1. Agricultural Methane Recovery in Iowa
Presentation to the Region 7 Pollution Fall Roundtable
Presented by: David Downing, Energy Data Analyst
Energy and Waste Management Bureau,
Iowa Department of Natural Resources
October 2, 2002

2. Presentation Overview
Define anaerobic digestion
Current applications
Energy potential
Digester designs
System cost/benefits
Iowa Methane Energy Recovery Program
Iowa projects
Project incentives

3. Where Does Methane Gas Come From?
Methane is the principal component of natural gas. It is also a major element of biogas, or gas produced during the decomposition of organic materials in the absence of oxygen.
Anaerobic conditions occur in natural systems such as the bottom layers of wetlands and bogs, and in artificial systems like landfills, lagoons, and special designed tanks called anaerobic digesters.

4. What is a Methane Energy Recovery System?
Methane energy recovery involves capturing and harnessing the methane generated from the breakdown of livestock, landfill, or municipal waste to produce a usable form of energy, such as heat or electricity.

5. Current Iowa Methane Recovery Systems by Sector
Agriculture: Iowa has 5 livestock confinement operations that have methane digesters and recovery systems installed.
Landfills: Iowa has three landfill-gas-to-energy projects with a total electric-generating capacity of 7.5 megawatts.
Waste Water Treatment: At least 19 Iowa municipal wastewater treatment plants capture methane for on-site use and electric generation.

6. Energy Potential From Agricultural Waste
Each year Iowa’s livestock confinement operations produce 81 million tons of manure.
This amount has the potential to generate 2.8 billion kWh of electricity each year, equivalent to the energy consumed by 325,000 home annually.

7. Energy Potential From LFG
Each pound of organic waste generates two to six cubic feet of landfill gas.
Iowa has at least 12 candidate landfills, possessing an electricity generation potential of about 31 megawatts-the equivalent to powering 27,000 homes.
Emissions reductions equal removing 235,000 cars from Iowa roads.

8. Energy Potential From Iowa Wastewater
250,000 tons of municipal treated sludge is available each year for anaerobic digestion.
This waste has the potential to produce three trillion BTUs of energy each year.
Enough power to meet the electricity and heating needs of 24,000 Iowa homes annually.

9. Types of System Design
Most livestock confinement operations in the U.S. that utilize a methane digester and methane recovery system currently employ one of three basic types of anaerobic digester technology:
covered lagoon
plug flow
complete mix

10. System Components
A typical livestock waste anaerobic digestion system includes the following components:
Manure collection.
Anaerobic digester.
Gas handling.
Effluent storage.
Gas use.

11. Covered Lagoon System
Methane gas is captured by placing an impermeable floating cover over the manure lagoon.
The cover is sealed airtight by placing a weighted curtain on top of the cover material on the bank of the lagoon.
The biogas is collected by pulling the gas through a perforated pipe that has been inserted under the sealed cover and then sent to the end-use application

12. System advantages: System limitations: Least expensive to build.
Adaptable to a number of manure collection methods, including hydraulic flushing.
Construction and management is simple and straightforward.
System limitations:
Cannot be used in cold weather states because the digestion rate is dependent on temperature. Biogas production will vary by the season if the lagoon is not externally heated.
Because the manure in a covered lagoon system is not completely digested, odor is often released when the manure is land applied.

13. Plug Flow System
Usually rectangular in shape and built below ground level with an airtight cover.
Manure flows to a mixing tank where the percent of total solids can be adjusted by adding water. In order for the digester to operate efficiently, the manure needs to have a total solids content of 11 to 13 percent.
The contents of the mixing tank (the plug) are added daily, moving the older manure down the tank. The size of the tank is determined by number and size of daily plugs put into the digester, multiplied by the digester manure retention time of 15 to 20 days.

14. As manure is pushed through the system and the anaerobic process proceeds, biogas accumulates at the top of the digester tank. The biogas is pushed, by internal tank pressure or by pump, through a pipe located in the top 12'' of the tank to the end use area.
How much biogas is produced and the quality of the gas (methane content) is determined in part by the level of heat available in the digester tank and the nutrient level of the manure entering the digester.

15. Mechanical mixers are expensive.
The contents of the mixing tank (the plug) are added daily, moving the older manure down the tank. The size of the tank is determined by number and size of daily plugs put into the digester, multiplied by the digester manure retention time of 15 to 20 days.
As manure is pushed through the system and the anaerobic process proceeds, biogas accumulates at the top of the digester tank. The biogas is pushed, by internal tank pressure or by pump, through a pipe located in the top 12'' of the tank to the end use area.

16. System advantages: System limitations: Medium cost range.
Simple design.
Less labor intensive to operate.
System limitations:
Manure must have at least 6 percent solids content, with an optimal solids content of 11 percent.
This type of digester is compatible only with dairy scrape manure.
Requires a pre-mix tank.

17. Complete Mix Digester
Complete mix digester systems consist of an engineered tank, round or square, that is located above or below ground. The digester tank is covered with a fixed lid, most often made from poured concrete.
The process begins with manure being collected in the mixing pit either by a gravity-flow or a mechanical pump system.

18. A benefit of the complete mix system is that the digester can handle high manure volumes and use manure with solid contents ranging from 3 to 10 percent.
The manure is then sent to the reactor digester tank to be mixed, where a mechanical prop or blade system is used to keep the manure solids in suspension in the digester. This creates a homogenous substrate that prevents the formation of a crust on the surface. Retention time in the digester is usually between 10 to 20 days.

19. As the biogas builds at the top of the digester tank during the anaerobic process, the methane is removed from the digester by pipe and transported to the end use application.
Complete mix systems operate at either the mesophilic (20 degrees C to 45 degrees C) or thermophilic (45 degrees C to 60 degrees C) temperature ranges. The warmer the manure is in the mixing pit and digester, the shorter the retention time will be and the greater the biogas production.

20. System advantages: System limitations:
Can use slurry manure with a solid content of 3 to 10 percent.
Mechanical mixers keep solids from collecting on the bottom of the digester tank, delaying cleaning.
System limitations:
System requires additional maintenance.

21. System Cost
One of the barriers to expanding the use of anaerobic digesters and methane recovery systems is the overall cost of the system and subsequent slow rate of return on investment.
System costs have averaged $350,000 for a 700 cow dairy and $500,000 for a 5,000 head farrow-to-wean operation.
Engineering and design work has averaged $31,000 per system.

22. The cost of design and construction is often higher than other forms of construction because these systems are relatively new and have a number of unknowns. Few contractors or farm managers have practical experience in the design or construction of these systems. This often leads to cost overruns due to a trial-by-error approach.

23. Reasons for Cost Overruns
Owners and general contractors often hire the firms they trust and are familiar with, not the lowest bid.
Construction costs in rural areas vary greatly, particularly for material costs, such as lumber and concrete.
When contractors have to travel great distances to perform repeated tasks, costs for services escalate. This is particularly true for heavy equipment functions.

24. Benefits From a Methane Recovery System
Waste stream becomes a value added product.
Environmental benefits from reduced emissions.
Cost savings from generation agreement, possible future carbon credits.
Reduced odor levels. Odor abatement studies at livestock confinement facilities that operate anaerobic digesters and methane recovery systems have confirmed that odor levels are lower when compared to similar sized facilities with open lagoon systems.

25. Iowa Methane Energy Recovery Program
In 1998, the Department of Natural Resources formed an advisory committee to support the development of a Methane Energy Recovery Program. This committee of state and federal agencies, agricultural organizations, utilities and environmental groups recognizes the increasing importance of controlling odor, reducing the risk of pollution and offsetting fossil fuel consumption.
The goal of the program is to demonstrate and promote methane recovery at livestock confinements and other appropriate operations in Iowa.

26. Iowa Projects Top Deck Dairy Located near Westgate, in Fayette County.
700 cow dairy utilizes the 17,000 gallons of manure they produce daily to generate electricity.
A plug-flow digester.
150 hp engine with a 100kW generator and a 30kW Capstone microturbine to create 130 kilowatts of electricity.
Enough to power 20 homes daily.

27. The Top Deck dairy manure digester is the first in Iowa to put power on Iowa’s electrical grid, and is one of just 20 operating systems in the country. Power is available 24 hours each day for energy customers.
The final report for the Top Deck Dairy project is available on the Iowa Department of Natural Resources web site at:

28. Northeast Iowa Community College
150-cow Dairy Education and Applied Research Plug flow digester
Manure from the freestall barn is mechanically scraped to a reception pit.
Retention time is approximately 20 days.
Methane gas from the digester is used in a nearby boiler, with the hot water used to maintain the digester temperature and heat portions of the milking facilities during cold months.
Heat generation has been approximately 2.7 million Btu per day.
A solids separator has been installed and is being studied.

29. Bell Farms (formerly SWIne USA)
Located in Union County
5,000 head farrow-to-wean swine operation
Complete mix anaerobic digester
Engine generator that produces 60 kilowatts of electricity for use at the operation, 60 percent of the energy needed by the farm.
Waste heat from the engine generator is captured and used to heat the digester.
A detailed final report and contact information for the Bell Farms (SWIne USA) project can be found on the Iowa Department of Natural Resources Web site at:

30. Iowa Waste Characterization Study
Provides county level data on the amount of livestock waste in Iowa by animal type, numbers, and the energy potential of the entire waste stream.
Overview of the economics involved in the capture and use of methane from animal waste to generate electricity.
The study is available on the Iowa Department of Natural Resources web site at:

31. Iowa Methane Recovery Permit Requirements
Regulations for livestock confinement facilities vary, depending on the size of the facility, animal type and the number of animals housed.
Some operations may also require a manure management plan.
Jurisdiction for regulatory enforcement often falls under a combination of local and state governments.
If the methane recovery system involves putting electric generation into the local grid, a utility agreement will be necessary with the local utility.

32. Methane Energy Recovery Incentives
AgSTAR
Directed to show dairy and pork producers "how to
manage manure profitably while protecting the
environment.
For funding amount and application contact
AgSTAR.
AgSTAR
Department of Energy
Focused on biomass biorefinery for production of polymers and fuel.
Approximately $7.3 million will be awarded over the next 3-5 years.
For an application contact:
Chris Kielich
Great Lakes Regional Biomass Energy Program
Projects include the area of liquid biofuels and biomass power.
Funding amounts vary and usually require matching funds.
Applications are due in the spring.
Contact: Fred Kuzel, Director
35 East Wacker Drive, Suite 1850
Chicago, IL
USDA Rural Business Cooperative Program
Seeks to assist entities in rural areas to obtain loans for the purpose of improving the economic and environmental climate in rural communities, including initiatives for pollution abatement and control.
Funding ranges from $35,000 to $10 million for a total of $50 million.
Contact:
Alternative Energy Revolving Loan Program - Iowa Energy Center
The program provides low-interest loans to individuals and organizations who wish to build alternative energy production facilities in Iowa.
Low-interest loans for 50% of the total loan, up to a maximum of $250,000 will be awarded. Zero percent interest loan for half of financing costs associated with
project.
Application deadlines:October 31 and March 31 of each year.
Contact: Keith Kutz
Iowa Energy Center
2521 Elwood, Suite 124
Ames, IA
Iowa Environmental Protection Agency - Office of Wastewater Management "The Clean Water State Revolving Fund Program"
Previously the Construction Grants Program, this new, more flexible program, with control at the state level, has a wide variety of options, including funding of agriculture best management practices, and manure management and disposal.
Low interest loans, or other options such as: refinancing, purchasing, or guaranteeing local debt, and purchasing bond insurance.
Contact: Jeffrey R. Vonk, Director
Department of Natural Resources
502 E. Ninth Street
Des Moines, IA
Phone: (515)
Fax: (515)
Iowa Department of Natural Resources
Methane Gas Conversion Property Tax Exemption
Eligible technologies include alternative fuels.
Loan amount - 100% of the project. Applications shall be filed with the assessing authority not later than February 1 of each year for which the exemption is requested on
forms provided by the Department of Revenue and Finance.
Contact: David Downing
(515)
Methane EnergyReplacement Generation Tax Exemption.
This statute exempts electricity generated by methane gas conversion property from the replacement generation tax, which is six hundredths of a cent per kilowatt-hour.
Solid Waste Alternatives Program (SWAP)
The Solid Waste Alternatives Program (SWAP) funds the statewide
development and expansion of waste reduction and recycling projects.
First $20,000 is in the form of a forgivable loan, the next $150,000 is a zero-percent interest loan, anything more than $170,000 is a 3 percent interest loan. Pre-proposals are accepted year round and reviewed quarterly.
Contact: Valerie Drew
Iowa DNR - Waste Management
Assistance Division
(515)
p/index.htm
Value-Added Agricultural Products and Processes Financial
Assistance Program (VAAPFAP) - Iowa Renewable Fuel Fund
The State Loan Program offers a combination of forgivable and traditional
loans, with the interest rate typically the prime rate. Research and development
projects are not eligible for this program.
Funding amount is a combination of forgivable and traditional loans, with a maximum
of $525,000.
Contact: Joe Jones
Iowa Department of Economic
Development - Bureau of
Business Finance
(515)

33. Department of Energy
Focused on biomass biorefinery for production of
polymers and fuel.
Approximately $7.3 million will be awarded over the
next 3-5 years.
For an application contact:
Chris Kielich

34. Great Lakes Regional Biomass Energy Program
Projects include the area of liquid biofuels and
biomass power.
Funding amounts vary and usually require matching
funds.
Applications are due in the spring.
Contact: Fred Kuzel, Director
35 East Wacker Drive, Suite 1850
Chicago, IL

35. USDA Rural Business Cooperative Program
Seeks to assist entities in rural areas to obtain loans
for the purpose of improving the economic and
environmental climate in rural communities,
including initiatives for pollution abatement and
control.
Funding ranges from $35,000 to $10 million for a
total of $50 million.
Contact:

36. Alternative Energy Revolving Loan Program – Iowa
Energy Center
The program provides low-interest loans to
individuals and organizations who wish to build
alternative energy production facilities in Iowa.
Application deadlines:October 31 and March 31 of
each year.
Contact: Keith Kutz
Iowa Energy Center
2521 Elwood, Suite 124
Ames, IA

37. Iowa Department of Natural Resources
Methane Gas Conversion Property Tax Exemption
Eligible technologies include alternative fuels.
Loan amount - 100% of the project. Applications
shall be filed with the assessing authority not later
than February 1 of each year for which the
exemption is requested on forms provided by the
Department of Revenue and Finance.
Contact: David Downing
(515)

38. Solid Waste Alternatives Program (SWAP)
The Solid Waste Alternatives Program (SWAP)
funds the statewide development and expansion of
waste reduction and recycling projects.
Pre-proposals are accepted year round and
reviewed quarterly.
Contact: Valerie Drew
Iowa DNR - Waste Managementewwwww
Assistance Division
(515)
u/solidwaste/swap/index.htm

39. Value-Added Agricultural Products and
Processes Financial Assistance Program
(VAAPFAP) - Iowa Renewable Fuel Fund
The State Loan Program offers a combination
of forgivable and traditional loans, with the interest
rate typically the prime rate. Research and
development projects are not eligible for this
program. Funding amount is combination of
forgivable and traditional loans, with a maximum of
$525,000.
Contact: Joe Jones, Iowa Department of Economic
Development - Bureau of Business Finance
(515) ap

40. Iowa Department of Natural Resources
Methane Energy Replacement Generation Tax
Exemption.
This statute exempts electricity generated by
methane gas conversion property from the
replacement generation tax, which is six
hundredths of a cent per kilowatt-hour.
Contact: David Downing
(515)