Zero emissions on short-distance trips thanks to battery power
In principle, the electric drive using a battery as an energy accumulator is an interesting alternative drive system. It is quiet and gives rise to no emissions at all during vehicle operation; furthermore, if the electricity is produced from renewable resources, it is also CO2-free over the entire function chain. It is handicapped by heavy and costly batteries which significantly restrict its operating range or render it suitable for local or regional use only.
Daimler-Benz became a leader in battery technology back in 1998 with the development of the ZEBRA (Zero Emission Battery Research Activity) high-energy battery. In the course of laboratory testing, this withstood simulated mileages of some 200,000 kilometres without complaint and had already demonstrated its durability in real-world use over distances well in excess of 100,000 kilometres.
The main components of the ZEBRA battery were sodium chloride (common salt) and nickel. Operational at temperatures of 270° to 350° Celsius, it had four times the energy density of a conventional lead battery, was shock-resistant, and could be recharged at any time without succumbing in the long run to the dreaded "memory effect".
Safely installed in the underfloor section of the Mercedes-Benz A-Class, these batteries were protected in the event of an impact and left the full interior space of the vehicle to the occupants. Performance also was extremely respectable: from standstill, the Zero Emission Vehicle accelerated to 100 km/h in just 16.5 seconds thanks to a powerful asynchronous motor. But 200 kilometres later, however, it would be time to recharge the 370 kg ZEBRA battery. Despite highly efficient charging devices and rugged batteries the recharging time was simply too long.
From an environmental policy angle, battery-powered vehicles are only a stopgap measure, because many of the power plants which provide the electricity used to charge the batteries still generate pollutant emissions. Nevertheless, Mercedes-Benz offers battery-powered electric vehicles for particularly sensitive applications in the van sector.
Hybrid drives and, in the longer run, fuel cell vehicles which generate their electricity on board afford clearly better alternatives in terms of driving dynamics and efficiency.
