PLUGRISOST : A MODEL FOR DESIGN, ECONOMIC COST AND ENVIRONMENTAL ANALYSIS OF RAINWATER HARVESTING IN URBAN SYSTEMS

Transcription

1 IWA International Conference of Economics and Asset Management April Marbella PLUGRISOST : A MODEL FOR DESIGN, ECONOMIC COST AND ENVIRONMENTAL ANALYSIS OF RAINWATER HARVESTING IN URBAN SYSTEMS Xavier Gabarrell Sostenipra research group; Institute of Environmental Science and Technology, Department of Chemical Engineering of the Universitat Autònoma de Barcelona; X. Gabarrell, T. Morales-Pinzón, J.Rieradevall, M.R. Rovira, G. Villalba, A. Josa and C. Martínez-Gasol

2 INDEX IWA International Conference of Economics and Asset Management April Marbella 1- Objectives 2- Methods 3- Results and Discussion

3 OBJECTIVES To facilitate the economic evaluation and the potential environmental impact of alternative water supplies (rainwater harvesting (RWH) and greywater systems) at different scales of urban planning. To propose a dynamic approach as a tool for life cycle assessment of this system from the perspective of LCM and Dinamics Systems.

4 JUSTIFICATION A. It is necessary to develop tools that integrate sizing and Environmental Assessment of RWH systems. B. This research would helps to identify the potential environmental impacts attributable to these systems, as well as the economic analysis in urban areas. C. New strategies to integrate LCA and DS methodologies. Plugrisost analyses the optimal design variables, cost and environmental performance of RWH and greywater systems, using tap water production as a reference system for comparison. The use of economic and environmental indicators can make the optimal size of a rainwater tank more restrictive when it is compared to the results regarding the satisfaction of the demand for rainwater. Economic and environmental analysis can help avoid oversizing tanks for rainwater and thus obtain greater benefits, where the estimated cost and GWP are two good indicators included in Plugrisost for this purpose. Besides, () it includes several environmental impact indicators that are suggested LIFE10 ENV/ES/ in the lifecycle AQUAENVEC assessment.

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6 where: P precipitation (m3/d) CS catchment surface (m2) RC runoff coefficient FC filter coefficient Sc storage capacity of rainwater tank (m3) S(t-dt) water volume of rainwater storage tank at time t-dt (m3) t moment in time (d) dt interval of time between calculations

7 Catchment surface Rainwater catchment Rainwaterin storagetank Rainwater consum Greywater reuse Tap water consum Rainfall Storage volume Rainwater demand Greywater demand Tap water demand Water demand Causal model for technical analysis of RWH systems.

8 Storage volume Greywater Greywater in storage tank Greywater consum Tap water consum Rainwater consum Black water Causal model for technical analysis of Greywater systems.

9 Flows model for technical analysis of Rainwater systems.

10 Flows model for technical analysis of Rainwater systems.

11 stream, river, sea catchment water supply rainwater 1 2 catchment 5 subsystems 6 1 tap water production potable water treatment storage 2 3 rainwater harvesting domestic water uses 4 wastewater treatment water distribution water treatment/f iltration 5 urban water process 6 urban water management 3 distribution domestic uses graywater system rainwater transport waste water transported 4 agricultural/industrial uses sewage treatment sludge treatment transport treated effluent streams runof f

12 Life cycle assessmentframework Goal and scope definition Inventory analysis Interpretation Direct applications: Product developmentand improvement Strategicplanning Publicpolicy making Other Impact assessment Stages on LCA (ISO 14040, 2006).

13 Environmental interventions Row material extraction Emissions (in air, water and soil) Physical modification of natural area Noise Impact categories Climate change Resource depletion Land use Water use Human toxic effects Ozone depletion Photochemical ozone creation Ecotoxic effects Eutrophication Acidification Biodiversity Damage categories Human health Ecosystem quality Resource depletion LCA results Midpoints Endpoints Overall UNEP/SETAC scheme of the environmental Life Cycle Impact Assessment (LCIA) framework, from Ciroth et al. (2011).

14 Economic and financial analysis of RWH systems For the economic study a general list of materials required for the construction of a RWH system was developed. The labor required by a database specializing in construction was estimated using the database of ITeC (2011). A factor for maintenance of the RWH system was included. Four types of prefabricated tank material (steel, concrete, fiberglass polyester and polyethylene) in a range of storage capacity from 3 to 125 m3 according to the most frequent values by type of material found on the market, were selected. In each RWH system an adequate storage capacity was employed. As assumptions a steady increase in water prices and energy (used in pumping the RWH system) was assumed. Transport of materials was estimated as an average value per ton placed on work for a distance of 30 km. A sample of companies that specialize in providing water tanks, pumps and pipelines required were selected. Prices of similar products were calculated as average. Financial feasibility of RWH systems using indicators the net present value (NPV), the internal rate of return (IRR), the return of invest (ROI), the benefit-cost ratio (BCR) and the payback period (PBP).

15 Economic and financial analysis of RWH systems Transport of materials was estimated as an average value per ton placed on work for a distance of 30 km. A sample of companies that specialize in providing water tanks, pumps and pipelines required were selected. Prices of similar products were calculated as average. Financial feasibility of RWH systems using indicators the net present value (NPV), the internal rate of return (IRR), the return of invest (ROI), the benefit-cost ratio (BCR) and the payback period (PBP). Additionally, the cost of energy by default was 0.14 Euros/kWh, which is the referenced price in Spain (CNE, 2012).

16 We created a simulation model using system dynamics methodology. This model considers RWH potential and tap water as input flows to the system. Water consumption has been divided into two flows, potable water demand and rainwater demand. I( t ) = I( t dt) ( IDr IDp) dt I = I I Dr D = D r D p i I: Matrix of potential environmental impact of the system I Dr : Matrix of potential environmental impact of RWH I Dp : Matrix of potential environmental impact of tap water I i : Matrix of potential environmental impact by infrastructure I u : Matrix of potential environmental impact by energy use D: water system demand Dr: rainwater demand Dp: potable water demand u Each water flow, has been assigned the environmental impacts calculated for the equivalent of the functional unit considered throughout the system ENVIRONMENTAL IMPACTS: LCA classification and characterization stages have been considered. The method 2001 Baseline v2.04 CML has been used. The ecoinvent 2.0 database has been used, associated to the software SimaPro7.2.0

17 We have estimated the impact associated with consumption of tap water from the average consumption of inputs of water treatment plants. The impact of energy consumption was calculated on the basis of references or previous works. The life span of the rainwater storage tank, pipes and pumps is of 50, 25 and 15 years, respectively.

18 RESULTS AND DISCUSSION

19 RESULTS AND DISCUSSION

20 RESULTS AND DISCUSSION

21 RESULTS AND DISCUSSION Relationship between storage volume and RWH Rainwater Harvesting (m 3 year 1 ) RWH=2608.3ln(SV) R 2 =0.97 N_Pereira N_Bogotá Logarítmica (N_Pereira) y = 2,608.32ln(x) 4, R² = 0.97 RWH=404.7ln(SV) RWH=404.7ln(SV) y = ln(x) R² R 2 = = R 2 = Storage Volume (m 3 ) GWP could be substituted by storage volume? YES...then...

22 RESULTS AND DISCUSSION Relationship between storage volume and GWP (100a) CML 2001, Global Warming Potential (100a) [kg CO 2 eqv.] 480, , , , , , , , , ,000 GWP=2.37(SV) (SV)448,783.1 GWP=2.37(SV) y = 2.37x x (SV)448,783,1 448, R 2 =0.55 RR² 2 =0.55 = 0.55 GWP=16,3(SV) y = 16.30x x 2 2,458.1(SV)427, GWP=16,3(SV) 2 R² -2,458.1(SV)427,639.5 R 2 = =0.94 N_Pereira R 2 =0.94 N_Bogotá Polinómica (N_Pereira) Storage Volume (m 3 ) 2 GWP = asv bsv c b V e = 2a GWP: Potential Impact SV: Storage Volume Ve: Equilibrium Storage Volume a, b, c: constants

23 RESULTS AND DISCUSSION Proportion of total environmental impacts and contribution of the systems urban N1: Pereira N2: Bogotá N1: Pereira N2: Bogotá 11,850 m 3 3,806 m 3 15,250 m 3 3,921 m 3 15m 3 built -1 storage volume 85m 3 built -1 storage volume

24 IWA International Conference of Economics and Asset Management April Marbella PLUGRISOST : A MODEL FOR DESIGN, ECONOMIC COST AND ENVIRONMENTAL ANALYSIS OF RAINWATER HARVESTING IN URBAN SYSTEMS X. Gabarrell, T. Morales-Pinzón, J.Rieradevall, M.R. Rovira, G. Villalba, A. Josa and C. Martínez-Gasol Thank you!