manure – a multi-purpose resource : ”things are changing in the barnyard!”
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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. - PowerPoint PPT PresentationTRANSCRIPT
Manure – A Multi-Purpose Resource:”Things are Changing in the Barnyard!”
Bruce T. Bowman
Expert Committee on Manure ManagementCanadian 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
Three priority issues to manage:
Nutrients Odours Pathogens
............................. but also …….
Manure ManagementPriority Issues
Context: Presentation will be more applicable for larger confined livestock operations than for grazing-based systems.
Water volumes Carbon = Energy $$$
Two major loss pathways:
As volatile ammonia (NH3)
As nitrous oxide (N2O) (greatest impact of GHGs – 310x effect of CO2)
Gaseous losses can occur at any stage of handling with continued exposure to air.
Conserving Nutrients:Gaseous Nitrogen losses from Manure
pH 9.4 [NH3] / [NH4+] = 0.50 (50%) @(20°C)pH 7.5 [NH3] / [NH4+] = 0.018 (1.8%)pH 7.0 [NH3] / [NH4+] = 0.0056 (0.56%)
Keep pH near 7 (neutrality) to minimize NH3 losses
Conserving Nutrients:Ammonia losses from Manure
Ammonium (NH4+) - non-volatile; Ammonia (NH3) - volatile
Ammonia losses are also rapid from bare floors; Remove manure when fresh to closed storage to minimize NH3 losses.
Why should we minimize these losses?
Increasing replacement costs for commercial N = $$$- 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:Ammonia losses from Manure
Conserving Nutrients:Nitrous Oxide Production
Oxidation
Reduction**
Nitrification & denitrification are biological processes 30° - 40°C
Nitrification
Denitrification
ammonium nitrate
nitrate nitrogen gas
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)
Conserving Nutrients:Reducing Nitrous Oxide Emissions
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
HumanConsumptionCereal Production
LARGE-SCALE NUTRIENT FLOWSRecycling Nutrients & Organic Matter
AnnualMineral
FertilizerAdditions
Nutrients & O.M. NOT recycled
Regional nutrient excesses
Local Farm
Manure
Nutrients O.M.
Wastes
Landfills
Nutrient inputs
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).
Reasons to Recycle Livestock Nutrients
Balancing Nutrient INPUTS & OUTPUTS at 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)
Whole Farm Nutrient Balances(Budgets)
Three Options (singly or in combination)
1. Reduce nutrient inputs to balance nutrient exports from the land base (e.g. improved feeding strategies – nutrient use efficiency e.g. phytase).
2. Increase land base for applying manure nutrients (buy, rent more land or contract for exporting excess manure; Exporting liquid manure nutrients < 15 km radius (economics).
3. Export surplus nutrients from the farm in the form of value-added products (new revenue - organic fertilizers/amendments).
Managing On-Farm Nutrient Surpluses
Criteria for exporting manure nutrients: Odour-free Pathogen-free Dewatered (dried) for transportation
Manure processing can address these issues.
Requirements for Exporting Surplus Livestock Nutrients
The need to export surplus nutrients will increase with further intensification of livestock operations.
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 with increased flexibility for managing surplus nutrients, while solving other environmental problems.
Societal
Reduce siting / zoning problemsRegain public support
Opportunity for new rural partnerships
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
Yield / Productivity
Environmental Protection
S
oci
etal
Co
nce
rns
Balancing Issues in a Sustainable Farming Operation
1. Yield/Productivity (economics)
2. Environmental Protection
Both are science-based
3. Societal Concerns
Perception-based, emotional
Can over-ride other 2 factors.
Opposition difficult to reverse once initiated
Pre-1965
Since 1970s 2-D
Since 1990s 3-D
Anaerobic DigestionProcesses
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
A Few 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)
Anaerobic Digestion
…….. More Facts
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
Anaerobic Digestion – best solution for deadstock and for animal rendering – 2 valuable end products
Renewable energy recovery (heat, electricity) Organic fertilizer/amendment end product
Managing Dead StockA Waste + Nutrient Issue
Pre-treatment = shredder + Pressure/Temperature - treated waste virtually all digestible
- possible elimination of BSE prions
Conserves N, P & some C for recycling back to land Minimizes odour problems; eliminates pathogens
Types of Anaerobic Digesters
Courtesy of: US EPA AgStar Handbook
Components of a Complete Mix Mesophillic Digester
Courtesy: Rentec Renewable Technologies
Buffer tank - Premix
Hydraulic reactor
Combined Gas + Effluent Storage
Co-Gen Set
Remove foreign materials
Grid
High Tech
Manure Processing Anaerobic Digestion
Low Tech
1. Initial Investment / Payback Issues
2. Regulatory Issues
3. Reliability, Trust & Expertise
4. Managing Complexity
Barriers to Adoption of Anaerobic Digesters
1. 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
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 1. 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)
2. 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
Overcoming Barriers to Adoption
of Anaerobic Digesters
3. 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)
OvercomingBarriers to Adoption
of Anaerobic Digesters
ManureNet
http://res2.agr.gc.ca/initiatives/manurenet/en/hems/ecoamu_main.html
4. 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
OvercomingBarriers to Adoption
of Anaerobic Digesters
Revenue #2Electricity
Export
Revenue #1Nutrient Export
Integrated Livestock Farming System
Closed Loop Single Farm Energy Centre
Local Farm
Organic Fertilizer
Non-Ag UsesHome gardens
Turf/golfParks
Nutrient
SurplusCo-Located Industries
Bio-ethanol plantGreenhouses
(Veg., Flowers)Fish Farm
Cereal Production
- 15% feed costs
Revenue #3Optional
Nutrient
Recycling
Anaerobic
Digester
<20% Off-Farm Food-Grade Wastes
Nutrient inputs
Co-gen
SurplusElectricity
Heat
CO2
Co-Located Industries
Greenhouses(Veg., Flowers)
Fish FarmSlaughterhouse
Bio-ethanol plant
A Centralized Co-operative Rural Energy System
Potential Components
LiquidDigestate
Resource Centre
Electricity
Clean Water
Heat CO2
DewateredDigestate
Food GradeOrganics
Local MunicipalOrganics
Rendering, Deadstock
Organic Fertilizers
water
Co-gen
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
Continuing vulnerability of farm incomes Increasing costs of compliance
Increasing regulations – nutrients, pathogens Municipal waste issues (biosolids) Rendering / deadstock – limited uses/value GHG emission reductions – Kyoto protocol Increasing livestock intensities – odour
Energy
Environment
/ Health
Economics
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)
Re-Defining Confined Livestock Farming
ElectricityManure solids
Emission credits
Tipping fees
Heat Electricity
Clean waterCO2
Municipal Organic wastes
Co-located industriesLocal biomass inputs
OdoursPathogens
Nutrient export & Recycling
Reduce herbicide
use
GHG reductionsDeadstock
Farm Bio-Energy CentresAs Integrators & Facilitators
EnvironmentalSolutions
IncomeStabilization
Rural Revitalization
Farm Bio-Energy
EnergyIndependence
IndependentOf
Livestockprices
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
Considering a Digester?
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 residenceSmall engine + generator replace furnace & water heater
Grid
85 % efficiency
Micro CHP (Combined Heating and Power)Distributed Power Generation
Centralized Gas-Fired Plant Micro CHP
INPUT 100 100
Waste Energy 57 <15
Line Losses 4 - 7 0
Electricity 39 20
Useful Heat Energy 0 65
Net Useful Energy 36-39 85+
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
Micro CHP (Combined Heating and Power)
Advantages
Resource Information on
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6,000 external web links Several hundred digital technical/research reports
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