Feature articles 2006
Hybrid electric vehicle made possible
Elizabeth Latham, Electroline journalist
The electric car has been a dream in the pipelines since the early 19th century but has always seemed out of reach because of battery life, cost and weight. Now a hybrid electric vehicle has been made possible with the development of a long-life battery by Technology Research Laboratories (TRL) in the US.
The battery operates on chemistry principles different from those of conventional batteries. The new device uses materials that are plentiful, inexpensive and claimed to be far less polluting than other storage devices.
The battery is made almost entirely of carbon and plastic and can withstand severe electrical abuse, including total discharge or disuse for a long time. It uses salts of inorganic materials in an aqueous solution. These are very inexpensive, abundant and relatively safe substances such as salts of iron and sodium.
An immediate and attractive application is the 'plug-in' hybrid-electric car. These cars have been around for years, but until now the power sources have been unreliable. The TRL battery provides a means to achieve hybrid electric vehicles with a range of 120+ km per charge.
Tests from TRL confirm that a typical four-passenger electric car powered by less than 453 kg of TRL batteries would have a range of 120-160 km depending on speed and road conditions.
For the hybrid design approach to have a significant impact on 'fuel consumption', the range of the hybrid operating solely on battery charge must be a typical distance for a large number of motorists.
That range is probably in the order of 160-240 km a day, including some margin for unusual amounts of travel. With such performance, the hybrid car could be driven on battery power most of the time, and the internal combustion engine used only for extended trips.
The battery also has applications for standalone wind or solar power systems and power station load levelling. Other potential uses for the long-life battery range from small power supplies for remote lighting to the EV and utility load levelling.
The time it takes the battery to charge depends on design. For high drain rate it could be charged in minutes. In others, such as long-term storage for emergency and UPS use, it could take 10 to 30 hours.
One of the primary features of the battery is its long life. Its total operating lifetime in cycles or years is already at a million cycles, representing 20-30 years.
Another feature of the battery is that it has no impact on the environment when disposed of, according to Ralph Zito, R&D director, Technology Research Laboratories, although he does note that others might argue the large-scale effects of plastic and carbon waste.
"There are no particular handling requirements. The battery can be left on either discharge or charged state for years with no ill effects. Cycling does no harm either, as long as certain cell voltages are not exceeded. But, the appropriate battery energy circuitry would take care of that," Zito said.