Applying the Water-Energy Nexus for Water Supply—A Diagnostic Review on Energy Use for Water Provision in Africa
Abstract
:1. Introduction
Research Scope
2. Methodological Approach
3. Results
3.1. Literature on Energy Use for Water Supply in Africa
3.2. Operational Performance of Water Utilities in Africa
3.2.1. Energy Demand as an Operational Performance Indicator in Africa
3.2.2. Data Required Energy Use for Drinking Water Supply
3.3. Drivers of Water Demand and Water Supply on Energy Use and their Relevance for Africa
3.3.1. Demand-Side Drivers
3.3.2. Supply-Side Drivers
4. Discussion
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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---|---|---|
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[40] | Provided a life cycle assessment of urban water provision and a comparison of the environmental consequences of treating virgin portable versus recycled water. | South Africa |
[52] | Assessed the sustainability of selected urban water treatment plants in Alexandria. | Egypt |
[41] | Provided a review of life-cycle assessments of the South African water sector, outlining the potential application of life-cycle assessments to improve efficiency of the water sector in the future | South Africa |
[43] | Explored the feasibility of using different alternative renewable energy options for clean water pumping. | Nigeria |
[13] | Assessed application of the water energy nexus in the MENA region, bearing in mind desalination as the treatment process. | North Africa |
[53] | Conducted a life cycle assessment of portable water production and associated impact to the environment. | Algeria |
[42] | Explored the use of solar powered pumps for rural water supply. | Ethiopia |
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[54] | Conducted a systems analysis to examine the energy requirements of the water supply for different alternatives of urban water supply. | South Africa |
[55] | Assessed the impact of variable energy prices on the financial stability of drinking water utilities in Accra and Ashanti regions. | Ghana |
[47] | Assessed the potential of high-capacity solar-powered boreholes compared to diesel-powered pumps in an emergency context. | Kenya, Somalia |
[56] | Provided the rationale for promoting energy efficiency for water utilities. | Tanzania |
[46] | Outlined the benefits of switching from fuel-powered to solar-powered pumps in refugee camps. | East and Horn of Africa |
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[57] | Provided a design for solar-power operated water pumping system for water provision in Niger Delta. | Nigeria |
[24] | Provided an energy and operational cost optimization model for seawater desalination. | South Africa |
[44] | Demonstrated the potential of small-scale photo-voltaic powered water treatment system for brackish-water to enhance water supply in remote areas. | Tanzania |
[25] | A life cycle assessment of desalination and mine-water reclamation as alternatives for portable water supply. | South Africa |
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Country | No of KPIs | Clusters of Key Performance Indicators (KPIs) | Literature Source |
---|---|---|---|
Kenya | 9 | Quality of service (3) Economic efficiency (3) Operational sustainability (3) | [67] |
Lesotho | 18 | Water quality (2) Customer care (5) Network disruptions (4) Continuity of supply (1) Metering (4) Water supply (2) | [69] |
Malawi | 11 | Access to water services (2) Sustainability of companies (4) Customer Care Service (3) Water quality (2) | [70] |
Nigeria | 16 | Level of service (6) Technical indicators (3) Financial indicators (3) | [63] |
Tanzania | 11 | Protection of users’ interest (3) Sustainability of the operator (6) Environmental sustainability (2) | [71] |
Uganda | 10 | Technical indicators (4) Financial indicators (3) Service indicators (4) | [72] |
Zambia | 15 | Operational indicators (5) Staff efficiency (2) Service level (3) Financial indicators (3) Corporate governance and management (2) | [49] |
Metric | Description | Remarks | Source |
---|---|---|---|
Ph5 (kWh/m3/100 m) | Standardized energy consumption. Assesses the average pumping energy use per unit volume at 100 m of head. | Provides information on minimum energy used. | [68] |
E1 (kWh/m3) | Energy in excess per unit of input volume Represents the potential for energy reduction per unit of total input volume. | Provides information on the impacts of energy management measures. No provision for the assessment of impact of leakage control measures. | [76] |
E2 (kWh/m3) | Energy in excess/unit of revenue water Represents the theoretical potential for energy reduction per unit of billed water. | Allows for assessment of impact of leakage control measures on the energy demand. Requires a hydrological model. | [76] |
WSEE | Water Supply energy efficiency Defined by the ratio between the minimum energy required by a pump and the actual energy used. | [74] | |
PEI kWh/ML/m | Pump energy indicator Normalizes the pump energy consumption against work done (pump operating hours). | Possibility to benchmark pump energy use for several utilities. Does not provide for the measurement of efficiency of individual pump stations. | [77] |
I1 and I2 (Structure, and quality) indicators (kWh/m3) | I1 shows the influence of the difference in elevation between source and consumers on energy demand. I2 shows the difference between actual energy used and the minimum energy required for water supply processes. | Do not require the use of complex hydraulic models. Do not consider frictional energy losses. | [80] |
Fi 10 (% cost of electrical energy) | Provides the percentage share of electricity cost as a proportion of total operational cost. | Provides information on cost trends useful for management decisions. | [68] |
D1 (€/m3 sold) D3 (€/m3 distributed) | Specific energy costs per volume of water sold. Specific energy cost per volume of distributed water. | D1 Provides cost estimates of energy for each billed unit of water. D3 estimates of energy cost (water distributed). | [81] |
D2, (€/m3 sold) | Specific energy cost in peak hours. | D2 provides cost estimates of energy during the peak hours/during high tariffs hours. | [81] |
D4, (kWh/m3 sold) | Specific energy consumption per volume of water sold. | Can be used to make an inventory of energy use for each pumping station/treatment plant. | [82] |
WNEE, Water Network Energy Efficiency | Ratio of the minimum required energy and the actual consumed energy. | [83] | |
UME, Unavoidable Minimum Energy | Minimum energy required at the tap. | Applicable to one or more pumps/pump stations. | [83] |
EEI, Energy Efficiency Indicator | Ratio between UME and the actual energy consumed by each device. | Accounts for the possible daily volume left in the reservoir (considered as excess energy). | [83] |
Water Type | Process | Energy Intensity kWh/m3 | City/Country | Reference |
---|---|---|---|---|
Mine water | Reclamation | 2.16 ** | South Africa | [25] |
Sea water | Reverse osmosis | 2.5–7.0 | Libya | [13] |
Sea water | Reverse osmosis | 3.69 | South Africa | [25] |
Sea water | Multistage flash distillation | 3–5 | Libya | [13] |
Surface water | Water supply | 0.29 | China | [87] |
Surface water | Water distribution | 0.41 | Toronto, Canada | [23] |
Surface water | Water distribution | 0.31 | Turin Italy | [23] |
Surface water | Water treatment | 0.07–0.21 | Chile | [27] |
Surface water | Water supply | 0.02 | Alexandria, Egypt | [52] |
Surface water | Water supply | 0.02–0.14 | Kenya | Macharia et al. (Unpublished) |
Groundwater | Water extraction | 0.14–0.69 | California, USA | [19] |
Groundwater | Water extraction | 2.87 | Florida, USA | [22] |
Groundwater | Water extraction | 0.32–0.47 * | South Africa | [58] |
Groundwater | Water abstraction | 1.1–2.4 | Kenya | Macharia et al. (Unpublished) |
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Macharia, P.; Kreuzinger, N.; Kitaka, N. Applying the Water-Energy Nexus for Water Supply—A Diagnostic Review on Energy Use for Water Provision in Africa. Water 2020, 12, 2560. https://doi.org/10.3390/w12092560
Macharia P, Kreuzinger N, Kitaka N. Applying the Water-Energy Nexus for Water Supply—A Diagnostic Review on Energy Use for Water Provision in Africa. Water. 2020; 12(9):2560. https://doi.org/10.3390/w12092560
Chicago/Turabian StyleMacharia, Pauline, Norbert Kreuzinger, and Nzula Kitaka. 2020. "Applying the Water-Energy Nexus for Water Supply—A Diagnostic Review on Energy Use for Water Provision in Africa" Water 12, no. 9: 2560. https://doi.org/10.3390/w12092560