation.
38