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Manure Value & Economics

The organic matter in manure contains energy that can be utilized in biological processes such as anaerobic digestion or in thermo-chemical processes such as combustion or gasification.

Using Manure For Energy Is an Old Idea

Societies have utilized energy from manure for centuries. Collecting and burning biogas from liquid manure and collecting, drying, and burning solid manure are examples of traditional methods of using energy from manure. Recently developed technologies such as pyrolysis and exhaust-gas reburn can allow more efficient use of manure's potential energy.

For a general introduction to energy from manure see Saqib Mukhtar and Sergio Capareda, Manure to Energy: Understanding Processes, Principles and Jargon. Fact sheet E-428, Texas Cooperative Extension, Texas A&M University System. November, 2006. 4 pages.

How Do I Determine the Value of Manure as an Energy Source?

The value of energy from manure can be calculated as the quantity of energy and other goods and services produced multiplied by their respective prices minus the costs of the collected manure and of the goods and services consumed to produce the energy. Incentives are an important component of the economic feasibility of energy production from manure and should be included in the calculation. Some attributes of energy production from manure may be less tangible than others. Examples of less tangible outputs include farmer convenience, good will from neighbors, reduced risk, and environmental enhancement. When dollar values of less tangible attributes are not available, the prospective producer of energy from manure will have to assign personal estimates of value.

How Much Energy Does the Manure Contain?

An important step in evaluating manure to energy options is to assess the market value of the maximum energy potential of manure. This calculation includes the quantity and price of energy. One good way of evaluating manure's energy content is to compare it to the energy content of well known, widely used fuels such as diesel, coal or natural gas. The figure below shows that high-BTU manure harvested from cattle feedyard surfaces, for example, can compare favorably with low-quality coal (e. g., lignite) as a solid fuel in some cases.

Figure 1. The maximum recoverable fuel energy in different types of beef feedyard manure as compared to low- and high-quality coal products. (In Figure 1, "PC" refers to "partially composted" manure, corresponding to the kinds of manure in the two columns at far left.) Graph courtesy Dr. John Sweeten et al., 2006. View larger version of this image.

Figure 2. Maximum recoverable heating energy from manure as a function of moisture content and ash content. Chart courtesy Dr. Brent Auvermann, Texas AgriLife Research, Amarillo, TX. View larger version of this image

The maximum recoverable energy from manure products depends primarily on the water and ash content of the manure. Less ash and less moisture allow higher energy content. In the example illustrated in Figure 2, a utility company seeking long-term, high-quality, beef-feedyard manure to fuel its boilers had specified that the lowest quality manure it would accept would have a minimum HHV value of 2,758 BTU per lb (the blue line on the chart). Manure producers targeting higher fuel values of 3,500 BTU/lb (red line) or 4,500 BTU/lb (dark green line) can determine what combination of maximum moisture and ash contents would meet their objective. For example, a manure producer trying to achieve 4,500 BTU/lb could pick any point along the dark green curve (say, ash=30%, moisture=24%) and just meet the fuel-value objective. The purple triangle and orange diamond on the chart correspond to manure samples collected from two different cattle feedyards in the Texas Panhandle during 2002.

Ignoring differences in collection and handling costs and ignoring differences in co-product dispersal, the value of manure delivered to the power plant in this example could be calculated as the price of Texas lignite coal (e.g. $/ton) multiplied by the ratio of energy in the manure to the energy in the coal (e.g. 4500 BTU per pound of manure / 6143 BTU per pound of Texas lignite) to equal $ per ton of manure. In other words, since this source of manure has about 73 % of the heating energy of Texas lignite coal, it could be priced at 73% of the coal price.

Energy from manure may be produced on the farm or off the farm. Energy produced off the farm generally involves selling or transferring manure to a large processing facility. This transaction may be similar to selling manure off the farm for land application although the basis for valuing the manure is different (see the Business Arrangements for Manure Offsite Transfer page for more information). The farmer may evaluate the price received from the energy producer to the price available from land application, evaluate any differences in handling, storage, and transportation costs as well as intangibles and select the most attractive buyer or market.

Energy production on the farm usually requires an investment in facilities for processing manure to produce energy and to manage the co-product(s) of the process. Anaerobic digestion is the most widely used form of energy production from manure in the USA. The AgStar program supports capture and utilization of methane from livestock manure to produce energy. The AgStar program is sponsored by USEPA, USDA, and USDOE. http://www.epa.gov/agstar/index.html

Analysis of costs and returns of energy systems requires estimation of the quantities of energy and co-products that will be produced, their market value, the quantities of inputs required and their market values, and the values of incentives that are available for energy production. The AgStar program provides a handbook and computer program for preliminary analysis of anaerobic digestion systems to produce biogas and electricity on farms.

A variety of national and state level incentives exist for production of energy from manure. They include cost share programs such as EQIP, tax deductions and tax credits, marketable credits such as Carbon Credits and Green Energy Credits, and others. Lists of incentives can be found at the AgStar guide to state and federal resources and the Oregon http://egov.oregon.gov/ODA/energy.shtml

Proceed with caution and consider the next steps. Markets for energy from manure and technology for farm production of energy from manure are relatively new and developing in the U.S.A. Prices, costs, incentives, appropriate technology, and regulations may vary from one locality to the next and from one point In time to the next. Contact extension personnel and other experts, incentive providers, potential buyers, potential technology providers, other manure producers with experience producing energy, regulatory authorities, and other relevant sources of information in your location and develop your plan.

Additional Information

• LPE Learning Center webcast from September, 2007 Value of Manure in Energy Generation
• FAQ 27606 What factors should I consider to predict the effect of capturing energy from manure on my costs and profits?
  
• FAQ 27554 What is the difference between the "higher heating value" (HHV) and "lower heating value" (LHV) of a biomass fuel, and why is the difference important?
  
• FAQ 27543 How much fuel energy is contained in feedlot manure?
  
• FAQ 27557 What are typical values for the higher heating value of manure scraped from cattle feedyard surfaces?
  
• Bracmort, K and R. Burns. 2008. The Use of Anaerobic Digestion Systems to Mitigate Air Emissions from U.S. Livestock Production Facilities. Published in the proceedings of: Mitigating Air Emissions from Animal Feeding Operations Conference. Iowa State University.

Page authors: Kelly Zering, North Carolina State University and Brent Auvermann, Texas AgriLife Extension

Page reviewers: Kelsi Bracmort, NRCS and John D. Lawrence, Iowa State University