Materials Characterization Paper In Support of the Proposed Rulemaking –
Identification of Nonhazardous Seco ndary Materials That Are Solid Waste
Biomass - Animal Manure and Gaseous Fuels

March 18, 2010

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1. Definitions of Animal Manure and Gaseous Fuels

In this context, we are defining animal manu re as the excrement of livestock reared in agricultural operations as well as straw, sawdus t, and other residues used as animal bedding.

Gaseous fuels may be derived fr om municipal and industrial landf ills (landfill gas) or from animal manure and solid biomass such as crop s ilage or the organic fraction of MSW (biogas). Both landfill gas and biogas are generated via anaerobic digestion, a multi-stage process whereby bacteria convert carbohydrates, fats, and proteins to methane (Evans 2001). EPA does not
consider these materials to be wastes in themse lves, when used as fuel, but rather materials
derived from wastes.

2. Annual Quantities of Animal Manure and Gaseous Fuels Generated and Used

(1) Sectors that Generate Animal Manure and Gaseous Fuels:

• NAICS 1121: Cattle Ranching and Farming

• NAICS 1122: Hog and Pig Farming

• NAICS 1123: Poultry and Egg Production

• NAICS 1124: Sheep and Goat Farming

• NAICS 112920: Horses and Other Equine Production

• NAICS 562212: Solid Waste Landfill

• NAICS 221320: Sewage Treatment Facilities

(2) Quantities and Prices of Animal Manure and Gaseous Fuels Generated:

• Domestic livestock production generates over a billion tons of manure annually. If all of this were used to produce biogas, it would yield approximately 19.4 million tons of methane (Cuéllar and Webber 2008). 1

• Anaerobic digestion of current manure production managed in ponds, anaerobic lagoons, and holding tanks would yield 2.4 million tons of methane. Current production is 0.07 million tons from 111 operating digesters (EPA 2008a).

• Around 35 million dry tons of current ma nure production could be used for bioenergy purposes once sustainability concerns are met ( e.g. , this manure is available after primary use of manure on so ils to maintain fertility) (Perlack et al

. 2005).

1 Biomass production estimates are presented on an annual basis.Biomass - Animal Manure and Gaseous Fuels

• In 2006, 11.4 million tons of landfill gas (3.0 million tons of methane) provided the equivalent of 150 trillion Btus for heat and electicity generation (EIA 2008).

• Current landfill gas production from 455 operational projects is 3.6 million tons of methane (EPA 2008b).

• A 2007 survey of anaerobic digestion syst ems at livestock facilities found an average biogas production cost of $6.60 per million btu (NRCS 2007).

• Poultry litter sold for electricity generati on at the Fibrominn LLC plant in Benson, MN, is purchased by contract with farmers at $3 to $5 per ton. The power helps meet a Minnesota legislative mandate for power generation from biomass, although it is not competitive with fossil fuels (Karnowski 2007).

(3) Trends in Generation of An imal Manure and Gaseous Fuels:

• Livestock production has become increasi ngly concentrated in recent years (Kellogg et al . 2000). This facilitates the collec tion of secondary materials for bioenergy purposes.

• Opportunities for utilizing animal byproducts for bioenergy production may increase in coming years with higher fo ssil fuel prices and improved conversion technologies including both biochemical and thermochemical platforms (Cantrell
et al. 2008).

3. Uses of Animal Manure and Gaseous Fuels

(1) Combustion Uses of Animal Manure and Gaseous Fuels:

• Biogas produced on farms is typically used to heat water for purposes of cleaning and sanitizing milking pipelines and e quipment in dairy operations (NRCS 2007). Note that this biogas is derived from animal products, and is not an animal product itself.

• An emerging market for animal manure is direct production of heat and power ( e.g. , the 55 megawatt Fibrominn LLC plant).

• In 2006, landfill gas was used by the follo wing sectors (energy basis): commercial (2.7 percent), industrial ( 49.3 percent), electric util ities (5.3 percent), and independent power producer s (42.7 percent) (EIA 2008).

• The combustor survey database devel oped by EPA for the 2009 proposal of the
Commercial and Industrial Solid Waste Incinerator (CISWI) standards and the Industrial Boilers Maximum Achievable Control Technology (MACT) standards includes one combustion unit that reporte d using approximat ely 416,000 tons of manure as fuel (EPA 2009). 2

, 3 The information in the database also indicates that units affected by these standards annua lly combust approximately 193,000 tons of

2 Although we report mature quantities from the combustion database as a tonnage, the database includes material quantities expressed in terms of heating values (B tu). To express this information as a tonnage, we assumed that manure has a heating value of 6,187 Btu per pound, which is the thermal value for chicken litter reported by Wright (Wright et al. 2006).

3 The categories of material in the combustion data base that we assume are manure are (1) poultry litter and (2) manure.

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biogas and 3.4 million tons of material desc ribed in general terms as biomass or bio-liquids. 4

(2) Non-Combustion Uses of Anim al Manure and Gaseous Fuels:

• Animal manure is spread on cropland and pa stureland as a fertilizer to replenish
nutrients and as a soil treatment to improve soil quality by enhancing soil structure and increasing the soil’s ability to hold water and resist compaction (Kellogg et al. 2000). Other uses are uncommon in the US ( e.g. , home heating, cooking, and paper production).

(3) Quantities of Animal Manure and Gaseous Fuels Landfilled:

• The amount of animal manure landf illed has not been identified.

• An additional 535 candidate landfills have been identified with the potential to provide 2.4 million tons of methane (E PA 2008b). Milbrandt (2005) estimated total domestic production from landfills an d domestic wastewater treatment sites at 13.6 and 0.5 million tons of methane, respectively.

(4) Quantities of Animal Manure and Gaseous Fuels Stockpiled/Stored:

• Information about quantities of anim al manure stockpiled are unknown. While the quantity of animal manure undergoing s hort-term storage is significant, decay rates and issues associated with storag e (leaks and odor), along with technical limitations associated with storage of gases likely place some limits on stockpiling activity, particular ly because the value of these materials is not likely to appreciate as the resu lt of long-term stockpiling.

Exhibit 1: Overview of Generation and Use of Animal Manure and Gaseous Fuels

Annual Quantity Used
as Fuel Annual Quantity
Generated Cement
Kilns Other Additional
Annual Quantity Annual Quantity in
Other Uses Total Quantity Stockpiled as
of 2008 Commodity

----------- million tons of met hane per year ----------- Biogas from Agricultural
Anaerobic Digesters 0.07 N/I 0.07 N/I N/I N/I

Landfill Gas 3.60 N/I 3.60 2.4 – 10.0 N/I N/I

N/I = not identified

4 To convert the total Btu values reported for biogas to a tonnage, we assumed a thermal value of 11,820 Btu/lb (EIA 2008). To convert the total Btu values reported for general biomass and bio-liquids to tonnages, we assumed a thermal value of 6,000 Btu/lb for this material, based on the range of thermal values reported for biomass materials in this paper, the food scraps and agricultural residue materials characterization paper, and the materials characterization paper for forest derived biomass and pulp and paper residues.

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4. Management and Combustion Processes for Animal Manure and Gaseous Fuels

(1) Types of Units Using Animal Manure and Gaseous Fuels:

• Biogas generated on farms is typically co mbusted directly in boilers and to a lesser extent is burned for space heating (NRCS 2007).

• Landfill gas is used to generate electricity in internal combustion engines, gas turbines, and microturbines. It also ha s direct use appli cations in boilers, combined heat and power systems, drye rs, kilns, and greenhouses (EPA 2008d).

(2) Sourcing of Animal Manure and Gaseous Fuels:

• Manure is generated in all livestock ope rations. Anaerobic di gesters for biogas production accommodate manure handled as a liquid, slurry, or semi-solid ( i.e.

, total solids up to approximately 12 percent) (EPA 2002).

• Landfill gas forms as a by-product of manure decomposition.

(3) Processing of Animal Manure and Gaseous Fuels:

• Biogas generated on farms is typically co mbusted on-site with little upgrading other than hydrogen sulfide and moisture removal. Carbon dioxide may also be removed for applications where high th ermal values are needed (NRCS 2007).

• Landfill gas also needs to undergo mini mal upgrading when used in most applications (EPA 2000). Substantial upgrading is needed, however, should landfill gas be introduced into natural gas distribution networks. Here a series of membrane separation processes, molecula r sieves, and absorption processes are employed (CCTP 2005).

• Public comments submitted to EPA in response to the Advanced Notice of Proposed Rulemaking (ANPRM) suggest that manure is not typi cally treated to eliminate potentially harmful components be fore being applied to crop fields or stored (Werber 2009).

(4) State Status of Animal Ma nure and Gaseous Fuels:

• At this stage, we have not identified any states that have specifically granted a beneficial use designation for the use of animal manure as fuel, but we have not performed an exhaustive investigation of state activities and regulations. For example, it is possible that equivalent de signations are made by states as part of agricultural regulation. 5

• As of September 2006, approximately 50 pe rcent of states had renewable fuels portfolio standards requiring that varying percentages of power generated within
the individual states come from alte rnative fuels (including biomass) by a designated future date; several more stat es have enacted such regulations since

5 Although we identified no states with a beneficial use designation for the use of animal manure as a fuel, public comments submitted in response to the ANPRM indicate that there are ongoing studies to determine the feasibility of using animal waste product, specifically chicken manure or “chicken litter” as a fuel for cement kilns (Elliott 2009).

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then (DOE 2006). 6 For instance, in August 2007, No rth Carolina enacted a law to “promote the development or renewa ble energy...through implementation of a renewable energy and energy efficiency por tfolio standard (REPS)” (Session Law 2007-397. This law specifically calls for the following:

Sec. 62-133.7 (e). Compliance with REPS requirement through
use of swine waste resources. -- For calendar year 2018 and for each calendar year thereafter, at least two-tenths of one percent (0.2%) of the total electric power in kilowatt hours sold to retail electric customers in the State shall be supplied, or contracted for supply in each year, by swine wa ste. [Interim percentages are mandated for 2012 and 2015.]

Sec 62.133.7(f). Compliance with REPS requirement through use of poultry waste resources. -- For calendar year 2014 and for each calendar year thereafter, at least 900,000 megawatt hours of the total electric power sold to reta il electric customers in the State shall be supplied, or contracted fo r supply in each y ear, by poultry
waste combined with wood shavin gs, rice hulls, or other bedding material. [Interim megawatt hour values are mandated for 2012 and 2013.]

5. Animal Manure and Gaseous Fuels Composition and Impacts

(1) Composition of Animal Manure and Gaseous Fuels:

• Biogas from on-farm anaerobic digester s typically contains 60 to 70 percent methane and 30 to 40 percent carbon di oxide by volume (NRCS 2007). Landfill gas tends to contain between 45 to 55 percent methane and 45 to 55 percent carbon dioxide (Messics 2001). Average low heat values of gaseous fuels are approximately 19,840 btu/lb for methane, 11,820 for biogas, and 6,500 for landfill gas (EIA 2008).

• Poultry litter has a high heat value of 6,187 btu/lb (Wright et al. 2006).

• Public comments submitted by the Environm ental Integrity Project in response to the ANPRM maintain that all concentrated animal feeding operations (CAFO) waste contains heavy metals, halogens , dioxins, and other hazardous compounds (Werber 2009).

6 The summary table in the referen ce does not always specify which types of biomass are included, however, some examples specific to animal manure and gaseous fuels include: Maryland specifies “poultry litter incineration”; Nevada specifies “biomass (includes...animal waste...)”; and New Mexico specifies “animal waste” in
the definition of “biomass resources”. Other states use th e term “sustainable biomass” which could include animal manure/gaseous fuels, while others may include animal manure/gaseous fuels in the generic term “biomass”.

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(2) Impacts of Animal Manure and Gaseous Fuels Use:

• Benefits include 1) energy use of methan e, a greenhouse gas, otherwise released to the atmosphere (EPA 2008e), 2) displa cement of fossil fuels, primarily natural gas, and, 3) potential reduction of pollu tants harmful to human health (NRC 2003).

• Landfill gas emissions vary considerably depending on the composition of the waste in the landfill, the efficiency with which gas is captured, and the pollution control technologies used in combustion. Combustion of landfill gas for energy leads to reductions in greenhouse gase s, VOCs, and organic mercury compounds
relative to uncontrolled emissions from landfills (EPA 2008f). In addition, combustion of landfill gas avoids the impacts associated with extraction, processing, and transportation of typical primary fuels like natural gas. The emissions and upstream impacts associat ed with natural gas combustion are
identified in Exhibit 2.

• Fermentation of pig manure to create bi ogas has been shown to reduce nitrous oxide by 14 grams per ton of manure comp ared to typical storage and fertilizer applications (Nielsen 2002).

• In addition to the avoided GHG emissions, combustion of biogas as a replacement for natural gas avoids the emissions asso ciated with the extraction and processing of natural gas. Exhibit 2 lists the emi ssions from combustion of biogas from a typical pig farm and combustion and pre- combustion processing of natural gas at a typical industrial boiler in the U.S. in the late 1990s. Note that the emissions of many of the criteria pollutants are si milar to natural gas combustion, but significant reductions are achieved by a voiding the impacts associated with extraction and processing of natural gas.

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Exhibit 2: Comparative Emissions of Biogas and Natural Gas Combustion

Biogas Natural Gas

Combustion Combustion Combustion plus Upstream Pollutant

----- Lb./MMBtu -----

Criteria Pollutants

PM2.5 0.003
- - PM10 0.003 0.009 0.009
PM, unspecified
- - 0.004

NOx 0.072 0.301 0.417

VOCs 0.009 0.009 0.524

SOx 0.026 0.073 1.985

CO 0.084 0.058 0.282

Pb
- - 2.72x10 -7

Hg
- - 7.18x10 -8

Greenhouse Gases

CO 2 194.5 114.6 129.8

CH 4 0.009 0.003 0.372

N 2 O 0.005
- 1.17x10 -5

MTCO 2 E/MMBtu 0.089 0.052 0.062

Sources: Franklin Associates 1998; Nielson 2002.
Notes: “-” signifies data not available; may equal zero. Emissions of biogas reflect combustion process only and do not include upst ream, downstream, or avoided impacts.

The emission information presented in this table is derived from Life Cycle Inventory (LCI) data, as compiled by Franklin Associates. LCI data identifies and quantifies resource inputs, energy requirements, and releases to the air, water, and land for each step in the manufacture of a product or process, from the extraction of the raw materials to ultimate disposal. The LCI can be used to identify those system components or life cycle steps that are the main contributors to envir onmental burdens such as energy use, solid waste, and atmospheric and waterborne emissi ons. Uncertainty in an LCI is due to the cumulative effects of input uncertainties and data variability.

There are several life cycle inventory databases available in the U.S. and Europe. For this paper, we applied the most readily available LCI database that was most consistent with
the materials and uses examined. These LCI data rely on system boundaries as defined by Franklin Associates, as described in the documentation for this database, available at: http://www.pre.nl/download/manuals /DatabaseManualFranklinUS98.pdf

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