Free energy survey leads to savings of £17,000 per year

When a major animal feed manufacturer, employing 200 people across the UK and producing over 34,000 tonnes of product every year from its Merseyside plant, explored energy-saving opportunities, the first company contacted was Rewinds & J Windsor, an Official Drives Partner for Control Techniques inverters.

Electricity consumption at the Merseyside plant was close to 94,000 per year and, as prices are to rise even further, the company tasked RJW with a site-wide energy-reduction survey. This survey - and the cost analysis software specially written by Control Techniques - identified twelve motors and motor/fan units that offered potentially the greatest payback.

Once the go-ahead was given, twelve drive panels containing Commander SK inverters were built at RJW's panel building department and installed by the company's site installation team. The drives varied in size from 5.5kW to 37kW, with an average size of 15kW.

By using inverter drives instead of other methods of controlling airflow, it was possible to reduce the speed of the motors running the fans, thereby reducing the motors' energy consumption. The saving made is equivalent to the square of the speed reduction, meaning that a speed reduction of only 20 per cent (which is usually possible) creates close to a 50 per cent energy saving!

Rapid payback

Significant results have been shown following a suitable period for analysis. The initial saving from the 14,000 investment was a 17,000 reduction in electricity costs, giving a payback period of less than one year - which is what RJW's calculations had predicted during the planning phase of the project.

This relatively small investment has had a noticeable effect on the electricity usage for the plant as a whole, reducing consumption to 77,000 and lowering the cost per tonne of end product by 18 per cent.

Additional benefits have been reported by the site's engineers, with greater plant reliability attributed to the introduction of the drives, which, in turn, has created maintenance savings through reduced downtime. The local environment has also benefitted with machines running quieter.

With a boost in production planned, plant energy efficiency gains per unit of product are expected to be even greater than before, while helping to control the inevitable rise in electricity costs.

Contact RJW for more information about free energy surveys.