Scientists at the University of California, Riverside, have found that while hybrid construction machines reduce fuel consumption and greenhouse-gas emissions, they produce more smog-forming gases than their non-hybrid counterparts.
The school's two-year, $2-million study, funded by the California Air Resources Board, evaluated the Caterpillar D7E dozer and the Komatsu HB215LC-1 hydraulic excavator in various field trials. In the tests, the machines demonstrated savings of up to 28% in fuel while emitting up to 21% more nitrogen oxides, or NOx, compared to traditional, non-hybrid equipment.