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Feasibility Study on Implementing Dry Fermentation Tech - Spencer


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Feasibility Study on Implementing Dry Fermentation Tech - Spencer

  2. 2. PRESENTED TO 10 th ANNUAL ORGANIC RECYCLING SUMMIT: LOCAL ENERGY TAKES ROOT APRIL 6, 2010 Bob Spencer and Bill Page, Sr. Mass Natural Westminster, MA 978-874-0744
  4. 4. Massachusetts Technology Collaborative <ul><li>Mass Natural feasibility study funding with MTC grant of $40,000, plus $5,000 match </li></ul><ul><li>MTC now Mass Clean Energy (MCE) </li></ul><ul><li>Other food waste anaerobic digestion feasibility studies sponsored by MCE at Southbridge and the six dairy farms project </li></ul>
  5. 5. MASS NATURAL PROJECT TEAM <ul><li>Steve Brunner, P.E., The Brundle Group: anaerobic digestion technology and biogas generation assessment </li></ul><ul><li>Richard Gross, P.E.: electrical interconnect assessment </li></ul><ul><li>Katherine Gegas: Renewable energy credits </li></ul><ul><li>Bruce Fulford: Regulatory assessment </li></ul><ul><li>Bob Spencer: Project management, waste stream survey, and tour of AD facilities in Germany </li></ul><ul><li>Bill Page: Integration with existing operations at Mass Natural </li></ul>
  7. 7. MASS NATURAL’S OPERATION <ul><li>Composting pads and a detention basin for runoff control </li></ul><ul><li>Composting is accomplished by static pile and turned windrows </li></ul><ul><li>Mass Natural recently purchased two in-vessel composting systems that have expanded the range of materials composted </li></ul><ul><li>MN also has a vermicomposting operation to produce vermicompost, as well as red wiggler worms which are offered for sale through the MDEP web site </li></ul>
  8. 8. MATERIALS COMPOSTED SINCE 1987: 23 YEARS OF OPERATION <ul><li>Paper mill sludge, or short paper fiber </li></ul><ul><li>Chicken and horse manure </li></ul><ul><li>Industrial food waste from processors of cranberries, juices, soy, fish, bakeries, FOG </li></ul><ul><li>Yard waste </li></ul><ul><li>Animal mortalities from former chicken egg farm at Mass Natural and as emergency disposal site for MDEP </li></ul><ul><li>Numerous TRIALS with commercial food waste from restaurants and supermarkets (ALWAYS too much inorganic contaminants!!!) </li></ul>
  9. 9. EXISTING PERMITS AT MASS NATURAL <ul><li>Solid Waste Facility Site Assignment from the Town of Westminster Board of Health </li></ul><ul><li>Solid waste composting permits from the Massachusetts Department of Environmental Protection </li></ul><ul><li>Agricultural composting registration from the Massachusetts Department of Agricultural Resources. </li></ul>
  10. 10. MASS NATURAL COMPOST PRODUCTS <ul><li>“ Top Shelf” organic loam, a blend of compost, sand, loam is distributed by a number of garden centers </li></ul><ul><li>Compost is distributed by a number of garden centers </li></ul><ul><li>Vermicompost and red worms for MDEP and garden centers </li></ul><ul><li>Products have been used by the landscaping industry for new lawns, organic lawn care, and athletic fields </li></ul><ul><li>Wetland replication projects </li></ul><ul><li>Landfill cap vegetative cover </li></ul>
  11. 11. HIGH PROFILE COMPOST PROJECTS USING MASS NATURAL PRODUCTS <ul><li>U.S. Army Corps of Engineers wetland reclamation </li></ul><ul><li>New England Patriots Foxboro Stadium playing field reconstruction </li></ul><ul><li>MIT’s Steinbrenner Stadium in-field soil </li></ul><ul><li>Boston Convention & Exposition Center tree plantings </li></ul><ul><li>Clay tennis court soil mix at a private resort on Martha’s Vineyard </li></ul><ul><li>Bank stabilization project for the Mass DEP in Worcester, MA </li></ul><ul><li>Asian Longhorn Beetle control project in Worcester County: loam for tree removal area </li></ul>
  12. 12. SITE ADVANTAGES <ul><li>Existing permits to compost organics; </li></ul><ul><li>Under-utilized, existing buildings within permitted area </li></ul><ul><li>Local electrical distribution line is capable of receiving considerable current from an on-site engine generator; </li></ul><ul><li>Existing equipment (front-end loaders, rotary drum aerobic compost vessel, agitated bay compost system, deck screens, trucks, etc.) and personnel to handle large volumes of organic material; </li></ul><ul><li>Many years of experience with, and understanding of, the local organics market; </li></ul><ul><li>Compost the dry fraction of the digested effluent to add value to its current product; </li></ul>
  13. 13. EXISTING STRUCTURES <ul><li>6 former chicken houses with concrete pads 65 feet wide by 450 feet long, which may be suitable as a floor for some portion of a new AD facility </li></ul><ul><li>A 9,000 sf former egg processing/packaging/storage facility </li></ul><ul><li>Electrical building with 3-phase power </li></ul><ul><li>Existing padmount distribution transformer that is rated 1,000 kVA, sufficient to export the entire 848 kW output from the proposed anaerobic digester </li></ul><ul><li>Water supply wells </li></ul><ul><li>Office </li></ul>
  14. 14. WET VS DRY TECHNOLOGY OR LOW SOLIDS VS HIGH SOLIDS <ul><li>Project started by looking at both wet and dry fermentation systems </li></ul><ul><li>Decision to not pursue wet fermentation due to the fact that there is no sewer connection available at Mass Natural to handle the significant amount of liquid wastewater that would be generated by a wet fermentation system </li></ul><ul><li>Although the liquid wastewater can potentially be land applied, that scenario would have required construction of very large holding tanks, and then contracting for land application, something Mass Natural is not prepared to do at this point in time. </li></ul>
  15. 15. FEEDSTOCKS FOR HIGH SOLIDS ANAEROBIC DIGESTION <ul><li>Approximately 52 tons/day </li></ul><ul><li>Solids Content 62% </li></ul><ul><li>Volatile Solids 88% of Total Solids </li></ul><ul><li>Ammonia/Ammonium Concentration: 3,777Mg/l </li></ul><ul><li>Biogas Generation: 480 m3/hour </li></ul><ul><li>Methane Content 62% </li></ul><ul><li>Electrical Output Potential 1,109kW </li></ul><ul><li>Based on engine-genset electrical efficiency of 36.3% </li></ul>
  17. 17. Electricity Generation <ul><li>At full output, the Jenbacher JS3 316 engine genset has a heat rate of approximately 9,400 Btu/kWh, which translates to an electrical efficiency of 36.3%. </li></ul><ul><li>Given typical operations and maintenance schedules, one can expect an engine genset to operate at full capacity a maximum of 90% of the hours in a year </li></ul><ul><li>A dry digestion system will typically use about 7.5% of the rated electrical output to run the pumps and controls of the plant </li></ul><ul><li>Mass Natural can expect to export a maximum of 6,128,496 kWh/yr. </li></ul>
  18. 18. Thermal Energy <ul><li>Mass Natural can benefit from the thermal energy released from the waste heat from the engine </li></ul><ul><li>The combined heat that can be captured from the engine jacket is about 1.95 MMBtu/hr </li></ul><ul><li>The amount of heat that can be captured from the exhaust stack is about 1.9 MMBtu/hr </li></ul><ul><li>A potential use of the heat is to dry incoming feedstocks </li></ul><ul><li>A rotary drum dryer that would be appropriate at Mass Natural would have a thermal efficacy of about 60% </li></ul><ul><li>For each 4 MMBtu/hr of heat available, a dryer can evaporate approximately 2,500 pounds of water or 300 gallons </li></ul><ul><li>Therefore, in a typical 8-hour shift, MNF could dry 5 tons of material that has a solids content of 35% into 4 tons of material that has a solids content of 45% </li></ul><ul><li>Mass Natural could utilize the 3.85 MMBtu/hr available from the waste heat of the engine </li></ul><ul><li>Another option would be to uses the thermal heat for a greenhouse </li></ul>
  19. 19. HIGH SOLIDS BATCH PROCESSING <ul><li>In a batch process, the digester is completely filled with organic matter and closed with a gas- and liquid-tight seal </li></ul><ul><li>The digester remains closed until the end of the desired retention time, typically 14 to 28 days </li></ul><ul><li>It is then emptied and filled with new material, often a mixture of partially digested material that was just removed and fresh, undigested material </li></ul><ul><li>The partially digested material acts a seed material to re-start the digestion process. </li></ul>
  22. 22. ADVANTAGES OF HIGH SOLIDS AD TECHNOLOGY <ul><li>Because dry material is stackable, the digester can be loaded with a front-end loader, which is already at a compost facility </li></ul><ul><li>When the material is finished digesting, it still has a relatively high solids content. Therefore, the effluent can be composted without having to remove much liquid from it </li></ul><ul><li>Pumping liquid percolate is much easier than pumping slurries, which is the case in most commercial digestion systems. Pumping slurry requires significant horsepower, and the pipes are prone to clogging </li></ul><ul><li>To reduce the impact of reduced biogas production that occurs when the digester is re-filled, multiple digester “cells” can be employed so that several are operating at capacity at any one time </li></ul><ul><li>If one digester cell has an upset condition, the percolate from it is diluted by the percolate from the other cells, making it easier to re-start a “stuck” cell. In an extreme case, the percolate can be completely isolated and removed from circulation </li></ul>
  23. 23. Dry-Batch Digester Installations in Europe
  24. 24. BEKON AND BIOFERM <ul><li>Mass Natural solicited proposals from two German companies, Bekon and Bioferm, that appear to be market leaders </li></ul><ul><li>Each has more than a dozen operating digesters in Europe and is constructing more each month </li></ul><ul><li>Both technologies share a similar process </li></ul>
  25. 25. SIMILAR PROCESS <ul><li>Digestible, organic matter is loaded into a long, narrow gas-tight building </li></ul><ul><li>Once the building is sealed, it is saturated with percolate that contains anaerobic micro-organisms from an active digester </li></ul><ul><li>Percolate is periodically drained and re-sprayed into the digester over a period of approximately 28 days </li></ul><ul><li>Biogas is collected and a combusted in an engine-genset to produce electricity </li></ul><ul><li>Waste heat from the engine is used to maintain an ideal temperature within the digesters </li></ul><ul><li>After the prescribed retention time, the digester is opened, the organic matter is removed, and some of it (a third to half of it) is mixed with fresh organic material and loaded back inside the digester </li></ul><ul><li>The digested material is actively composted. </li></ul>
  30. 30. SUMMARY OF FEASIBILITY STUDY <ul><li>High solids anaerobic process was best suited for the site. </li></ul><ul><li>Mass Natural could digest approximately 52 ton per day of mixed organic matter </li></ul><ul><li>Sufficient biogas to power an 848-kW engine genset that would export over 6.1 MWh a year of renewable electricity </li></ul><ul><li>The system would cost $5.5M to $8.4M </li></ul><ul><li>Annual operating budget of about $277,000 </li></ul><ul><li>Ancillary benefits would include over 3.8 MMBtu/hr of thermal energy for on-site use </li></ul><ul><li>Over 3,250 greenhouse gas emissions credits for sale. </li></ul>
  31. 31. OPERATING COSTS <ul><li>Operating costs for the anaerobic digester system were estimated by the Brendle report to be approx-imately $130,000 per year assuming 1.5 full-time equivalent employees </li></ul><ul><li>Operating costs for the CHP operation are estimated at $137,000 per year </li></ul><ul><li>Total operating cost of $277,000 per year </li></ul>
  32. 32. MASS NATURAL PROJECT REVENUE AND FINANCING FOR $8.4 MILLION FACILITY <ul><li>Project revenue is estimated at approximately $1.9 million in the first year of full operation. That revenue is based on an average tipping fee of $45/ton of feedstock, and receipt of $0.10/kwh of electricity generated. </li></ul><ul><li>Assumptions for project financing were based on 35.5% of total costs financed with solid waste bonds, 23% by investment tax credit, and the balance by equity investment. With this combination of revenue and financing the estimated return on investment, EBITDA (earnings before interest, taxes, depreciation and amortization), divided by pre-debt capital costs, is 13.4% </li></ul><ul><li>This yields a payback period of 7.5 years </li></ul>
  33. 33. CONCLUSIONS <ul><ul><ul><li>• Based on laboratory testing of many of these food wastes, it was determined that 20,000 tons per year of food wastes would generate sufficient quantities of biogas to power a 848 kW generator. </li></ul></ul></ul><ul><ul><ul><li>• Two technology vendors with numerous, successfully operating high solids anaerobic digestion technologies currently operating in Germany have technology that is technically feasible for implementation at Mass Natural. </li></ul></ul></ul><ul><ul><ul><li>• Sufficient types and quantities of industrial food waste are available within economical hauling distances of Mass Natural’s Westminster, Massachusetts composting facility to supply a 20,000 ton per year high solids anaerobic digestion facility. </li></ul></ul></ul><ul><ul><ul><li>• The electrical interconnection from a generator powered by an anaerobic digester is feasible and economical at Mass Natural. </li></ul></ul></ul>
  34. 34. CONCLUSIONS <ul><ul><ul><li>• The Mass Natural site has sufficient space to locate an anaerobic digestion facility </li></ul></ul></ul><ul><ul><ul><li>• The current composting operation at Mass Natural would be a complimentary operation for an anaerobic digestion facility </li></ul></ul></ul><ul><ul><ul><li>• The regulatory approval process for an anaerobic digestion facility at Mass Natural was determined to be feasible. </li></ul></ul></ul><ul><ul><ul><li>• The capital costs for an anaerobic digestion facility at Mass Natural was determined to be between $5.5 and $8.4 million. For a 20,000 ton per year facility this was determined by Mass Natural to be a marginal investment. </li></ul></ul></ul><ul><ul><ul><li>• Mass Natural would like to conduct further evaluation to identify less costly high solids dry fermentation technologies. </li></ul></ul></ul>