Electric vehicles are green – under certain operational conditions

September 14, 2015 // By Christoph Hammerschmidt
Electric vehicles are considered as “green”, somehow. But how green are they really and which positive environmental effects can be attributed to them? A study from the Karlsruher Institut für Technologie (KIT) answers these questions.

Under which operational conditions have battery-electric vehicles a more ecological footprint than diesel vehicles? The RheinMobil project, coordinated by researchers from KIT, tried to find answers to these questions. The project analysed data generated in a fleet trial with 300.000 kilometres (about 185.000 miles) of electric driving. “The data show that battery-electric vehicles (BEVs) already today can be driven in a more cost-effective and at the same time more environmentally-friendly way than comparable vehicles with an internal combustion engine,” comments project leader Olaf Wollersheim. However, to achieve such a positive footprint, several prerequisites must be met. According to the data material, two usage categories can be regarded as ideal to achieve a positive ecological balance: Commuting and the usage as company car, as long as it also commutes between fixed locations.

“From the economical perspective, a high is the decisive factor,” explains Wollersheim. “However, for climate protection it is essential that the EV is charged to 100 percent with electric energy from renewable sources. Only then, electromobility is really sustainable”. In any case, users do not want to give up neither their comfort nor they are ready to change their mobility behaviour when they exchange their conventional car against an electric vehicle”.

The study did not only interpret the operational data of the vehicles and the charging columns, but also the answers collected in regular user polls. The results: To achieve the best ecological effect, it is ideal to combine high mileage with well-plannable individual tours over distance of maximum 100 kilometres each. Within the RheinMobil project, an average monthly mileage of 3500 kilometres has been achieved, which in turn required highly reliable vehicles and charging points was well as an exact prediction of the real energy consummation and charging behaviour.

According to the study, the ROI has been reached after some 200.000 kilometres of operation. The operating costs of the electric vehicles were significantly lower than those of conventional