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Carbon Reduction, through efficient pump design - Case Study
Reducing carbon emissions is a subject that is high on the agenda for many companies within the utilities sector, and the water industry is no exception. It is estimated that 1% of the total UK CO2 emissions are created by pumping water around the country. Ofwat have created mechanisms within its framework to encourage water companies to seek further efficiencies by limiting the energy costs passed onto their customers. Thus, water companies are continually looking for ways to reduce their impact on the environment through operational efficiencies.
"... reducing the energy consumption of the site by over 11% significantly reduced costs and helped maintain our commitment to our customers to reduce our carbon footprint..."
There are many ways to reduce these energy costs, from encouraging customers to reduce demand and ensuring network leakage is minimised, through to high level actions, such as sourcing their energy from more sustainable origins. In this study, HydroCo investigate how one water company have reduced their carbon footprint through ensuring their pumps are operating as efficiently as possible.
Pump manufacturers play a vital role in this exercise, ensuring their pumps operate as efficiently as possible and are fit for purpose. The use of Variable speed drives also has an important role to play, ensuring the pumps use the least amount of energy for every m3 of water moved regardless of the ever changing hydraulic conditions which they are placed under. HydroCo's methodology combines innovative modelling techniques with the latest developments in pump design to deliver significant energy savings.
Initial Assessment
The water company in question relies solely on groundwater sources, pumping water from deep aquifers, up and into their water supply network. The initial phase of the study involved assessing which sources could yield the greatest efficiency savings; these sources were then weighted according to the ages / life cycle of the existing pumps and if any significant network, treatment, hydraulic changes had occurred since the pumps installation. A trial site was selected that fitted this criteria, and whilst is was not regarded as the most expensive sourceworks to operate, significant changes had occurred on site that had changed the hydraulic conditions the pumps were operating under.
"... the cost of the analysis and the new pumps could be recovered after just four years of use due to a reduction in energy .."
A small scale field test was conducted at a particular site monitoring both the hydraulic properties of the system as well as the pump efficiency and energy use.
Pump Modelling
A detailed model of the site was created, which not only considered the losses from the site pipe work, but also the borehole characteristics, key treatment apparatus and manufacturers' pump performance data. This detailed approach is not normally considered within a typical all mains network model build project and is only really possible using the latest features developed in the modelling software. The data from this field study was carefully collated and used to calibrate the detailed site model.
Detailed Analysis
Once the current system was modelled in detail, reflecting the existing site operation, it was possible to model many other manufacturers' pumps within the boreholes and assess them under a variety of operational conditions and measure their energy consumption. This enabled a detailed study into the most suitable pump for the site, not just for the given duty point, but under all operating conditions. This could then be related to preferred pump schedules considering other influences such as triad restrictions, or deployable outputs.
Conclusions
The study selected an alternative pump to the existing one thought, based on the estimated operational cost savings over a variety of hydraulic conditions. The selected pump yielded an 11% saving, representing a significant saving for our client and helping them keep their commitment to reducing their carbon footprint. The cost of performing the study and replacing the pump units was equivalent to the savings returned over a 4 year period, which has subsequently lead to the trial scheme being rolled out across the most energy hungry sourceworks.