Wasting Resources Evaluating Heat & Water Recovery Opportunities in Wastewater Systems

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1 Wasting Resources Evaluating Heat & Water Recovery Opportunities in Wastewater Systems Chris Johnston, PEng Kerr Wood Leidal Associates Erik Lindquist, PEng DEC Design Mechanical Consultants 1

2 Outline Sewage Heat Characteristics District Energy Systems Master Planning Feasibility Analysis Developing a Business Case Design & Construction 2

3 How Much Heat Are You Wasting In Your Municipality? Estimated Heat Energy in Wastewater L/PE/d) 70, SF Equivalent Homes 60,000 50,000 40,000 30,000 20,000 Homes Energy Annual Energy (TJ) 10, Metro Van CRD Surrey Burnaby Abbotsford Kelowna 0 3

4 Why Sewer Heat? Energy is wasted constantly But much is recoverable Any sizeable town/city has sewers and treatment plants Only moderate initial capital required Energy savings Grants & rebates GHGs reduced Provides opportunities for further expansion and innovation 4

5 How Does It Work? Heat pump or heat exchanger used to extract heat energy from wastewater Transfers heat to carrier fluid in a District Energy System (DES) DES transports heat to end users, displacing natural gas and reducing electricity use 5

6 Heat Sources in Wastewater Heat energy stored in water (J/m3/ºC) Domestic hot water, industrial wastewater Some energy from groundwater (I&I) ºC C in winter to 20+ºC C in summer Can extract from raw or treated effluent Waste heat is primary source of energy Digested sludge may also provide energy source 6

7 Estimating Heat Supply Heat Energy Transfer Determined As: ΔQ Q = m c ΔT Where ΔQ Q = Heat Energy (J) m = mass (kg), i.e. dry weather flow c = specific heat of water (4,187 J/kg/K) ΔT T = temperature drop (K or ºC) 7

8 Capturing the Heat How it Works 8

9 Basic Concept Low Temperature System DES Return DES Supply 4ºC 13-18ºC 45-65ºC Hot Water Heat Pump Wastewater Get m from wastewater flow (m3/s = 1000 kg/s) c is the same if DES uses water as carrier fluid Effluent Return min. 4ºC ΔT = ºC Effluent Supply 15-20ºC Heat Recovery Facility (Heat Exchanger) 9

10 Four Steps to Wastewater Heat Recovery Projects 1. District Energy Master Plan 2. Feasibility Studies 3. Business Case 4. Design, Build, Operate Master plan establishes goals, develops understanding and identifies key DE opportunities Feasibility studies refine DE concepts, identify individual participants (and defines the stages to maximize benefits) Business case defines terms of future energy utility or service 10

11 Step 1 Master Plan Case Study: Capital Regional District Wastewater Management Strategy Determine where best locations to utilize energy exist currently and in the future Economic analysis based on life-cycle cost of energy production Estimate potential revenue stream to municipality Steer wastewater treatment strategy through resource recovery 11

12 Master Plan Framework Identify Heat Sources WWTP Outfall Pump Stations Trunk Sewers Forcemains Other Waste Heat Identify Opportunities High Density Retrofits & Redevelopment Institutional/ Civic New Developments Evaluate Building Systems Develop Recovery Strategy Raw or Treated Source Secondary Sources? Proximity to Supply DES Concept Water re-use opportunities Evaluate Feasibility Size DES Capital O&M Ownership Pricing Staging GHGs 12

13 Sewer Heat Source Map Sewer Heat Supply GIS Model Mains 450+ mm Heat Energy in Sewers Low Pump Stations High 13

14 Potential DES Customers Sewer Heat Demand GIS Model Energy Density and Boilers Westhills North Douglas UVic Royal Jubilee James Bay/ Downtown 14

15 DES Model For Downtown Area DES Infrastructure GIS Model Demand-Distance Optimization Least-Cost Path Distribution Route WWTP User-Defined Transmission Lines Customers Analysis Boundary 15

16 Energy Cost Analysis Maximizing the Cost Benefit Energy Cost Versus Demand Density Energy Cost ($/GJ) Projects above dashed too costly for commercial venture Projects below dashed line have revenue potential Van. Island Natural Gas Rate Energy Demand Density (GJ/ha/year) 16

17 Go For The Low-Hanging Fruit First! Comparing the Costs Diesel Electricity Add carbon tax for natural gas: $0.50/GJ $0.75/GJ $1.50/GJ Natural Gas Furnace High Efficiency Gas Boiler BC Hydro Electricity Solar PV Building Retrofit Solar Thermal Geoexchange Biogas Conversion Air Source Heat Pump Waste Sewer Heat Sweet Spot (Natural Gas $14/GJ 2008) $100+/GJ { $15 $10 Approximate Life-Cycle Unit Energy Cost $5/GJ 17

18 Step 2 - Feasibility Confirm existing demands and building infrastructure Select type of DES that will be most applicable Evaluate additional renewable and recoverable energy sources Investigate building retrofit options Identify infrastructure phasing Identify non-potable water demand opportunities 18

19 District Energy Systems Maximizing Energy Recovery - Minimizing Cost Ambient Supply Return Typical DES Configuration Access to Single Source One Design Temp Difficult to Scale District Energy Sharing Heating/Cooling Energy Storage Multiple energy source/sink Minimal head pressure Highly Scalable Non-Potable Water Uses Net Metering Option District Heating System Small Pipe Industry Standard Controls Single Heat Pump or Heat Source Heat Exchangers to Provide Heat Where Needed Hybrid District Systems Optimal Distribution & Delivery Match Delivery to Building Need Maximize Distribution Efficiency Non-Potable Water Uses 19

20 Two Pipe Reverse Return Supplementary Source HP/HX HP/HX Primary Source HP/HX HP/HX 20

21 DESS - Warm Cool Pipe Sourc e Sourc e 21

22 District Energy Sharing System 22

23 Hybrid DESS Optimizing Distribution & Delivery 23

24 District Energy Benefits Scalable - Modular - Net Meter Ready > 80% Reduction in Building Heating/Cooling Energy Demand (New Construction) > 40% Reduction in Potable Water Demand >80% Energy Reduction Typical on Retrofit Civic Building >80% GHG Reduction 24

25 Case Study: Delta Municipal Precinct Renewable and recoverable energy sources Building retrofit options Infrastructure phasing District Energy Sharing System concept 25

26 Retrofit Costs Establishing Real Costs - Getting Real Benefits Full Build Out $5-7.5M Phase 1 Build $3-5.5M Incremental $1.2-3M Rec Centre <1M 26

27 Step 3 Business Case Ownership Model Municipal Department or Service Municipal Subsidiary Corporation Public-Private Private Partnership Third-Party Utility 27

28 Financial Strategy Getting Real Benefits Energy must be cost-competitive competitive with conventional energy ($10-15/GJ) 15/GJ) Recovered water must be attractive ($0.40 m 3 ) Reserve Funds / Developer Cost Charges Grants and Ownership Options Payback in Under 10 years 28

29 Implementation Plan Infrastructure Phasing Infrastructure can be constructed in modules Provides thin end of the wedge for integration of other technologies Policy Issues How are heat rights determined? Who get credits for GHG reduction? Are champions in place to support DES? 29

30 Step 4 Design, Build, Operate Whistler Athletes Village District Energy Sharing System (WAVDESS) 2-pipe, closed loop DESS Provides heating and cooling to Athletes Village Wastewater primary heat source Backup natural gas boiler 70% reduction in GHGs compared to business-as as-usual approach 30

31 Key Features Oversized non- insulated piping allows for balancing storage of heat energy Controlled by temperature and pressure in DES pipe loop Designed for 70% of peak load Provides 98% of annual DHW and space heat for WAV 31

32 WAVDESS Costs Total Capital Annual Financing 3% net discount rate Annual O&M Annual Cost Energy Production Unit Energy Cost $2.97 million $170,000 $37,000 $207,000 20,000 GJ/year $14/GJ (incl. heat pumps) 32

33 Reasons Why Sewer Heat May Be Right For You Can jumpstart sustainable energy for communities Makes use of a wasted resources Reduces GHG emissions Reduces energy costs Enables the practical use of reclaimed water Economic development opportunity 33

34 Questions? Chris Johnston, PEng Vice President Kerr Wood Leidal Associates Ltd Erik Lindquist, PEng Senior Project Engineer DEC Mechanical Design Consultants Ltd or