SUSTAINABLE AND RESILIENT URBAN WATER SYSTEMS

Transcription

1 SUSTAINABLE AND RESILIENT URBAN WATER SYSTEMS Arka Pandit, Ph.D., John C. Crittenden, Ph.D., PE, NAE Brook Byers Institute for Sustainable Systems Georgia Institute of Technology Atlanta, GA Phone: (404) ;; Fax: (404)

2 URBAN WATER MANAGEMENT

3 Sustainable Water Resources Management

4 Typical Water Resources Demand Profile in an Urban Watershed Thermoelectric;; 39% Decentralized Energy Production Irrigation;; 39% Urban Farming Industrial;; 5% Aquaculture;; 1% Public Supply;; 13% Decentralized Water Production (LID) Mining;; 1% Livestock;; 1% Domestic;; 1%

5 Water Footprint of Agricultural Products

6 Water for Energy and Energy for Water in US Water for Energy Thermoelectric power generation accounts for ~ 52% of fresh surface water withdrawals. The average (weighted) evaporative consumption of water for power generation over all sectors is around 2.0 Gal/kWh. Energy for Water About 4% of the total electricity consumption in the US is for the water and wastewater sector1 Of the total energy required for water treatment, 80% is required for conveyance and distribution Energy Source Gal/kWh (Evaporative loss) Hydro Nuclear 0.62 Coal 0.49 Oil 0.43 PV Solar Wind Water Treatment* Surface Water Treatment 220 Groundwater Treatment 620 Brackish Groundwater Treatment kwh/mgal 3,900-9,700 Seawater Desalination 9,700-16,500 *Includes collection but does not include distribution

7 Water for Everything: Consequence in the Southeast US Principle Water Uses ACT ACF Savannah Purpose of water use Summer (in bgd) Winter (in bgd) Irrigation Municipality* & Industries Thermoelectric *Municipal use include residential water supply ACF, ACT & Savannah River Basin Since water use is higher in summer for all purposes there is a potential of conflict among different sectors in the event of water scarcity (agriculture, ecosystems) River Basin Apalachicola- Chattahoochee-Flint (ACF) Alabama-Coosa- Tallapoosa (ACT) Shared by AL, FL, GA AL, GA Savannah GA, SC Power plants supported 6 fossil fuel plants 6 fossil fuel and 1 nuclear plants 3 fossil fuel and 2 nuclear plants.

8 Water for Primary Energy in US Water for Fuel Extraction and Processing

9 Increasing Trend: Water Need for Transportation Water for Transportation: Impact of Biofuels Impact of Automobile Electrification The water footprint for biofuels may be 10 to 1000 times higher than conventional gasoline on a life-cycle per vehicle mile travelled basis depending on whether the feedstock crops are irrigated or not If all personal transportation in the metropolitan Atlanta, GA region was electric, the increased water demand (evaporative loss) needed to produce the electricity (under present generation mix) to charge the fleet of electric vehicles would be almost identical to the current domestic demand (estimated at 100 million gallons per day)

10 Water for Transportation: Impact of Fuel Types and Vehicle Technologies (Source: Harto, C;; et al., Life cycle water use of low-carbon transport fuels, Energy Policy, 2010)

11 Water for Mobility Network: Vehicle Electrification Metro Atlanta, 2010 and 2030 Conditions Source: Jeffrey Yen (2011) A system model for assessing water consumption across transportation modes in urban mobility networks, Masters thesis

12 SYSTEMS APPROACH FOR URBAN WATER MANAGEMENT

13 Reductionism versus Systems Analysis There will always be room for engineering reductionism but the greatest sustainability gains in the 21 st century will be from systems analysis. Source: Pandit, A., Lu, Z., & Crittenden, J. C. (2015). Managing the Complexity of Urban Systems. Journal of Industrial Ecology, 19(2),

14 Technological Fix Versus Sustainable Engineering Solution (Systems Analysis) New York City Water Supply The New York City drinking water supply system is the largest unfiltered water supply in the US. It provides approximately 1.2 billion gallons of high quality drinking water to nearly one-half the population of New York State every day. New York City Watershed Agreement of 1997: Multiple stakeholder agreement;; one of the most successful Integrated Urban Water Management projects Avoided Cost of filtration: Estimated at between $8.0 to $10.0 billion in capital and ~$1.0 million daily operational. Water from the NYC Watershed is considered to be the "Champaign" of drinking water. Ashokan Reservoir, Catskill, NY;; (123 billion Gal, 255-square-mile drainage basin, 180 feet deep) Statistics: o Serves 9 million people o 3 Watersheds: Croton, Catskill (90% of the supply) and Delaware o 19 Reservoirs o 2000 sq. mile watershed extending 125 miles north and west of New York City o Most of the water is provided by precipitation (rain & snow).

15 Low Impact Development - LID Best Management Practices (BMPs)

16 LID: Flood Control Capability For extreme rainfall events (Atlanta) Return period Rainfall intensity, in./24hr 1-yr yr yr yr yr yr yr 7.92 Rain gardens occupying 11 % (R-1) ~ 16% (RG-6) of community size control 100 % of stormwater runoff generated in extreme rainfall events up to 8 in.

17 Water Flows within the Urban System with LID Implementation: Case Study of Atlanta, GA Individual water use (91 Gpcd) in 2-story apartment (RG-1) Implemented LID technologies: rainwater harvesting, grass pavement, rain gardens, and xeriscaping Reduces dependence on the centralized potable water system by ~50% (entire non-potable demand) Uncontrolled Stormwater runoff (kgal/cap-yr) : 16 0 Smaller Water Treatment Plant Same Size Waste Water Treatment Plant Unit: Gallon per capita per day (Gpcd)

18 Life-Cycle Analysis of LID Techniques for Stormwater Management % of annual world average environmental load per capita CI with CSS CI with SSS Wastewater (CWTS) Rainwater harvesting Stormwater (SSS) HI CI with CSS CI with SSS HI CI with CSS CI with SSS HI CI with CSS CI with SSS R-1 R-5 RG-1 RG Person/acre 16.9 Person/acre 14.7 Person/acre Person/acre Infrastructure Type Water (CWSS) Stormwater (CSS) Stormwater (rain garden) CWTS: centralized wastewater treatment system;; CWSS: centralized water supply system;; CSS: combined sewer system;; SSS: separate sewer system CI: Centralized Infrastructure HI: Hybrid Infrastructure (Centralized+ LID) HI

19 Typical Greywater Reclamation System at the Household Level Source: Note: N.S.W. denotes New South Wales, Australia

20 Water Flows within the Urban System with Reclamation Option: Case Study of Atlanta, GA Individual water use (91 Gpcd) in 2-story apartment (RG-1) Smaller Flow, More Concentrated;; Smaller Plant: Good for better energy and nutrient recovery.

21 Energy Required for Greywater Reclamation with Membrane Bioreactor Electricity consumption (kwh/kgal) R-1 ~ R-5 RG-1 RG-2 RG-3 RG-4 RG-5 y = x R² = E E E E E+02 Membrane bioreactor (MBR) treatment capacity, kgal/day

22 Comparative Life-Cycle Analysis of Centralized and Hybrid Infrastructure (CI and HI) % of annual world average environmental load per capita CI HI CI HI CI HI CI HI CI HI CI HI CI HI CI HI CI HI CI HI R-1 (1.6) Stormwater runoff Wastewater Water Reclaimed water R-2 (3.1) R-3 (7.2) R-4 (13.8) R-5 (16.9) RG-1 (14.7) Zoning code (people/acre) Hybrid Infrastructure combines Greywater Reclamation for nonpotable use with centralized supply for potable use only. RG-2 (31.6) RG-3 (63.2) RG-4 (135.2) RG-5 (290.4)

23 Potential of Water Supply by Combining Greywater Reclamation & Rainwater Harvesting Total water demand % supplied by greywater reclamation % supplied by rainwater harvesting % supplied by greywater reclamation and rainwater harvesting % Total water demand, MGal/yr % 120% 100% 80% 60% 40% 20% Relative % to total water demand 0.1 R1 (1.6) R2 (3.1) R3 (7.2) R4 (13.8) R5 (16.9) RG-1 (14.7) RG-2 (31.6) RG-3 (63.2) RG-4 (135.2) RG-5 (290.4) 0% Zoning code (people/acre)

24 System-based Benefits of LID Best Management Practices

25 RESILIENCE OF URBAN WATER SYSTEMS

26 Challenges in Urban Water Infrastructure Leaching from pipes Earthquakes Non-existent Infrastructure Leaking Pipes Increasing Demand Drought Flood Terrorism Limited Availability

27 FRAMEWORK TO QUANTIFY RESILIENCE

28 Indices to Address the Criticalities Five indices were developed to concurrently address all the criticalities in an UWS at a system-level. These indices are interconnected and address multiple criticalities simultaneously. Availability of Resource Reliability of Supply Water Quality Index of Water Scarcity (IWS) Index of Network Resilience (INR) Water Quality Index (WQI) Relative Dependency Index (RDI) Relative Criticality Index (RCI)

29 Index of Water Scarcity (IWS) IWS IWS rel abs = ( wts, + was, + wis, + wms, ) + ( wag, + wmg, ) S W + G W {( wis, + was, ) ( wts, el) + ( wms, rf) } ( wag, + wmg, ) 1 = + 2 SW G W w t,s : surface water withdrawal for thermoelectric cooling;; w a,s : surface water withdrawal for agriculture;; w i,s : surface water withdrawal for industrial purposes;; w m,s : surface water withdrawal for municipal supply;; w a,g : groundwater withdrawal for agriculture;; w m,g : groundwater withdrawal for municipal supply;; r f : return flow from residential supply;; e l : evaporative loss from thermoelectric cooling;; S W : total availability of renewable surface water;; G W : total availability of renewable groundwater

30 Water Quality Index (WQI) WQI 7 = q i= 1 i q i denotes the value of the water quality parameters on a scale of 0 to 1 depending on their concentration and MCL, MRDL or the recommended range. Parameter MCL/MRDL Total Coliform Bacteria 0.0 Fluoride (ppm) 4.0 Chlorine (ppm) 4.0 Nitrate as Nitrogen (ppm) 10.0 Total Trihalomethanes (TTHM) (ppb) Total Haloacetic Acid (HAA5) (ppb) Range ph

31 Index of Network Resilience (INR) Developed through analysis of network topology. Provides an indicator about how the topology affects the resilience of the network. The INR is calculated through a MCA model considering the following six graph properties: Graph Diameter (d) Characteristic Path Length (l) Central-point dominance (c b) Critical ratio of defragmentation (f C ) Algebraic Connectivity (λ 2 ) Meshedness Coefficient (r m ) The first two attributes are related to the efficiency of the system, the third reflects the dominance of a particular node in maintaining the integrity of the network, and the last three are surrogate measures of the robustness and path redundancy of the network to failure of one or more nodes or links

32 Relative Criticality Index (RCI) Represents the criticality of distribution system based on the pipe material. Indicates the attention required for each pipe type Allows prioritization of resource allocation according to these criticalities RCI = R x + C x + E x ( ) ( ) ( ) j j j j x: is the distribution system in discussion;; R j (x): is the reliability component of pipe type j;; C j (x): is the Cost function of pipe type j, and E j (x): is the Energy function of pipe type j.

33 Relative Dependency Index (RDI) The RDI comprises of two metrics, 1) percentage of residents having dual source of supply (ζ), and 2) the percentage of residents (in the urban area under purview) connected to the largest water treatment plant (ξ), i.e. if a city is supplied by three different plants with each having a share of 50%, 30% and 20% respectively, then ξ=0.50. RDI = 0.75ζ ξ ( ) RDI is a weighted sum of ζ and (1- ξ) with a greater weight assigned to ζ, since a higher proportion of people having access to multiple sources of supply increases the inherent redundancy of the system making it more resilient.

34 The Composite Index of Resilience for UWS (R-Index) ω 1 - ω 5 : ( ω IWS ω WQI ω INR ω RCI ω RDI ) = iff IWS, WQI, INR, RCI, RDI > 0 weighting factors assigned through social decision making for a particular system Determining the Weighting Factors: Since the indices developed in this study are interrelated, Analytic Hierarchy Process cannot be used to determine the weighting. Analytic Network Process (ANP), which allows for the inclusion of interconnections (dependence and feedback) between different criteria in decision making;; is used to determine the weights. ANP uses a network model having clusters of elements (criteria and alternatives).

35 The Temporal Dimension of Resilience Severity of Perturbation: f(d f,s f ) Design Phase Governed: Robustness, Redundancy, Better Layout Speed of Recovery: f(s r ) Operation Phase Governed: Resourcefulness, Rapidity

36 INFRASTRUCTURE ECOLOGY Source: Pandit, A., Brown, H., Newell, J. P., Chang, M. E., Weissburg, M., Xu, M., Crittenden, J. C. (2015). Infrastructure Ecology: An Evolving Paradigm for Sustainable Urban Development. Journal of Cleaner Production, doi: /j.jclepro

37 Interconnection between Urban Infrastructure System, Natural Environmental Systems and Socio-Economic Systems

38 Infrastructure Ecology: Concept and Definition Urban infrastructure systems are analogous to ecological systems because they are interconnected, complex and adaptive components that exchange material, information and energy among themselves and to and from the environment. Analyzing them together as a whole, as one would do for an ecological system, provides a better understanding about their dynamics and interactions, and enables system-level optimization. The adoption of this infrastructure ecology approach will result in urban (re)development that requires lower investment of financial and natural resources to build and maintain, is more sustainable (e.g. uses less materials and energy and generates less waste) and resilient, and enables a greater and more equitable opportunities for the creation of wealth and comfort.

39 12 Principles of Infrastructure Ecology 1. Interconnect rather than segregate 2. Integrate material, energy & water flows 3. Manage inherent complexity 4. Account for systems dynamics 5. Decentralize to increase response diversity and modularity 6. Maximize sustainability and resilience of material & energy investment 7. Find synergies between engineered & ecological systems 8. Take stakeholder preferences into account 9. Maximize the creation of comfort & wealth 10. Take advantage of socioeconomics as a driver in achieving change. 11. Require adaptive management as the policy strategy 12. Utilize renewable flows rather than depleting stocks

40 INFRASTRUCTURAL SYMBIOSIS Saving Water by Switching to Decentralized Energy Production: Combined Heating, Cooling and Power (CCHP)

41 Recapturing Lost Heat in Combined Heat & Power System Heating Cooling Air-cooled Microturbine Absorption Chiller Eliminates the need of Water for Energy Electricity

42 Projected Growth Scenarios for Atlanta Business As Usual Year 2030 More Sustainable Development Year 2030

43 Atlanta Energy and Water Demand Projections for More Compact Development (with low flow fixtures + decentralized CCHP system) GWh ,000 69% reduction 12,700 MGD (Million Gallons per day) Withdrawal 63% reduction Evaporation 60% reduction Electricity from Grid Electricity from Grid with CHP 0 Electricity from Grid Electricity from Grid with CHP 0 Electricity from Electricity from Grid Grid with CHP Residential and Commercial Electricity Demand (with Air Cooled Microturbines in a Decentralized CHP system) Water Demand (Withdrawal) Water Consumption (Evaporation)

44 Potential GHG and Cost Reductions in 2030 By 2030, implementation of CHP in all the residential and commercial buildings (new and existing) will reduce the CO 2 emissions by~ 0.04 Gt CO 2. and the energy costs by $1.1 billion per year for the Metro Atlanta region. CO 2 Emissions (Million tons CO 2 ) Emissions(Electricity) -45% Emissions (Thermal) 6 78 Assumptions: The costs reduction calculation is only based on the cost of natural gas and the cost of electricity from firms in the region. The 2030 grid+chp scenarios assumed residential and commercial units in the base year were also retrofitted with CHP systems 0 Energy from Grid with Energy from Grid CHP CO 2 Emissions

45 INFRASTRUCTURAL SYMBIOSIS Harnessing the synergistic benefits of coupled urban infrastructure systems

46 The Connection between Autonomous Vehicles and Water

47 The Synergistic Effects of Infrastructural Symbiosis Low-Impact Development Greywater Reclamation Rainwater Harvesting Air-cooled Microturbine Residential PV, Wind, etc Thermal and Energy Storage Vehicle-to-Grid (V2G) Transit oriented Development Decentralized Water Infrastructure Decentralized Energy Infrastructure Increased Neighborhood Amenities Mixed Land Use Preferred Neighborhood Compact Growth The accumulated synergistic effects : reduced water and energy consumption, lower dependence on centralized systems, larger share of renewables in the electricity mix, reduced vehiclemiles travelled, & an increase in tax revenue. Autonomous Vehicles

48 Summary Sustainable water resources management needs to consider all sectors that exert demand on a watershed. Decentralized stormwater management using Low Impact Development can control the runoff of a 100-yr rainfall event. Combining rainwater harvesting with greywater reclamation can supply 100% of water demand for single-family residences, and 60% water demand for multi-family homes. Significant water savings can be achieved through switching the mode of energy supply. The R-index addresses resilience of urban water systems in both the short-term, i.e. its capacity to withstand shocks like earthquake, pipebreaks, etc. as well as and long-term resiliency, like the capacity of the system to cope up with increasing population or a gradually changing climate pattern.

49 THANK YOU!!! Arka Pandit, PhD Research Faculty, School of Civil & Environmental Engineering Georgia Institute of Technology