Optimisation of pumping and storage design through iterative hydraulic adjustment for minimum energy consumption

Figures & data

Figure 1. Graphical determination of required storage volume (Smet et al., 2002).

Figure 2. Water storage volume composition (Trifunović 2020b).

Figure 3. Tank and pump response to 100%, 75% and 50% of network balancing volume.

Figure 4. Single-point pump curve for duty head, H_D, and duty flow, Q_D adapted from Rossman, (2000b).

Figure 5. Variable speed setting, N, such that pump operates at average flow, Q_D.

Figure 6. SCOPE flowchart.

Figure 7. Example balancing tank response to a 4h power outage.

Figure 8. Graphical representation of SCOPE’s step 3 procedure with quasi code.

Figure 9. Nametown network layout (most critical node: e05 = 20.08 mwc @ 6:00 AM), adapted from Trifunović (2020b).

Figure 10. Nametown SCOPE processed results for total annual expenditure and pumping energy consumption for each possible tank location.

Figure 11. Optimised decision variables where (a) shows the SCOPE determined pump variable speed pattern, (B) shows the SCOPE determined tank position and pipe diameters and (C) shows GA post-processed pipe diameters.

Table 1. Decision variables and resultant financial summary for SCOPE and GA post-processed Nametown network (in EUR).

Decision Variable/Cost Component			Network Variant
			Nametown - Original	SCOPE-Processed	GA Post-Processed
Decision Variable	Tank Location		-	c01	c01
	Tank Elevation		-	26.6m	26.6m
	Tank Balancing Volume		-	1,470m^3	1,470m^3
	Tank Emergency Volume		-	1,110m^3	1,110m^3
	Pump Duty Flow		540m^3/h	370m^3/h	370m^3/h
	Pump Duty Head		65m	34.8m	34.8m
	Pump Variable Speed Pattern		-	Refer Figure 11 (A)	-
	Pipe Diameters		Refer Figure 9	Refer Figure 11 (B)	Refer Figure 11 (C)
Cost Component	CAPEX	Pipes	2,434,649	2,584,543	2,243,529
		Pumping Station	1,227,730	907,505	907,505
		Tank	-	637,818	637,818
		Sub-Total	3,662,379	4,129,866	3,788,852
		Loan Repayment	319,303	360,061	330,329
	OPEX	Operation	126,388	61,326	69,717
		Maintenance	36,728	36,175	35,084
Total Annual Expenditure			482,419	457,562	435,130

Table 2. Baseline cost for the proposed Dili WDN (in USD).

Component	CAPEX	OPEX			Annual Expenditure
		Loan Repayment	Energy Consumption	Maintenance
Pipes	20,590,793	1,795,199	-	102,954	1,898,153
Valves	588,040	51,268	-	-	51,268
Tanks	7,123,919	621,096	-	56,991	678,087
Pumping stations	3,638,923	317,258	3,585,843	72,778	3,975,880
Total Annual Expenditure:					6,603,388

Figure 12. Partitioned Dili WDN.

Figure 13. Dili RHS Main network SCOPE results.

Table 3. Comparison of the original and SCOPE processed parameters for the Hera pumping station.

Hera Summary	Original Configuration	SCOPE Optimised	Cost Savings
Duty Flow (m^3/h)	750	724
Duty Head (m)	300	157
Annual Energy Consumption (kWh/year)	7,070,044	3,626,555
Pump Investment Cost (USD)	1,948,035	1,894,725	−53,310
Annual Energy Cost (USD)	2,969,419	1,523,153	−1,446,266
Annual O&M Cost (USD)	38,961	37,894	−1,066
Total Annual Savings:			−1,500,642

Figure 14. Dili RHS Main SCOPE + GA post-processed pressure distribution.

Figure 15. Optimal location of the Dili network’s balancing tanks, as determined by SCOPE.

Table 4. SCOPE optimised Dili network financial summary (in USD).

Component	CAPEX	OPEX			Annual Expenditure
		Loan Repayment	Energy Consumption	Maintenance
Pipes	20,852,258	1,817,995	-	104,261	1,922,256
Valves	529,480	46,162	-	-	46,162
Tanks	8,069,914	703,572	-	64,559	768,131
Pumping stations	3,113,037	271,409	2,071,802	62,261	2,405,471
Total Annual Expenditure:					5,142,021

Table 5. GA optimised Dili network financial summary (in USD).

Component	CAPEX	OPEX			Annual Expenditure
		Loan Repayment	Energy Consumption	Maintenance
Pipes	18,996,000	1,656,158	-	94,980	1,751,138
Valves	529,480	46,162	-	-	46,162
Tanks	8,069,914	703,572	-	64,559	768,131
Pumping stations	3,113,037	271,409	2,074,078	62,261	2,407,748
Total Annual Expenditure:					4,973,179

Smet, Jo, C. van Wijk-Sijbesma, and and IRC International Water and Sanitation Centre. 2002. Small Community Water Supplies: Technology, People and Partnership. The Netherlands: IRC International Water and Sanitation Centre.

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Rossman, L.a. 2000. “Epanet 2.” September, 104. http://www.epa.gov/nrmrl/wswrd/dw/epanet.html.

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Trifunović, N. 2020a. Introduction to Urban Water Distribution: Problems & Exercises. CRC Press.

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Data availability statement

All data, models and code that support the findings of this study are available from the first author upon reasonable request.