The efforts to utilise and improve batteries-powered e-buses has displayed numerous downsides of this solution. Thus, the search for an alternative wireless electric solution has been stimulated. Such search has, among others, focused on another traditionally known power storage device – the capacitor.
Humanity has been using capacitors for more than a century and they are indispensable in many electric devices, a typical example being the photographic flash. There, the capacitor has turned out to be the perfect solution: incomparably short charging time at high charging current, capability for a momentary full discharge, practically unlimited life span and charging cycles.
Over more than a century capacitors, by implication, have been considered small and helpful where a shock discharge of current is needed. With the growing search for modern safe power storage devices this has changed. Leading international capacitors producers are now producing capacitors with unusually high storage capacity, also known as “ultra-capacitors”.
The real boost in ultra-capacitor technology, unexpectedly to many but otherwise following an inevitable logic, has come from China: the country where research and advancement in electrical energy solutions was defined as a national priority a few decades ago by an all-powerful political leadership and where the creative potential of a more-than-a-billion-large nation has been harnessed to service such priority.
Shanghai-based ultra-capacitor producer Aowei is selling on the market its second generation ultra-capacitor capable of storing 21 kWh within a volume of less than one m3, weighing less than one ton. If other international leading producers were to produce an ultra-capacitor of the same storage capacity, its commercially available top achievement would have a volume and weight seven times as high (!!) and 8.6 times the volume (!!). And this whilst Aowei is now already test-proving its third generation of ultra-capacitor which, within the same volume and weight, is capable of storing even more power.
Electric buses powered by Aowei’s ultra-capacitors have been running the streets of Shanghai now for more than seven years, having travelled more than eight million kilometers.