ABB measures drives' ecological payback.

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With just half a day's use, a variable speed drive can compensate for the environmental cost of its own manufacture and disposal, a new study from ABB shows.

The study, carried out in cooperation with Tampere University of Technology, demonstrates how long drives of various sizes need to be used before they begin making a positive contribution to the environment.

The ecological payback was calculated for three ABB drives of 0.75 kW, 7.5 kW and 250 kW, respectively. The payback times were short in all instances, decreasing with higher power ratings. The 0.75 kW drive compensated for its global warming potential in 6 days; for the 7.5 kW drive it was 1.1 days and for the 250 kW drive it was 0.5 day.

By operating the drive for just half a day it is possible to avoid enough emissions to fully compensate for the carbon impact of manufacturing and disposal. The carbon footprint of the organisation then starts to shrink as the drive will continue to benefit the environment by saving emissions throughout its lifetime. An ABB industrial drive will typically provide a total lifetime saving of around 7,500 MWh or 3,800 tonhes of carbon dioxide emissions.

The ecological payback time is relevant to organisations that work to reduce their carbon footprint. A new installation will only start making a positive contribution to the environment after it has compensated for its own manufacture and disposal.

Variable speed drives are used in industry to control the speed of motor-driven machinery. Two-thirds of the total electricity consumption in industry is used for driving electric motors. Of this, an estimated 20% is wasted in throttling mechanisms that are used to regulate the flow of air and liquids. Using variable speed drives to control motor speed according to demand makes savings of up to 70% in energy consumption possible.

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