Energy Efficiency in Cold Water Supply Systems Tool

Objective of the tool

To present energy efficiency increase, energy, CO2, CAPEX, financial savings and payback period due to the old ground cold water pumps replacement by a new and efficient in municipal cold water supply systems. After providing a minimal amount of input data, the tool converts data into a short report.

Target users. The representatives of national, local governments, municipalities, private companies, cold water supply utility companies and other decision-makers.

Why cold-water pumps replacement

Replacement of old and inefficient cold-water ground pumps in municipal cold-water systems are recognised as the “low hanging fruits” to highly increase energy efficiency with a very short and attractive 2-5 years payback period. The main barrier and bottleneck why the replacement of old cold-water pumps in municipal water supply systems does not happen is that most developing countries and countries with emerging economies do not have very precise and reliable data about their existing equipment and pumps, their age, flow rate, pressure head and other specific technical information of every device or cold-water pump. To collect these data, a very detailed technical audit should be performed, and municipalities do not have the necessary capacities, financial and human resources to perform this. Also, a detailed technical audit takes many months, and due to changes in the governance or staff, the moment can be lost. In the next stage, the detailed technical audit should be followed by an assessment of potential investment volume, so the final decision due to inefficient cold-water pumps would be taken, but the identification of potential investment volume is also an issue with existing capacities and human resources in municipalities.

How to remove barriers and bottlenecks

Therefore, there should be found a quick, reliable and easy way how to identify potential energy savings and investment volume from the existing data municipalities have. If the initial data shows a positive energy efficiency increase, acceptable investment volume and favourable payback period, then the principal high-level decision can be taken due to outdated cold water pump replacement, later followed by a detailed inspection of every individual equipment and pump, and tendering process to purchase this equipment. The practice shows that, for example, if the potential payback is around 2 years, then the very precise technical audit and equipment purchasing tendering process will improve accuracy by only a couple of months, defining a payback in limits of between 1.5 and 2.5 years, and this will not make and influence on an already taken decision due to outdated cold-water pumps replacement.

Tool to quickly identify the potential energy savings, investment, and payback

This developed online tool requires only minimal, limited data on cold-water consumption in municipalities and presents potential energy savings, CO2 savings, investment volume and a simple payback period. What makes a difference from other tools is that this tool identifies the potential investment volume and payback, other tools are missing to present. Having investment volume, energy, CO2 savings and payback period, the decision makers can take a decision due to the project implementation.

Methodology

The volume of cold-water consumption in a city is a key parameter in identifying the water average flow rate of m³/h. The water flow rate measured in m³/h or l/s varies depending on the daytime, season, consumers profile (residential, industrial, public, other) and are important parameters for selecting a specific individual cold-water pump to ensure enough cold-water supply during peak consumption time. In most cases, to increase reliability and to keep the highest energy efficiency level, for the cold-water supply point, instead of one pump, is used a set of pumps, depending on the cold-water demand from the consumer side, can be switched only 1, 2, 3 or more pumps. If one pump fails to operate, a few others are still in operation mode. This ensures that even during the lowest cold water demand, the utilised pumps are run with the highest efficiency. Therefore, this tool does not go into the details of how many pumps should be selected, as this is a task of a future deep dive engineering design process. The specific individual pump is also selected after the tendering process. Then the manufacturing company is selected.

Methodologically this tool utilises the energy amount kWh to pump 1 m³ of cold water. As the bigger pumps are more efficient in pumping 1 m³ of water, therefore the coefficients to adjust the energy amount kWh to pump 1 m³ of cold water depending on the pump size are applied in this tool. Due to the age and amount of pumped water, the hydraulic and electrical efficiency of the pump drops dramatically. Therefore, this tool calculates the total cold water pump efficiency drop and presents an amount of energy which will be saved by replacing old pumps. After selecting a specific country, the tool identifies the CO2 emissions factor for a selected country and converts energy savings MWh into CO2 savings. Energy savings also are converted into financial savings, investment and the simple payback period is presented.

Disclaimer

The function of this tool is merely informative, and the Copenhagen Centre on Energy Efficiency (C2E2) does not have any legal responsibility, interest or involvement in any of the technical nor financial recommendations that may be provided to the user. For more information, access our institutional webpage at https://unepccc.org/. Grundfos provided technical support for the development of the tool.