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Energy savings as a service

09 March 2023

AS PART of an innovative energy-savings-as-a-service partnership, Rockwell Automation's drive technology has helped reduce emissions and deliver substantial annual energy savings at the Sibanye-Stillwater Driefontein mine in South Africa.

Rockwell Automation and Energy Drive, an energy-efficiency specialist with headquarters in Durban, South Africa, recently signed a memorandum of understanding in which they will collaborate on projects that are designed so that the resulting energy savings offset any investment in technology and systems required to drive the sustainability solutions.

“We share a common vision to provide the most efficient and sustainable solutions for customers and the environment,” said Tom O'Reilly, global vice president, sustainability, at Rockwell Automation. “We are excited to address the rapidly growing needs of our customers with this energy-saving-as-a-service partnership, to help them on their journey to greater sustainability and achieving net zero.”

Designed by Energy Drive, the system at the Sibanye-Stillwater mine is central to the new optimised control solution for the mine’s ventilation architecture. The new efficiencies – which have delivered annual energy savings of more than 55 GWh – will help Sibanye-Stillwater address some core goals of its ESG activities.

“Collaboration is at the core of our business, and actualizing sustainability is what drives us,” explains James Hynd, CEO of Energy Drive. Describing ‘actualizing sustainability’, Hynd explains that a direct result of the energy savings we deliver is the reduction of CO2, which contributes to our clients’ sustainability targets, specifically carbon-reduction targets.” As a result, Energy Drive operates as a resource to energy-intensive industries, helping with their response to operational outputs and sustainability targets driven by investment committees.

The ventilation system’s operational parameters have been remodeled to leverage the advanced capabilities of Rockwell Automation’s PowerFlex® 6000T variable-frequency drives. Through optimized control of fan speed and air circulation, this new approach has resulted in an average energy saving of 62% in one shaft and 48% in the other, with another shaft soon to be commissioned.

Engineers anticipate that the three upgrades will eventually deliver a total energy saving of about 360GWh over the term of the contract - equivalent to removing 5000 South African homes from the grid every month. Notably, it will save 379,000 tons of carbon over the period, while significantly reducing water and coal consumption.

Thomas Malomane, power control business manager, Africa, at Rockwell Automation, explained: “A large proportion of global energy is consumed by electric motors, with HVAC applications accounting for a significant part of this. Many motor-based solutions are either running without any form of motor control or are using outdated technology and practices that do not offer contemporary efficiency capabilities. Our PowerFlex range of variable-speed drives undergoes continual development to address modern demands and is a core solution for reducing energy consumption across a huge variety of applications globally.”

Volatile energy prices compounded by global sustainability initiatives have delivered the perfect justification for greater energy efficiency; and significant savings can be made with the correct deployment of motor control solutions. In most cases, the purchase cost of a motor is eclipsed by its lifetime running costs, so any means to keep running costs down will not only deliver faster payback, but also help users to address ever-more stringent ESG targets.