Optimum usage and economic feasibility of animal manure-based biomass in combustion systems Nicholas T. Carlin [email_addr...
Overview <ul><li>Biomass supply and properties </li></ul><ul><li>Option 1: Large scale combustion of biomass </li></ul><ul...
Introduction – CAFOs <ul><li>About  10 million beef cattle  on feed in USA </li></ul><ul><li>5 dry kg (11 lb) manure per a...
Dairy Cows <ul><li>About  9.1 million dairy cows  in USA </li></ul><ul><li>6.4 dry kg (14 lb) manure per animal per day  (...
Fuel Analyses
Bulk Density of Manure Biomass Data from Chen, 1983,  Ag. Wastes   6 Curve fit to Chen’s data
Modeling Particle Distribution and Specific Heat Porosity: Specific heat of bone dry biomass solids, adapted from Bohnhoff...
Thermal Energy Conversion of Manure OPTION 1 :  Large-scale combustion OPTION 2 :  Small-scale, on-the-farm combustion Dry...
Option 1 Large Scale Combustion
Transporting Manure Biomass Centralized drying and composting facility <30 km (<20 miles) 80-320 km (50-200 miles) Dairy D...
Biomass Drying Operations boiler Natural Gas or Electric Warm Air Air Steam <ul><li>Capital Costs : </li></ul><ul><li>Drye...
Transporting Biomass <ul><li>Known Parameters: </li></ul><ul><ul><li>Loading and unloading time </li></ul></ul><ul><ul><li...
Other Processing at Power Plant Existing coal injection Biomass stockpile Transport or hauling vehicle Front end loader Me...
General Combustion Model Combustion System <ul><li>Coal and/or manure biomass </li></ul><ul><li>With a moisture percentage...
Co-firing Blending coal with biomass in primary burn region Direct coal and biomass blend and injection if biomass  heat f...
Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Diesel, natural gas, propane fueling costs Labor & Maintenance Co...
Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Operating cost/revenue Annual Cash Flows Capital Costs Operating ...
Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Net Present Value Net Present Worth Net Present Cost OR
Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Annualized cost or revenue Annual Cash Flows
Co-firing with Biomass Steps in Analysis <ul><li>Compiled modeling equations into a spreadsheet computer program (Excel). ...
Base case Inputs for Co-firing <ul><li>Plant base inputs: </li></ul><ul><ul><li>Plant Capacity: 300 MW e  (35% efficiency)...
Base case Inputs for Co-firing <ul><li>Pricing </li></ul><ul><ul><li>Coal : $30/ton (3.77% annual escalation) </li></ul></...
Year One Comparison Total Operating Cost @ Y1 = $1.2 million
Annual Cash Flow for Base Case NPW = -$22.6 million
Base Case Results <ul><li>Total investment for plant equipment, dryers, and trucks = $5.9 million </li></ul><ul><li>NPW = ...
Effect of Coal Prices
Effect of CO 2  Value Co-firing with biomass becomes profitable
Cost components of co-firing vs. transport distance 70 – 80% of drying cost due to natural gas
Cases where natural gas may not be needed May be the case for dairies and feedlots in the Texas Panhandle Region NPW = -$2...
Reburning to reduce NO x <ul><li>Primary Coal Injection </li></ul><ul><li>Along with primary combustion air </li></ul><ul>...
Different base case inputs for Reburning <ul><li>Tangentially fired boiler using low-NO x  burner with closed coupled over...
Effect of NO x  Value
Effect of NO x  Value
Option 2 Small-scale, On-the-farm Combustion
Solids Separator Pump Process  (e.g. space heating, hot water generator, etc.) Flushed Manure Slurry 90-99% moisture Semi ...
Disposal Efficiency Mass of flushed manure leaving the animal housings Mass of wastewater not vaporized in the boiler Mass...
Tracking Results in Spreadsheet
Dryer Design
Effect of Ash Percentage
Additional Fueling
Summary <ul><li>Bottom line: </li></ul><ul><ul><li>Large scale combustion of manure-based biomass can be profitable, but a...
Summary (cont.) <ul><li>Currently , given the high cost of transporting manure and preparing it for combustion in coal bur...
Summary (cont.) <ul><li>As for drying and transporting: </li></ul><ul><ul><li>Rotary dryers were found to consume slightly...
Acknowledgments <ul><li>DOE--Golden, Colorado, Grant #DE-FG36-05GO85003 and </li></ul><ul><li>Texas Commission on Environm...
Questions? [email_address]
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Presentation - Coal and Biomass Combustion

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These are slides from my doctoral defense in March 2009. Supply and properties of biomass are discussed. The proposed co-firing and reburing of coal with biomass is then presented. Finally, a conceptualized model of a waste-based biomass disposal system is presented. If you have any interests or questions of this work or if you would like to see this presentation with animated graphics, please e-mail Nicholas Carlin at ncarlin50@hotmail.com.

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Presentation - Coal and Biomass Combustion

  1. 1. Optimum usage and economic feasibility of animal manure-based biomass in combustion systems Nicholas T. Carlin [email_address] Under the advisement of: Dr. K. Annamalai & Dr. W. Harman Texas A&M University, Dept. of Mechanical Engineering March 9, 2009
  2. 2. Overview <ul><li>Biomass supply and properties </li></ul><ul><li>Option 1: Large scale combustion of biomass </li></ul><ul><ul><li>Co-firing coal with biomass </li></ul></ul><ul><ul><li>Reburning coal with biomass </li></ul></ul><ul><li>Option 2: Small scale combustion of biomass </li></ul><ul><li>Summary </li></ul><ul><li>Acknowledgments </li></ul>
  3. 3. Introduction – CAFOs <ul><li>About 10 million beef cattle on feed in USA </li></ul><ul><li>5 dry kg (11 lb) manure per animal per day (collectable) </li></ul><ul><li>Over 18 million dry metric tons of manure per year </li></ul><ul><li>109 million GJ/yr (103 million MMBtu/yr), if 70% ash </li></ul>Sources: NASS of the USDA ASAE standard D384.2 MAR2005 www.factoryfarm.org
  4. 4. Dairy Cows <ul><li>About 9.1 million dairy cows in USA </li></ul><ul><li>6.4 dry kg (14 lb) manure per animal per day (collectable) </li></ul><ul><li>Over 21.2 million dry metric tons of manure per year </li></ul><ul><li>255 million GJ/yr (242 million MMBtu/yr), if biomass is 40% ash </li></ul>Sources: NASS of the USDA ASAE standard D384.2 MAR2005 www.tnr.com (The New Republic)
  5. 5. Fuel Analyses
  6. 6. Bulk Density of Manure Biomass Data from Chen, 1983, Ag. Wastes 6 Curve fit to Chen’s data
  7. 7. Modeling Particle Distribution and Specific Heat Porosity: Specific heat of bone dry biomass solids, adapted from Bohnhoff et al ., 1987. Specific heat of wet biomass solids
  8. 8. Thermal Energy Conversion of Manure OPTION 1 : Large-scale combustion OPTION 2 : Small-scale, on-the-farm combustion Drying Grinding and other processing Emission and dollar savings (or costs)? Overall economic feasibility? Waste disposal plus co-benefit of usable energy or thermal commodities Design considerations. Gross economic study. Power Plant
  9. 9. Option 1 Large Scale Combustion
  10. 10. Transporting Manure Biomass Centralized drying and composting facility <30 km (<20 miles) 80-320 km (50-200 miles) Dairy Dairy Large feedlot or CAFO Power Plant
  11. 11. Biomass Drying Operations boiler Natural Gas or Electric Warm Air Air Steam <ul><li>Capital Costs : </li></ul><ul><li>Dryer = f (belt area) </li></ul><ul><li>Boilers </li></ul><ul><li>Manure Loaders </li></ul><ul><li>Land Purchases </li></ul><ul><li>O&M Costs : </li></ul><ul><li>Dryer </li></ul><ul><li>Boilers </li></ul><ul><li>Loaders </li></ul><ul><li>Gas and/or electric </li></ul><ul><li>Labor </li></ul>
  12. 12. Transporting Biomass <ul><li>Known Parameters: </li></ul><ul><ul><li>Loading and unloading time </li></ul></ul><ul><ul><li>Average speed of the trucks </li></ul></ul><ul><ul><li>Hauling schedule – hours per day hauling </li></ul></ul><ul><ul><li>Number of days per year hauling </li></ul></ul><ul><ul><li>Volume capacity of each truck </li></ul></ul><ul><li>Must find: </li></ul><ul><ul><li># of trips, # of trucks </li></ul></ul><ul><ul><li>Total driving hours (labor) </li></ul></ul><ul><ul><li>Diesel fuel consumption </li></ul></ul>40 cubic yard trailer ( www.montonetrailers.com )
  13. 13. Other Processing at Power Plant Existing coal injection Biomass stockpile Transport or hauling vehicle Front end loader Metal detector Magnetic separator Scale Screen Feeder Grinder Air intake Exhaust Silo Vent Scale Feeder Pressure blower Biomass reburn fuel Biomass co-fired fuel <ul><li>Lower NO x </li></ul><ul><li>Lower nonrenewable CO 2 </li></ul><ul><li>Better oxidation of Hg </li></ul>Higher Ash Output Overall cost estimates for these operations for reburn and co-fire systems exist in the literature [adapted from the DOE, 2004, Fed. Energy Management Program] Separator
  14. 14. General Combustion Model Combustion System <ul><li>Coal and/or manure biomass </li></ul><ul><li>With a moisture percentage, % M , </li></ul><ul><li>Ash percentage, % A , and </li></ul><ul><li>Temperature, T fuel </li></ul><ul><li>Combustion Air </li></ul><ul><li>At some excess percentage, % EA , of stoichiometric level, </li></ul><ul><li>At some temperature T air , and </li></ul><ul><li>Some relative humidity </li></ul>CV ref Q loss <ul><li>Products of Combustion </li></ul><ul><li>At some temperature, T out </li></ul>Mass balance : Energy balance :
  15. 15. Co-firing Blending coal with biomass in primary burn region Direct coal and biomass blend and injection if biomass heat fraction ≤ 2% Secondary and tertiary air Additional injection system for biomass if biomass heat fraction > 2% Secondary and tertiary air <ul><li>Emissions for MBB blends generally : </li></ul><ul><li>Lower in nonrenewable CO 2 , </li></ul><ul><li>Higher in SO 2 , and </li></ul><ul><li>Higher in fly ash. </li></ul>Higher bottom ash levels CV ref
  16. 16. Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Diesel, natural gas, propane fueling costs Labor & Maintenance Coal savings Avoided CO 2 and NO x emission allowances Annual Cash Flows Capital Costs New plant equipment and retrofit Dryer facility and equipment Transport vehicles
  17. 17. Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Operating cost/revenue Annual Cash Flows Capital Costs Operating cost or revenue New plant equipment and retrofit Dryer facility and equipment Transport vehicles
  18. 18. Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Net Present Value Net Present Worth Net Present Cost OR
  19. 19. Project time (yrs) Cash Flows (Dollars) 30 15 20 25 5 10 Annualized cost or revenue Annual Cash Flows
  20. 20. Co-firing with Biomass Steps in Analysis <ul><li>Compiled modeling equations into a spreadsheet computer program (Excel). </li></ul><ul><li>Generated a base case reference run of the program. </li></ul><ul><li>Conducted a sensitivity analysis of the net present worth of the co-fire system by varying each individual parameter, while holding all other parameters constant. </li></ul>
  21. 21. Base case Inputs for Co-firing <ul><li>Plant base inputs: </li></ul><ul><ul><li>Plant Capacity: 300 MW e (35% efficiency) </li></ul></ul><ul><ul><li>Burning WY sub-bituminous </li></ul></ul><ul><ul><li>FGD is installed, 20% of ash is sold </li></ul></ul><ul><li>Co-firing Biomass </li></ul><ul><ul><li>5% (by mass) low-ash dairy biomass </li></ul></ul><ul><ul><li>Each biomass dryer has a 2 dry metric ton capacity (fueled with natural gas) </li></ul></ul><ul><ul><li>Biomass transported 80 km (50 miles) </li></ul></ul>
  22. 22. Base case Inputs for Co-firing <ul><li>Pricing </li></ul><ul><ul><li>Coal : $30/ton (3.77% annual escalation) </li></ul></ul><ul><ul><li>CO 2 value : $3.50/ton (5.25% escalation) </li></ul></ul><ul><ul><li>SO x value : $880/ton (4% escalation) </li></ul></ul><ul><ul><li>Natural gas : $7.76/MMBtu (5% escalation) </li></ul></ul><ul><ul><li>Electricity : $0.09/kWhe (3.70% escalation) </li></ul></ul><ul><ul><li>Diesel : $3.00/gallon (5% escalation) </li></ul></ul><ul><li>Economics: </li></ul><ul><ul><li>5.3% non-inflated discount rate </li></ul></ul><ul><ul><li>4% inflation  9.5% inflated discount rate </li></ul></ul><ul><ul><li>12.1% capital charge rate </li></ul></ul><ul><ul><li>34% tax rate (MACRS of depreciation) </li></ul></ul>
  23. 23. Year One Comparison Total Operating Cost @ Y1 = $1.2 million
  24. 24. Annual Cash Flow for Base Case NPW = -$22.6 million
  25. 25. Base Case Results <ul><li>Total investment for plant equipment, dryers, and trucks = $5.9 million </li></ul><ul><li>NPW = -$22.6 million </li></ul><ul><ul><li>Annualized cost = $2.30 million per year </li></ul></ul><ul><ul><li>Cost of reducing CO 2 = $35.68/ton CO 2 </li></ul></ul><ul><ul><li>Cost of co-firing = 0.11 ¢/kWh e </li></ul></ul><ul><ul><ul><li>If avg. household consumes 940 kWh e per month, co-firing with manure biomass would increase electric bills by about $1.03 per month. </li></ul></ul></ul>
  26. 26. Effect of Coal Prices
  27. 27. Effect of CO 2 Value Co-firing with biomass becomes profitable
  28. 28. Cost components of co-firing vs. transport distance 70 – 80% of drying cost due to natural gas
  29. 29. Cases where natural gas may not be needed May be the case for dairies and feedlots in the Texas Panhandle Region NPW = -$22.6 million NPW = +$2.1 million Waste heat utilized from power plant
  30. 30. Reburning to reduce NO x <ul><li>Primary Coal Injection </li></ul><ul><li>Along with primary combustion air </li></ul><ul><li>Reburn Fuel Injection </li></ul><ul><li>Usually natural gas or coal, but could be manure biomass , </li></ul><ul><li>10-20% of the plant heat rate </li></ul><ul><li>Rich mixture, ER = 1.05 – 1.2 </li></ul><ul><li>Temperature: 1300-1500 K </li></ul>High NOx emission Lower NO x emission 60 to 90% reduction <ul><li>Over Fire Air </li></ul><ul><li>Completes the combustion process </li></ul><ul><li>Exhaust Gases </li></ul><ul><li>With acceptable NO x emission </li></ul><ul><li>Lower CO 2 emission from nonrenewable sources </li></ul>Higher bottom ash levels CV ref
  31. 31. Different base case inputs for Reburning <ul><li>Tangentially fired boiler using low-NO x burner with closed coupled over fire air </li></ul><ul><ul><li>Primary NO x control can achieve levels of 0.20 lb/MMBtu </li></ul></ul><ul><li>Reburn fuel is pure low-ash dairy biomass </li></ul><ul><ul><li>10% heat contribution to overall heat rate </li></ul></ul><ul><ul><ul><li>(13% by mass) </li></ul></ul></ul><ul><ul><li>Reburning achieves levels of 0.06 lb/MMBtu </li></ul></ul><ul><li>Alternatively, SCR can also achieve levels of 0.06 lb/MMBtu </li></ul><ul><li>NO x value: $2,600/ton NO x (4.5% escalation) </li></ul>
  32. 32. Effect of NO x Value
  33. 33. Effect of NO x Value
  34. 34. Option 2 Small-scale, On-the-farm Combustion
  35. 35. Solids Separator Pump Process (e.g. space heating, hot water generator, etc.) Flushed Manure Slurry 90-99% moisture Semi solids 50-70% moisture Vapor Exhaust Biomass Solids 15-30% moisture Bottom Ash Exhaust Products Wastewater 1-6% solids Condensate for continued flushing Recycled wastewater for flushing or treatment lagoon Saturated Steam Remaining solids %M=?? Condensate for continued flushing Proposed Manure Waste Disposal Combustion System for on-the-farm disposal Combustion Air Air Air
  36. 36. Disposal Efficiency Mass of flushed manure leaving the animal housings Mass of wastewater not vaporized in the boiler Mass of remaining ash
  37. 37. Tracking Results in Spreadsheet
  38. 38. Dryer Design
  39. 39. Effect of Ash Percentage
  40. 40. Additional Fueling
  41. 41. Summary <ul><li>Bottom line: </li></ul><ul><ul><li>Large scale combustion of manure-based biomass can be profitable, but a lot has to happen. </li></ul></ul><ul><ul><ul><li>Manure must be low in ash </li></ul></ul></ul><ul><ul><ul><li>Coal prices must be high </li></ul></ul></ul><ul><ul><ul><li>NO x and CO 2 values must be high and expected to escalate </li></ul></ul></ul><ul><ul><ul><li>Using high-grade fuels to dry the manure should be avoided </li></ul></ul></ul><ul><ul><ul><li>Reburning is theoretically more profitable than co-firing, but there are many feasibility issues and simply not enough possible applications for reburning in the US. </li></ul></ul></ul><ul><ul><li>Small scale combustion is highly dependant on two things </li></ul></ul><ul><ul><ul><li>Avoided manure waste disposal costs </li></ul></ul></ul><ul><ul><ul><li>Earning profit from electricity or thermal commodity (e.g. steam) production </li></ul></ul></ul>
  42. 42. Summary (cont.) <ul><li>Currently , given the high cost of transporting manure and preparing it for combustion in coal burners, as well as the lack of available low-ash manure and the lack of real dollar benefits, small-scale combustion is preferable . </li></ul><ul><li>Future carbon taxes or cap-n-trade programs can greatly improve the possibility of burning manure biomass in coal-fired power plants. </li></ul>
  43. 43. Summary (cont.) <ul><li>As for drying and transporting: </li></ul><ul><ul><li>Rotary dryers were found to consume slightly less heat energy than conveyor belt dryers </li></ul></ul><ul><ul><li>Due to the relationship between manure density and moisture percentage, there seems to be little difference in costs between transporting manure with 20% moisture and manure with 60% moisture. </li></ul></ul><ul><ul><li>Although transporting liquid manure, >90% moisture, is significantly more expensive. </li></ul></ul>
  44. 44. Acknowledgments <ul><li>DOE--Golden, Colorado, Grant #DE-FG36-05GO85003 and </li></ul><ul><li>Texas Commission on Environmental Quality (TCEQ), Grant #582-5-65591 0015 </li></ul>
  45. 45. Questions? [email_address]

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