420 likes | 551 Views
Manure – A Multi-Purpose Resource : ”Things are Changing in the Barnyard!”. Bruce T. Bowman Expert Committee on Manure Management Canadian Agri-Food Research Council London, ON Presented to: Nova Scotia Soil & Crop Improvement Association February 22, 2005. Presentation Outline.
E N D
Manure – A Multi-Purpose Resource:”Things are Changing in the Barnyard!” Bruce T. BowmanExpert Committee on Manure Management Canadian Agri-Food Research Council London, ON Presented to: Nova Scotia Soil & Crop Improvement Association February 22, 2005
Presentation Outline • Conserving and Recycling Manure Nutrients • Relevance and links to manure processing • Manure Processing – Anaerobic Digestion • Renewable Energy & Livestock Farming • New Opportunities – rural revitalization, diversification, and energy independence • Micro CHP distributed power generation
Manure ManagementPriority Issues Three priority issues to manage: • Nutrients • Odours • Pathogens............................. but also……. • Water volumes • Carbon = Energy $$$ Context:Presentation will be more applicable for larger confined livestock operations than for grazing-based systems.
Conserving Nutrients:Gaseous Nitrogen losses from Manure • Two major loss pathways: • As volatile ammonia (NH3) • As nitrous oxide (N2O) (greatest impact of GHGs – 310x effect of CO2) • Gaseous losses can occur at any stage of handling with continued exposure to air.
Conserving Nutrients:Ammonia losses from Manure • pH 9.4 [NH3] / [NH4+] = 0.50 (50%) @(20°C)pH 7.5 [NH3] / [NH4+] = 0.018 (1.8%)pH 7.0 [NH3] / [NH4+] = 0.0056 (0.56%)Keep pH near 7 (neutrality) to minimize NH3 losses • Ammonium (NH4+)- non-volatile; Ammonia (NH3)- volatile • Ammonia losses are also rapid from bare floors; Remove manure when fresh to closed storage to minimize NH3 losses.
Conserving Nutrients:Ammonia losses from Manure • Why should we minimize these losses? • Increasing replacement costs for commercial N = $$$- Urea production energy intensive + GHG emissions • Ammonia emissions receiving more scrutiny from both animal and human health perspectives(smog potential – lower Fraser Valley in BC) • Ammonia - a toxic substance under CEPA (Can. Env. Protection Act) • Secondary source for nitrous oxide (N2O) production.
Conserving Nutrients:Nitrous Oxide Production Nitrification Oxidation ammonium nitrate Denitrification Nitrification & denitrification are biological processes 30° - 40°C Reduction** nitrogen gas nitrate
Conserving Nutrients:Reducing Nitrous Oxide Emissions • Maintain aerating conditions - in manure storage & handling, or in soil following land application.(e.g. avoid application on saturated soils – restricted aeration; • Reduce Exposure to Air in Storage- negative air pressure covers on lagoons reduce gaseous losses. • Reduce “labile carbon” content in manure(energy source for microbes)– 50% of carbon in digested manure is converted into biogas, depriving soil microbes of this energy source following soil application less N2O production.(minimal negative impacts on soil quality)
Trends in the Fertilizer Industry-- Post WWII (1945) -- • Cheap & plentiful mineral fertilizers helped spur intensification and specialization in production agriculture after 1945. • Cereal production (cash-cropping) is often separate from livestock production, relying only on mineral fertilizers.(Mixed farming systems are usually more sustainable). • Started to create some regional nutrient surpluses(Quebec, North Carolina, Chesapeake Bay area). • Consequence:Nutrients in livestock manures originating from imported feeds - not recycled back to source for next cash-crop production cycle.
Food Products Human Consumption Cereal Production Nutrients O.M. Manure Wastes Local Farm Landfills LARGE-SCALE NUTRIENT FLOWS Recycling Nutrients & Organic Matter Nutrient inputs Annual Mineral Fertilizer Additions Nutrients & O.M. NOT recycled Regional nutrient excesses
Reasons to Recycle Livestock Nutrients • Many confined livestock operations import more nutrients than they export, resulting in nutrient accumulations.(US studies - NE, WA, PA) … not sustainable in long term. • Can not continue to increase N loadings and still maintain current nitrate water quality standards. • Human activities doubled global N fixation rate in 20th century. • In many countries, P is considered a non-renewable resource – finite supply, some of which have high heavy metal contents (e.g. Cd in phosphate from Idaho).
Whole Farm Nutrient Balances(Budgets) • Balancing Nutrient INPUTS & OUTPUTSat farm-scale or at small watershed-scale.– Next stage in Nutrient Management Planning & Source Water Protection. • As more precise nutrient management planning is implemented, many farmers will discover nutrient surpluses somewhere within their land base. • Recent Studies in U.S.A. show that majority of farms studied have nutrient surpluses,esp. Nitrogen. (INPUT/OUTPUT > 1.5)(Koelsch & Lesoing, 1999; Cogger, 1999)
Managing On-Farm Nutrient Surpluses • Three Options(singly or in combination) • Reduce nutrient inputsto balance nutrient exports from the land base(e.g. improved feeding strategies – nutrient use efficiency e.g. phytase). • Increase land basefor applying manure nutrients (buy, rent more land or contract for exporting excess manure;Exporting liquid manure nutrients < 15 km radius (economics). • Export surplus nutrientsfrom the farm in the form of value-added products(new revenue - organic fertilizers/amendments).
Requirements for Exporting Surplus Livestock Nutrients • The need to export surplus nutrients will increase with further intensification of livestock operations. • Criteria for exporting manure nutrients: • Odour-free • Pathogen-free • Dewatered (dried) for transportation Manure processing can address these issues.
What is Manure Processing? • ….“Treating” the entire manure volume to reduce odours & pathogens.Two best technologies: • Anaerobic digestion – high cost, greater revenue • Composting– low-cost, limited revenue • Manure processing can provide the farmer withincreased flexibilityfor managing surplus nutrients, while solving other environmental problems.
Economic Renewable energy generation- energy independence Export surplus Livestock nutrients Emission reduction trading credits Tipping fees – food-grade wastes - 20 – 25% energy boost Environmental Reduce odours & pathogens- flexibility to export surplus nutrients Conserve nutrients (N)- reduce mineral fertilizer use Reduce emissions- GHGs & ammonia Why Digest Manure?Potential Benefits Societal • Reduce siting / zoning problemsRegain public support • Opportunity for new rural partnerships
Yield / Productivity Environmental Protection Societal Concerns Balancing Issuesin a Sustainable Farming Operation • 1. Yield/Productivity (economics)2. Environmental Protection • Both are science-based Pre-1965 Since 1970s 2-D • 3.Societal Concerns • Perception-based, emotional • Can over-ride other 2 factors. • Opposition difficult to reverse once initiated Since 1990s 3-D
Anaerobic DigestionA Few Facts • Mimicking fermentation in a ruminant stomach.(most digesters are mesophylic ~ 37°C – body temp.) • Kills weed seeds – reduces herbicide use. • pH often increases about 0.5 unit during digestion. • Closed system– no nutrient or gaseous losses (e.g. N) - closer N:P ratio than with raw manure • About 50% of carbon biogas(CH4 + CO2, 65:35, tr. H2S)- (nutrients in more plant available, predictable form)
Anaerobic Digestion…….. More Facts • Certain antibiotics can HALT digestion processes • Solids range: up to ~ 13%(easily pumpable) • Hydraulic Retention Time:(processing time):- 20–35 days @ 37°C • Odour Reduction:~ 90 % or more • Pathogens Reduced to:~ 1/1000 – 1/10,000 (mesophylic);- Eliminate pathogens by pasteurizing (1hr @ 70°C)
Managing Dead StockA Waste + Nutrient Issue • Currently a waste issue that costs the farmer to manage – end products have lost their value since BSE crisis - can’t recycle animal protein through feed system – e.g. bonemeal has lost much of its value • Current disposal methods have limitations • Burial – limited capacity, point source pollution potential • Incineration – N and C lost, minerals?; emission issues renewable energy recovery possible • Composting – cost recovery for composted solids
Managing Dead StockA Waste + Nutrient Issue • Anaerobic Digestion – best solution for deadstock and for animal rendering – 2 valuable end products • Renewable energy recovery (heat, electricity) • Organic fertilizer/amendment end product • Conserves N, P & some C for recycling back to land • Minimizes odour problems; eliminates pathogens • Pre-treatment = shredder + Pressure/Temperature- treated waste virtually all digestible - possible elimination of BSE prions
Types of Anaerobic Digesters Courtesy of: US EPA AgStar Handbook
Components of a Complete Mix Mesophillic Digester Hydraulic reactor Buffer tank - Premix Remove foreign materials Combined Gas + Effluent Storage Co-Gen Set Grid Courtesy:Rentec Renewable Technologies
Manure ProcessingAnaerobic Digestion • Low Tech • High Tech
Barriers to Adoptionof Anaerobic Digesters • Initial Investment / Payback Issues • Regulatory Issues • Reliability, Trust & Expertise • Managing Complexity
Overcoming Barriers to Adoption of Anaerobic Digesters • Initial Investment / Payback Opportunities • $300K - $5M, depending on scale of operation– Plant Life = 20 – 30 yr – Payback = <10 yr (electricity, solids sales, emission credits) • Policy changes - Environmental Loan Guarantees & Tax Incentives– to assist farmer in managing initial capital risks • Payback - What is the value of odour/pathogen-free manure products to the farmer?– change from societal opposition to support (partnerships)
Overcoming Barriers to Adoption of Anaerobic Digesters • Potential Revenue Streams • Electricity Purchase Agreements– Net Metering, Dual Metering – Peak Demand Generation– Nova Scotia, Ontario, Saskatchewan - leading provinces– may be sufficient to be energy independent; delivered power ~ 2 x generating costs (ON = 12 - 15¢/kwh) • Sale of Processed Solids/ Org. Fertilizers– excess nutrients exported – promotes nutrient re-use • Emission Trading System currently developing- sell credits for reducing emissions- current value of e-CO2 ~ $10/tonne • Tipping Fees for Receiving Food-Grade Wastes– boost biogas output (20 – 30%) increases revenue
Overcoming Barriers to Adoption of Anaerobic Digesters • Regulatory Issues • Electrical generation– interconnects / net meteringPower Utilities starting to change policies for small renewable energy generators (up to 500 kw) • Off-farm biomass inputs(boost biogas production)can result in C. of A.s – regulations being changed to allow <20% food-grade wastes • Managing emissions / dischargesBiogas flare, potential ghg, or liquid discharges • Fertilizer/amendment products(quality, certification)– labeling requirements
OvercomingBarriers to Adoptionof Anaerobic Digesters • Reliability, Trust & Expertise • Small installed digester base in Canada(12 – 18 in advanced design or already built) • Limited knowledgeable Canadian design/build firms- limited track record • Demonstration Program – AAFC/NRCAN - 3 yr - Energy Co-generation from Agricultural/Municipal Wastes (ECoAMu)4 digesters (AB – Beef; SK – Hogs; ON – Beef; QC - Hogs) ManureNet http://res2.agr.gc.ca/initiatives/manurenet/en/hems/ecoamu_main.html
OvercomingBarriers to Adoptionof Anaerobic Digesters • Managing Complexity • A.D. adds yet another new technology to be managed by farmer– Time; Skill-sets • Service agreements • Co-Gen – Power Utility – electricity export • Remote monitoring & process control in real-time – practical technology now available
- 15% feed costs Revenue #2 Electricity Export Anaerobic Digester Cereal Production CO2 Heat Revenue #1 Nutrient Export Nutrient Surplus Organic Fertilizer Electricity Integrated Livestock Farming System Closed Loop Single Farm Energy Centre Nutrient inputs <20% Off-Farm Food-Grade Wastes Nutrient Recycling Co-gen Surplus Co-Located Industries Bio-ethanol plant Greenhouses (Veg., Flowers) Fish Farm Non-Ag Uses Home gardens Turf/golf Parks Local Farm Revenue #3 Optional
CO2 Resource Centre Electricity Heat Clean Water Local MunicipalOrganics Rendering, Deadstock A Centralized Co-operative Rural Energy System Potential Components DewateredDigestate Organic Fertilizers LiquidDigestate water Co-gen Food GradeOrganics Co-Located Industries Greenhouses (Veg., Flowers) Fish Farm Slaughterhouse Bio-ethanol plant Wet Distillers Grain - 15% savings
Challenges Facing Confined Livestock Operations • Increasing price volatility(The China factor) • Less reliable supplies(Declining fossil reserves) • Increasing N fertilizer costs Energy Environment / Health Economics • Increasing regulations – nutrients, pathogens • Municipal waste issues (biosolids) • Rendering / deadstock – limited uses/value • GHG emission reductions – Kyoto protocol • Increasing livestock intensities – odour • Continuing vulnerability of farm incomes • Increasing costs of compliance
Re-DefiningConfined Livestock Farming • Future livestock farming will be structured around bio-energy energy independence using co-gen technologies. • Facilitate conservation and recycling of resources(nutrients, carbon = $$$) • Create greater diversification of income income stabilization (independent from commodity prices!)- Green Electricity- Processed manure solids- Emission Trading Credits- Co-located integrated industries- Tipping fees for food-quality wastes (energy boost)
Re-Defining Confined Livestock Farming • Substantially reduce existing environmental issues– reduced odours, pathogens greater societal support– greater flexibility for applying/selling processed manure • Strengthen rural economy utilizing more local inputs (employment, resource inputs – biomass crops)- Municipality can be a partner (wastes, buy energy)- Farm co-ops take increased control of rural businesses Produce value-added products on-farm- Reduced transportation costs for manufacturing (bio-based)
Farm Bio-Energy CentresAs Integrators & Facilitators Electricity Manure solids Emission credits Tipping fees GHG reductions Deadstock Income Stabilization Environmental Solutions Odours Pathogens Nutrient export & Recycling Reduce herbicide use Independent Of Livestock prices Heat Electricity Clean water CO2 Farm Bio-Energy Energy Independence Rural Revitalization Municipal Organic wastes Co-located industries Local biomass inputs
Considering a Digester? • First Steps(courtesy of Penn State Univ. Extension) • Do your homework — read background info on biogas • Seek preliminary technical assistance • Talk to digester owners • Talk to your electric power company – safety/connects • Investigate potential financial incentives such as tax credits and loans • Talk to digester system designers and installers Selecting a Digester - ManureNethttp://res2.agr.ca/initiatives/manurenet/en/man_digesters.html#Selecting
Micro CHP(Combined Heating and Power)Distributed Power Generation Electricity + Heat generated at each residence Small engine + generator replace furnace & water heater 85 % efficiency Grid
Micro CHP(Combined Heating and Power)Distributed Power Generation
Micro CHP(Combined Heating and Power)Advantages • More efficient use of resources (15% vs 60% loss) (39 vs 85 % efficiency) • Micro CHP units run on natural gas or biogas • Excess electricity exported to grid (10 kw units - $$) • Blackout & Terrorist proof (totally distributed generation) • Significant GHG reductions • Almost eliminate line losses (electricity used on-site) • In Ontario – 2 million homes would produce 10,000 Mw – equivalent to several nuclear power plants • No environmental assessments required – minor impacts • Several thousand units being tested in Europe & Japan; USA senate holding hearings on technology potential
Resource Information on http://res2.agr.gc.ca/initiatives/manurenet/manurenet_en.html • 6,000 external web links • Several hundred digital technical/research reports • Manure Treatment • Digester Compendium • Nutrient Recovery • Ammonia Emissions • Nutrient Management • Environmental Issues • GHG Emissions • Odour Management • Land Application • Storage & Handling • Housing / Feedlots • Feeding Strategies • Codes, Acts, Regulations • Health & Safety • Links • Digital Library • Expertise • Environmental Archive (150 digital reports)