Methane as a Greenhouse Gas (GHG)

Methane is responsible for about 18% of the enhanced greenhouse effect'. According to the Intergovernmental Panel on Climate Change, methane concentrations now are at their highest levels in 420 000 years2. Although there is considerably less methane than carbon dioxide in the atmosphere, it is a serious problem. Methane is 21 times more effective at trapping heat than carbon dioxide.

GHG's and the Hog Industry

Manure in storage and on land is a significant source of methane emissions. When manure decomposes in the absence of oxygen (anaerobic), much of it is converted to methane gas. When oxygen is present (aerobic), decomposing manure releases nitrous oxide, another potent GHG.

Manitoba's livestock industry in growing. The sale of Manitoban hogs increased from 4.3 million to 5.3 million head from 1999 to 2000. A full-grown pig produces 4.5 kg or 10 Ibs of manure a day. Projects to reduce emissions from hog manure offer a considerable opportunity to start meeting GHG reduction commitments under the Kyoto Protocol.
At the "Greenhouse Gases and the Hog Industry" workshop (December 9, 2002), the Canadian Pork Council (CPC), along with participants from pork and farm associations; federal and provincial departments of agriculture, environment and natural resources; agrologist institutes; research centres and Chairs of pork-related congresses identified priorities in the development and application of GHG reduction technologies for the pork sector. They include 3:

· Projects should consider whole farm applications
· Projects should be applicable to small and large scale farming operations
· There is a need to focus on handling, storing, and covering manure
· Demonstrations for N use efficiency anaerobic digesters were recommended.

Anaerobic Digestion
Biogas recovery systems have been identified as one of the most promising areas of development for the significant reduction greenhouses gas emissions from agriculture. Biogas recovery systems are also known as anaerobic digesters.
During anaerobic digestion, microorganisms break down manure in an oxygen-free environment. One of the natural products of this process is biogas. Biogas typically consists of 60 to 70 percent methane, 30 to 40 percent carbon dioxide and trace

 

1 Kinsmen, R.G., F.D. Sauer, H.A. Jackson, H.K. Patni, D.I. Masse, M. Wolynetz and J.A. Munroe. 1997. Methane and carbon dioxide emissions from lactating Holsteins. Dairy and Research Report, Centre for Food and Animal Research, AAFC.
Z Jouzel, J. and D. Raynaud. 1999. COa and Temperature over the Last 420,000 Years: Present and Projected Climate Changes in Perspective. USGCRP Seminar. http://www.usgcrp.gov/usgcrp/seminars/990923FO.html.
3 Canadian Pork Council. 2002. Green House Gases and the Hog Industry. Workshop Proceedings, Dec.9 2002.

 

amounts of other gases4. Depending on digester design, methane content can reach as a high as 95%.
Benefits of Biocias Recovery
Captured biogas can be used to generate heat, hot water or electricity. As such, recovery systems significantly reduce energy costs for both private and commercial operations. As such, the use of biogas recovery systems fits with AAFC's Sustainable Development Strategy: "by 2006, there will be an increase in the ratio of agricultural output energy over input energy"5.
Biogas can also be flared to control odour if energy recovery is not feasible. Both flaring and energy production reduce greenhouse gas emissions.
Other benefits to biogas recovery include:
· Odour control - the effluent odour from anaerobic digesters is significantly less than odours from conventional manure management systems. Odour reductions of 98 percent have been achieved by pilot digester projectsb.
· Water quality protection - when digesters are properly managed, phosphorous and metals settle out. When processed manure is applied to the land, these elements are left behind, keeping them out of surface waters. Digesters are also made of concrete or steel, protecting water from pollution with pre-treated manure.
· Public health protection - heated digesters isolate and destroy disease-causing organisms that might otherwise contaminate surface waters and pose a public health risk.
· High quality endproducts - anaerobic digesters reduce ammonia losses. Digested manure can contain more valuable nitrogen for crop production.
System Desiqn
Biogas recovery systems have four basic components: a digester, a gas-handling system, a gas-use device and a manure storage tank or pond to hold the treated effluent prior to land application. Digesters can effectively process manure in 2-3 days or 25-30 days', depending on the technology used. There are three types of digesters:
· A complete mix digester is a heated tank of either reinforced steel or concrete, with a gas-tight cover. The contents are mixed periodically by a motor-driven impeller or a pump. This type works best with slurry manure (typical of hog operations) with total solids content between 3 and 10 percent.
· A covered lagoon digester is an earthen lagoon fitted with a cover that collects biogas as it is produced. They are best suited for manure collection systems with

4 EPA. 2002. Managing Manure with Biogas Recovery Systems: Improved Performance at Competitive Costs. The AgSTAR Program. Office of Air and Radiation (6202J). EPA-430-F-02-004. www.epa.gov.
5 AAFC. 2001. Agriculture in Harmony with Nature: AAFC Sustainable Development Strategy II, 2001-2004. Publication 2074/E. http://www.agr.ca/policy/environment.
6 Zhang, Q. 2002. Odour Test Report. In Field Test Demonstration of SEI Hog Manure Treatment Technology: Final Report. G. Lakshman. Pp 14-16.
7 ONR Environmental Systems. 2002. ONR Agri-Design: Anaerobic Digester Technology. ONR Product Information Sheet Rev.OlAND, http://www.onrsystems.com

 

very low solids content. Because they are not heated, they do not produce adequate biogas flow for energy production during colder months.
· A plug-flow digester is a long, narrow heated tank - often built below ground level - with a gas-tight cover. They are used only for dairy manure, and require thick manure ranging from 11 to 13 percent solids. As this design is not relevant to hog operations, it will not be discussed in subsequent sections.

Biogas Recovery System Costs
Cost depends on the size of the operation. The larger the operation, the lower the per unit cost of the biogas recovery system. The Environmental Protection Agency suggests a break-even herd size of 2500 hogs for a complete mix digester, and 1350 hogs for a covered lagoon digestera.
On a per unit basis, heated digesters cost approximately $200-420 CDN per hog and covered lagoon digesters cost $200 - 400 CDN per hog'. Biogas recovery systems have a payback period of 3 to 7 years when biogas products are used for energy production.

Canadian Technology Providers
There are currently three Canadian companies that design/build biogas recovery systems, provide technology, and offer consulting services:

ONR Environmental Systems Inc.
Site 17, Box 2, RR 1
Okatoks, AB T1S lAl
Ph: 403-540-6541 Fx: 403-938-2715 e-mail: info@onrsystems.com

Clear-Green Biotechnologies Inc.
13-1724 Quebec Avenue Saskatoon, SK
S7K 1V9
Ph: 306-931-2610 Fx: 306-931-6610 e-mail: benvn@clear-green.com

RENTEC Renewable Technologies, Inc.
342 English Settlement Road
Trenton, On K8V 5P7
Ph : 613-849-9199 Fx: 613-475-0361 e-mail: info@rentec.ca

 

 

 

e EPA. 1997. AgSTAR FarmWare Software, Version 2.0. FarmWare User's Manual. http://www.epa.gov.methane/home.nsf/pages/agstar.
9 EPA. 1999. Final Report on U.S. Methane Emissions 1990-2020: Inventories, Projections and Opportunities for Reductions. Section 5. EPA-430-R-99-013.

 

 

For additional Canadian and international technology providers, digester information and an inventory of manure digester programs and projects, visit: http://res2.agr.ca/initiatives/manurenet/en/man digesters.html.

Funding Opportunities
Canadian Pork Council
1101-75 Albert Street Ottawa, ON
K1P 5E7
Ph : 613-236-9239
Fx: 613-236-6658
www.cpc-ccp.com

Approximately $623 000 per year will be available for the hog industry from 2003 to 2006 (3 years). The CPC has issued calls for proposals for activities that will assist in the adoption of new practices or technologies by farmers to address greenhouse gas emissions.
The Canadian Adaptation and Rural Development Fund (CARD)
Dr. Les Haley, Chair
Climate Change Funding Initiative in Agriculture Canadian Agri-Food Research Council
Building 60, Central Experimental Farm
Ottawa, ON
K1A OC6
or
Bob Zidichouski
Agriculture and Agrifood Canada
930 Carling Avenue, Room 481
Ottawa, ON
Ph: 613-759-7219
Fx: 613-759-7490
www.agr.ca/policy/adapt/national_initiatives/climatechange.phtml.

The Climate Change Funding Initiative (CCFI) is a four-year, $4 million investment to help the agricultural sector address climate change and ultimately help contribute to Canada's efforts to meet its Kyoto commitments to reduce GHG emissions to six percent below 1990 levels by 2008-2012. research and development areas include manure management, carbon sequestrations and biofuels.

Biogas Recovery - A Scalable Technology
Biogas recovery technologies have applications beyond the barn. In Kristianstad, Sweden, biogas plants are used to co-digest municipal solid waste with manure and other organic biomass for the production of energy and fertilizer. The project offers a feasible and sustainable solution to waste problems in many countries.
Program highlights10:
10 CADDET Centre for Renewable Energy. 2000. Co-Digestion of Manure with Industrial and Household Waste. Technical Brochure No. 118. http://www.caddet-re.org.
· Built on the site of a closed-down sugar beet factory, tanks from the former sugar wastewater treatment plant are re-used as digestion and storage tanks. Kristianstaders separate their organic waste into paper bags, which are collected by municipal services. In 1998, 3100 tonnes of household waste was collected and digested from 100 000 households.
· Industrial waste is also processed at a cost of approximately $65/tonne (CDN). A total of 41 200 tonnes of manure (hog, cattle and poultry), 24 600 tonnes of abattoir waste and 900 tonnes of distillery waste was processed by the municipal digester in 1998.
· Gross biogas recovery for 1998 was 20 000 MWh. 2 100 MWh were used to heat the digester. 17 900 MWh were sold to the district heating plant.

This type of technology may be appropriate for small municipalities whose landfills are not large enough support a methane recovery operation. It also reduces the amount of waste that enters landfills.

Monday, November 17th, 2003

 

Turning hog manure into heat

Manitoba urged to investigate Saskatchewan system

Monday, November 17th, 2003

By Leah Janzen

ENVIRONMENTALISTS say Manitoba should investigate a new method that turns hog manure into a valuable source of power.

The system, developed by a Saskatchewan company, takes the smell and dangerous chemicals out of hog manure and can eventually turn the waste into heat and power for homes.

"These new approaches need to be tried or the industry will find itself very unwelcome in the province,'' said Fred Tait, a member of Hogwatch Manitoba. "Its future viability is at stake.''

There are about 1,668 commercial hog operations in the province producing about four million animals a year and adding about $900 million to the economy.

But nearly every time a new intensive livestock operation is proposed in Manitoba, opponents argue against it, citing noxious odours, dangerous runoff from manure spreading and water contamination.

Clear-Green Environmental Inc., a Saskatoon company, says it can deal with those concerns and then some.

The company is in the process of building a $1.5- million demonstration facility north of Saskatoon in collaboration with SaskPower to showcase the technology it says will make hog production safe and clean and will provide a new power source for hundreds of homes in the province.

The system takes manure directly from the hog barn to a large tank -- eliminating the need to dig manure lagoons for storage.

Once inside the tank, the manure is heated to encourage development of bacteria. The bacteria digests the organic matter in the manure, producing methane gas -- which is similar to natural gas.

That methane gas can be converted into heat and power.

Nitrogen, phosphorus and potassium -- chemicals in the manure which have been blamed for polluting lakes, rivers and wells -- are broken down, purified and sold as fertilizer.

All that's left after the process is complete, said Clear-Green Environmental president Ben Voss, is water. The technology shows so much promise that SaskPower has signed on as a partner.

Larry Christie, a SaskPower spokesman, said the utility has invested $500,000 for four micro-turbines for the project which will convert the gas into heat and energy.

Early estimates suggest the average farm -- with about 2,500 animals -- will produce enough gas to provide electricity to 100 homes.

Voss concedes the technology is expensive, but he said the system won't cost farmers any more.

He said Clear-Green will pay to construct and operate the plants. Farmers will pay a small amount to Clear-Green to convert their manure. Heat generated by the system will be provided to the farm to heat the barns.

Tait said he'd like to see the Manitoba government establish a similar project.

Manitoba Hydro spokesman Jim Peters said the utility has not been approached by Clear-Green officials, but would be interested in speaking to the company about the technology and its possible applications for Manitoba.

"All of these alternative energy sources are of interest to us,'' he said.

leah.janzen@freepress.mb.ca

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