Drives & Controls Magazine September 2023

30 n ENERGY EFFICIENCY September 2023 Energy saving as a service changes VSD business model Variable-speed drives (VSDs) have been a valuable tool for improving energy efficiency for many years. As we pursue greater sustainability in industrial operations, their appeal has grown stronger. While they were previously recognised primarily for their potential to improve process control with efficiency as a by-product, they are now an integral part of sustainability initiatives. Real-world fan and pump applications have traditionally been designed with extra capacity, and then restricted mechanically. This results in sub-optimal performance because the motors on these variable-torque applications run at design speeds, while the work being done by the fan or pump is controlled using dampers or valves to meet the process requirement. This is where VSDs can help. Driving a motor with a VSD allows the system to match the work done to that required by the system by changing the motor speed. By avoiding using partially-open dampers or valves, losses associated with them can be eliminated. This results in a massive reduction in energy consumption and helps users to reach their ESG goals. Cutting capital costs The two main drawbacks to the wider use of VSDs, particularly in some of the harder-toabate industrial sectors, have been their high upfront costs and uncertainty over their possible savings (and therefore ROIs). This could now be a concern of the past, thanks to a new collaboration between Rockwell Automation and Energy Drive, a company that originated in South Africa but now has its headquarters in London. The new approach – an energy-savings-as-aservice partnership – boosts sustainability while providing a more transparent and manageable resource and personnel model, and results in significant energy savings and emission reductions. Projects are designed so that the resulting energy savings offset any investment in the technologies needed to achieve sustainability. Rockwell VSDs are deployed in energy-saving systems designed and continually optimised by Energy Drive. In most cases, retrofitting a VSD system in this way can avoid the unnecessary expense and downtime of purchasing and installing new motors, reducing Capex and delivering greater net savings. Energy Drive specialises in partnering with companies in energy-intensive industries to achieve their energy-related sustainability goals. It removes the barriers to energy optimisation by taking on the risk, and partners with the organisations for the long term. By supplying the equipment, installing it, and ensuring that it runs effectively for as long as it is on a site, a turnkey sustainability installation can be achieved via a zero-Capex service contract. Energy Drive monitors the process data and the energy consumption of each of its customers’motors remotely (via third-party providers). This allows it to improve the performance of each installation continuously, as well as alerting the site to any potential issues. The reduction of CO2 resulting from the energy savings contributes to the organisation’s sustainability targets – specifically carbon reduction. For example, an energy-savings-as-a-service partnership of this type has been established at the Sibanye-Stillwater Driefontein gold mine in South Africa, where it is helping to reduce emissions and deliver substantial annual energy savings. The speeds of ventilation fans for two of the mine’s shafts are now controlled by Rockwell PowerFlex 6000T VSDs. After about a year, the installation has achieved average energy savings of 62% for the first shaft and 48% for the second. A third shaft will be commissioned soon. The upgrades are delivering annual energy savings of more than 55GWh and have helped the mine to address some of its ESG goals. Over the term of the contract, they will deliver energy savings of around 360GWh, equivalent to removing 5,000 homes from the South African grid. More importantly, 379,000 tonnes of carbon emissions will be avoided. The optimised systems have also reduced water and coal use significantly. Energy Drive controls the upgraded systems from the surface and monitors the systems 24/7 with pre-set alerts on critical conditions. If one of the fans fails, the system ramps up another automatically so that the health and safety of the miners working underground is never put at risk. Another benefit is improved equipment performance and maintenance. This innovative collaboration demonstrates how motor control systems such as VSDs can drive real-world sustainability, delivering energy efficiency, emission reductions and cost savings, while helping to achieve a more sustainable future. n A new energy-saving-as-a-service business model is helping energy-intensive industries to achieve sustainability goals using VSDs monitored and controlled by a third party. Giancarlo Scaturchio, Rockwell Automation’s customer sustainability manager for the EMEA region, explains how it works. South Africa’s Sibanye-Stillwater Driefontein gold mine is one of the first sites to implement the new energysaving-as-a-service model.