Pipeline vs. truck transport of beef cattle manure

Abstract

Anaerobic digestion (AD) of manure can be conducted at a wide range of capacities. As capacity increases, economies of scale in capital equipment are realized but transportation costs increase as manure must be carried longer distances to the plant site. In this study, we evaluate the cost of pipelining manure from beef cattle feedlots and digestate from an AD plant as an alternative to truck transport. Pipeline transportation cost for manure is minimized at a slurry concentration of about 12%; low concentrations require a larger pipeline, and high concentrations require higher pumping costs. Pipelining costs are highly scale dependent, while trucking costs are virtually independent of scale for a given carrier size. A stand-alone manure pipeline competes with trucking at 90,000 head of beef cattle. Digestate volume is about 2.4 times the volume of manure and a stand-alone digestate pipeline is more economic than trucking at 21,000 head, and a two-way pipeline at 29,000 head. Incremental net fixed costs for trans-shipment from truck to pipeline are low for manure and zero for digestate because equipment installed at the pipeline inlet eliminates the need for identical equipment within the digester plant. A manure pipeline must run for a minimum distance to recover the incremental fixed cost of trans-shipment; at 300,000 animals, the minimum economic pipeline distance is 9 km. Pipeline transport of beef cattle manure has the potential to reduce overall transportation cost to a large centralized digester in areas such as Dodge City, Kansas or Lethbridge, Alberta where very large numbers of beef cattle are in feedlots. A 50 km pipeline carrying manure from 300,000 beef cattle has an overall transport cost of 40% of ongoing truck transport.