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Why VSDs are a crucial waypoint on the route map to Net Zero

The UK water industry has unveiled its plan to deliver a Net Zero supply for customers by 2030, a full two decades before the government's target of 2050. The sector deserves immense credit for setting such an ambitious target, which is the world's first sector-wide commitment of its kind. Getting there will not be easy, but as ABB's Clayton Mead explains, embracing the quick wins now can help to lay the foundations for success in longer term goals.

Water is the UK’s fourth most energy-intensive industry, and most of this energy is consumed in electricity. There is no single solution to achieving Net Zero on its own; it requires behavioural, organisational, environmental and technological change on an unprecedented scale, and at breakneck speed. Renewable energy, low emission vehicles and processes, conservation and reducing leakage are all important elements, but they all need to be chipped away at simultaneously in order to make real progress.

The scope of the route map is vast, encompassing many different elements and approaches, and requiring collaboration across the whole industry and beyond. Some elements, for instance restoring native habitats, or switching to renewable energy sources, or lobbying government for more joined-up decision-making, will require large amounts of time, effort and investment. Some will utilise technologies and innovations that do not yet currently exist. However, there are some elements where a small change, using technology that is readily available today, can make a considerable difference. A case in point is the use of variable speed control on motor-driven processes. This can help to make substantial and rapid progress in shifting the CO2 dial downwards, while freeing up resources to concentrate on the longer term, big picture projects.

Variable speed drives (VSDs) can be leveraged in two ways to support Net Zero objectives in the water industry. Firstly, they can dramatically improve the energy efficiency of motor-driven processes and assets, particularly pumps. Pumps are a variable torque application in most cases, which means that, due to the Cube Law, any reduction in speed results in a proportionally higher reduction in energy usage. In practice, this means that running a pump at 80 percent speed uses only half the energy that it would require at full power. Many pumps do not need to be run at full speed all the time. Running each pump in a facility with variable speed control can therefore result in vast combined savings for only a comparatively modest outlay, with a typical payback time of between six months and two years.

Secondly, VSDs can reduce leaks and conserve precious water. Pressure is the main culprit in causing leaks, and a VSD can prevent many of them from occurring. Many pumping stations are set to operate on a program that runs the pumps at a steady, high speed until the pressure gets up to the desired level. The pumps will then turn off and turn on again once the pressure drops. This results in frequent starting and stopping, which in turn leads to more non-return values being activated, leading to pressure transients that can cause pipes and joints to crack. Furthermore, pumps are often oversized, with selection based on a worst-case scenario. By reducing the pressure, and controlling pump operation more smoothly, this spreads flow evenly and reduces the risk of high flow rates causing damage to pipes.

The road to Net Zero is long, its scope is ambitious, and with a finite time in which to achieve it the clock is already ticking. VSDs represent a quick and easy win that can make a big impact on energy efficiency and leakage reduction almost overnight. In conclusion, why wait until 2030 when VSD technology can help to make a difference right now?

For more information and resources about the energy saving potential of variable speed drives, visit: www.abb.co.uk/energy

ABB, in association with WWT, has also produced a WWT Explains guide, which looks at how improved water pressure management can be used to minimise the amount of water lost to leaks and bursts: WWT Explains - Pressure Management and Leakage

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