It has been reported that replacing an existing rotor with a new rotor that is optimized for power consumption reduces the rotor motor electricity consumption by 10 to 30%.
In one US based mill, the installation of a new 500 hp high efficiency re-pulper rotor reduced electricity consumption by 23%.
In another mill in Canada, tests with a high-capacity, aerodynamic, variable speed pulping rotor resulted in electricity savings of more than 50%. Projected annual savings amounted 3.9 GWh (Kramer et al., 2009. p.97).