(548r) A Life Cycle Cost Analysis of a Cattle-Based Anaerobic Digester Operation in Iowa

A
Life Cycle Cost Analysis of a Cattle-based Anaerobic Digester Operation in
Iowa.

Aui A.^b and Wright M. M.^ab

^aBioeconomy
Institute

^bDepartment
of Mechanical Engineering

Iowa State
University

Anaerobic
digestion (AD) is an attractive and beneficial process for the conversion of
agricultural, industrial and commercial waste into clean and useful renewable
natural gas. Anaerobic digestion is a promising approach to achieving the
economic and environmental goals set forth in the Iowa Energy Plan. This project
aims to provide a life cycle cost assessment (LCCA) for Iowa anaerobic
digesters and to identify opportunities for their profitable operation. Recent
technological and policy developments have created opportunities to develop
anaerobic digestion by providing an array of options to producers, farmers and
businesses.

This
study evaluates the different costs that affects the conversion of manure into
biogas for heat, power, and renewable natural gas markets. It describes the
capital and operating costs involved in the industrial operations of anaerobic
digesters, while also evaluating the role of federal and state incentive
programs in reducing commercialization risks. Finally, this project creates a
business plan for stakeholders to evaluate the different opportunities and
feedstocks such a cornhusk, rye and wheat, available for the development of
anaerobic digesters in Iowa.

Current
results indicate that an anaerobic digester attached to a 2400 head of cattle
operation, that is co-digested with glycerin and cornhusk has 950 kW of
generation capacity. The discounted cash flow rate of return (DCROR) analysis
suggest that at a capital cost of $4.78 million, this project could achieve an
internal rate of return of more than 5.50% at electricity prices of 12.0 ¢/kWh.
By replacing cornhusk with rye and wheat, the internal rate of return is still
in the upper range of 5%. Additionally, wheat has a higher net present value
average in compared to the other feedstocks. The main contributors to the cost
include capital, labor, and operating capacity. Solid digestate credit is an
important source of revenue based on its C:N content. The role of tipping fees
largely depends on the energy content provided by the feed. In particular,
glycerin has been shown to enhance the biogas potential of animal manure.
Future work will include investigating the aspects related to upgrading biogas,
its environmental impacts, and exploring other major policies or incentives
that influence an AD system.