Ultracapacitor Buses – More Greener And Cheaper
22 October 2009 | Green Cars | No Comments
The search for more economical and fuel-efficient buses have led engineers from building hydrogen-fuel transit vehicles to hybrid-electric ones. But, as it turns out, the most environmentally-friendly and cheapest way to power buses proved to be the ultracapacitor buses. At least that is what a Chinese company, Shanghai Aowei Technology Development Company, and its partner for the U.S.A, Sinautec Automobile Technologies, states.
They started their experimentation with this technology three years ago, when 17 buses (with 41 seats) where set in motion on Shanghai’s streets, with phenomenal success, suffering no failures what so ever in this time frame. On Monday, 21 October they made a demonstration at the American University in Washington, DC with a ultracapacitor minibus.
In order to make the ultracapacitor buses work, they had to transform some of the bus stops into charge stations. In comparison to the common trolley buses, which need to touch the powerline all the time, the ultracapacitors only do this at the charge stations, placed three-five miles apart. Within a couple of minutes, the batteries placed under the seats are fully recharged and the bus is ready to go.
Another way this method of transportation is gaining energy is from braking. Also, in order to make them greener, the charge stations can be equipped with solar panels. Overall, the ultracapacitor buses uses 40 procent less energy than the conventional trolley bus. And also in the “battle” with the lithium-ion battery buses, the new technology wins, proving to be 40 procent cheaper.
But there is a downside to the ultracapacitor. It can only store 5 procent of the amount of energy, the lithium-ion battery is able to hold, but on the other hand they very rapidly charge and recharge. The ultracapacitors are made of activated carbon and posses an energy density of 6 Watts-hours per kg, when today’s top lithium-ion battery have the potential of 200 Watts-hours per kg. This is the sector where improvements need to be made. They already succeeded in getting twice the energy density of the existing ultracapacitors, but their goal is to expand it to 5 times the amount.
Another disadvantage of the current generation of ultracapacitor buses is that they lose 35 procent of their range when the air conditioning is turned on, from 5 miles to only 3. Nevertheless, they still could be implemented in more crowded cities, where bus stops are more closer to each other.
Tags: braking, bus stop, charge station, cheaper, demonstration, energy density, energy storage, Green Technology, greener, lithium-ion battery, solar panels, ultracapacitor bus