New study underlines short ecological payback of variable speed drives
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 savings of around 7,500 MWh or 3,800 tons 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.
“Investment calculations today are based on financial payback time – companies normally want their money back in two years or less,” says Steve Ruddell, ABB’s UK energy spokesperson and general manager, drives and motors.
“I believe that in five years’ time, there will have been a sea change in the way companies look at investment decisions and they will be just as keen to save CO2 as they are saving money today. Our study shows that using variable speed drives is one of the most cost-effective measures to achieve rapid and radical CO2 reductions.”
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.