The Quest for Energy Independence City of Fort Worth Village Creek Water Reclamation Facility Biosolids and Odor and Corrosion Conference and Expo July 31 2013 San Marcos, Texas Sebastian Buster Fichera, REM
Sustainability: Perpetual Motion in Nature The use and reuse of matter Taking what nature provides, changing it to meet our needs, then putting it back to be used again.
Service to over 900,000 customers in 23 communities Rated capacity - 166 MGD Average daily flow - 110.7 MGD Average annual biosolids produced - 30,641 dry tons Reuse Water Biosolids Energy
Potential Energy from Biosolids 14-1.2 MG Anaerobic Digesters Average Gas Production 600-800 scfm at 38% VSS destruction Potential Gas Production at 75% VSS destruction 1,170-1,900 scfm
Keep it mixed up Pressure wave mixing Replaced lance gas bubblers 7 foot diameter disk Keeping Solids in suspension Average 28% grit volume 18 inch displacement
8% methane gas Increase due to cleaning and linear mixers 51% methane gas Increase Co-Digestion Start-up
2 5.2 MW Turbine Generators Installed 2000 Provides 45% electrical demand $0.062/kWh Gas Consumption 1700-1900 scfm
Transfer of Energy Nutrients Land Application Irrigation Bacteria Plants Heat Exhaust Animals & Humans Electricity Biosolids Water Methane Waste Waste Treatment
Pre-Turbines Post Turbines 45% Demand 22% Demand
The Village Creek Perpetual Motion Machine Nutrients Land Application Irrigation Bacteria Plants Heat Exhaust Animals & Humans Electricity Steam Biosolids Water Methane Air Waste Waste Treatment
Heat Recovery Steam Generator Recovers 950 o F waste heat from turbine Produces steam at 235 psi Duct burner gas consumption 650 800 scfm 1,300 o F after Duct burner 1750 1900 scfm Gas Gap Total gas demand 2,350 2,700 scfm
Steam Turbines to complete the Cycle 2 Steam drive turbines 2 31,000 scfm blowers Replace 2-1000 h.p. electric blowers at 1.8MW/day
Average Gas Production 600-800 scfm at 38% VSS destruction Potential Gas Production at 75% VSS destruction 1,170-1,900 scfm Leonard Ripley, PhD, P.E. Freese and Nichols 1 MG co-digestion: CH 4 yield = 3,940 SCF/hr Energy yield = 3.8 MM BTU/hr Leonard Ripley, PhD, P.E. Freese and Nichols Purchase more Landfill Gas Solids pretreatment Improve Dig. Eff. Co-digestion
Profile developed to assess waste for: Strength (COD/gas production potential) Loading on the digesters Pollutants that threaten digester performance or sludge quality (i.e. heavy metals, sanitizers, sulfates) Compatibility with other waste streams Solids content: pumpable (at varying temperatures), not diluting digester; limited storage Non-volatile fraction (cost to treat/dispose of residuals)
Accountability, key contact info Contract period Fees Indemnification/liability Sufficient waste to meet gas production needs (and to meet our obligation under our ESPC) Delivery mechanisms and time frames (customers arrange for delivery at their expense and at prescribed schedule)
Build off existing Pretreatment Wastehauler fee structure approved by City Council Continuing gathering data to refine Consideration what the market will bear (significant costs to potential customers associated with transportation) Exempt fees when gas-production potential offsets costs for handling and provides substantial benefit
8% methane gas Increase due to cleaning 51% methane gas Increase Co-Digestion Start-up
81% methane gas Increase Co-Digestion March 2013
94% methane gas Increase Co-Digestion June 2013
4,000.00 3,500.00 Biosolids Production June 2011 - June 2013 Cleanout of Ponds 3,000.00 2,500.00 Dry Tons 2,000.00 1,500.00 1,000.00 500.00 Digester s 9, 10,11,12, 13,14 clean out, linear mixer installation and evaluation 0.00
Pre-Turbines Post Turbines $0.062 kwh $0.041 kwh HRSG 45% Demand 61% Demand
Conclusions Biosolids = Energy Management of biosolids is essential for maximum benefit. Processes required to enhance biosolids breakdown on the front end. Plans to expand from 6 Co-digestion digesters to 14. Goal is to be putting power on the grid by the end of 2014. Energy is all around us.you have to be creative to find it and use it