! Overview of Waste-to-Energy! Waste Sources and Quantities! Waste-to-Energy Drivers and Benefits! West Lafayette Case Study. !

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2 ! Overview of Waste-to-Energy! Waste Sources and Quantities! Waste-to-Energy Drivers and Benefits! West Lafayette Case Study Project Development Digester Performance Biosolids Production Substrate Experience Roadblocks and Lessons! Questions

3 What is Waste-to-Energy? CO 2 CH 4

4 ! Fats, Oils, and Grease (FOG)! Food Waste (commercial and residential)! Agricultural Waste! Dairy Waste! Food Processing Waste (canneries, breweries, wineries)! Glycerin (biodiesel byproduct)! Thin stillage (ethanol byproduct)

5 Sewage back-ups Sewer overflows Clogs onsite drain fields Costly maintenance Potential health impacts More expensive to treat

6 How Much Grease is Out There?! Some Grease Trap Production Rates*: National Avg. = 13.4 lbs/year/person Sacramento, CA Avg. = 11.2 lbs/year/person Provo, UT Avg. = 26.6 lbs/year/person 6,000 tons/day = 300 MW electricity * Source: Wiltsee, G. Urban Waste Grease Resource Assessment. NREL. November 1998

7 40% not eaten

8 Findings:! Commercial 0.25 lb/day/capita! Residential 0.79 lb/day/capita! 80 90% volatile! Better Digestability than Municipal Sludge UNDIGESTED 20,000 tons/day = 200 MW electricity

9 ! Greenhouse gas emissions - methane and carbon dioxide! 23% of methane emissions (2 nd largest)! Health impacts from gas migration! Lost opportunity

10 ! Economics! Risk Reduction! Greater energy self-sufficiency!! Uses excess digester capacity! Provides environmentally sound disposal option for haulers! Reduces GHG emissions and carbon footprint! Opportunity for Waste Diversion! Potential biosolids reduction (FOG)

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12 Digester Problems! Two 60 diam Failing covers Inadequate mixing Poor heating! Digester capacity issues Non-digester issue: Grease in sewer system

13 ! Replaced floating cover with fixed cover - Gained 15% capacity and reliability

14 New Externally Pumped Digester Mixing System

15 Upgraded heating system new water heater and HEX Previous

16 7.5% 28%

17 This plant needs more saturated fat!! Existing City grease trap ordinance problems with grease in collection system! Grease quantity not an issue FOG no stranger to Indiana cuisine Estimated 3,000 gal/day available Hauled 60 miles to Indianapolis

18 FOG Receiving Station Designed FOG receiving station reusing existing Grit Tank 20,000 gal Grit Tank Truck Scale

19 Cogeneration - Capstone Microturbines Two 65-kW units installed Space and Gas Conditioning capacity for 4 total 95% uptime since startup Average 94 kw total output, max of 130 kw

20 ! Primary Food Waste Source: Purdue University Former composting feedstock! Separation Facility: none required!! Ongoing at WWTP since August 2009

21 Step 1:! Clear plate scrapings into dish line trough! ONLY food waste is washed into the trough! All mixed waste is disposed of in standard waste bins

22 Step 2:! Food waste and water flow down trough into the in-line pulper! Pulper grinds and screens to < 3/8 particles In-Line Pulper Trough

23 Step 3:! Food waste is processed through a classifier! Dewaters and thickens the food waste pulp! ~20% solids

24 Step 4:! Food waste pulp is placed in plastic bags! or directly into 33 gallon totes

25 Step 5:! Totes are placed in a truck for transport to City of West Lafayette s WWTP

26 Step 6:! Totes are placed in a tote lifter! Food waste transferred into Receiving Tank

27 Hopper Tote Lifter Grinder Discharge Chute

28 WEST LAFAYETTE WWTP - ANNUAL BIOSOLIDS DISPOSED ()#'' 700 WEIGHT IN DRY TONS *+,-./-0.' '*50+4,' 614./056/+14' $%&'!"#! &"&' (FOG/FW) 2011 (FOG/FW) 2012 (FOG/FW + misc.)

29 (WEFTEC 2010 Marquette University) High COD wastes: 80, ,000 mg/l!

30 Exotic feedstocks accepted: Thin Stillage Wheat Starch Biodiesel Washdown Corn Sugar Washdown Yellow Grease (cooking oil)

31 Pilot Data! Ethanol byproduct! Two 5,800 gallon loads per week! COD = 150,000 mg/l! ph = 5.0! Temperature = 140-deg F Results! Immediate gas production 36 cf/gal stillage PRVs on both digesters popped Waste gas burner flame doubled in height! Noticable struvite in lagoon supernatant! Acid formers got ahead of methane formers! Used up considerable alkalinity

32 Exotic feedstocks considered:! Tomato paste waste! Ice cream waste! Off spec salad dressing! Soy Bean Oil residue from pharmaceutical manufacturing! Large quantities of food waste! Fish processing waste! Biodiesel byproducts

33 1. Material Quality! Almost all substrates have some level of contamination! How much can be accommodated by process equipment?! Debris screening/grinding REQUIRED How does this debris get into grease traps?

34 ! Result of minimal / ineffective screening FOG /FW Metering Pump (progressing cavity) after 2 years operation 01/10'./7/10'

35 2. Blending Waste Streams! FOG/FW do not like to blend form a mat! Effective mixing required 01/708'319-':5;:'<'15/' 7+0';+=+4,'<'+4'

36 3. Digester Capacity and Waste Strength! Too much of a good thing is bad for you (and your digestion)! Typically limit COD from substrates to 30-40% of WW solids! Need effective digester mixing and heating! Need adequately sized gas conveyance system (including flare)! METER HIGH-STRENGTH FEEDSTOCKS IN SLOWLY

37 Energy Independent by 2030! Expanded food waste receiving:! Meal preparation waste! Festivals! Pilot at High Schools **Indiana Governor s Award for Environmental Excellence**

38 Gas utilization options:! Install 1 or 2 more MTs! Conversion to NG for distribution! CNG for vehicle fueling

39 Suitable Substrates: What to Remember! Make it a community effort! Avoid contaminated source streams, or plan accordingly! Balance the C:N to keep digesters happy! Start slowly! Get the word out! Use that extra gas!

40 Questions?