HOW ARE VEHICLES POWERED BY ULTRACAPACITOR?

Energy stored in ultracapacitors is far below that that stored in a battery. However, it has enormous advantage of quick charging in minutes, as against hours taken by a battery. While ultracapacitors have been used for several supplementary functions in vehicles, researchers had been trying to use them to as main energy source where a smaller storage capacity may be permissible. Ultracapacitors today run vehicles of various types- from golf carts, mini buses, buses, as also trams and metro trains, and few car models have been designed to run on ultracapacitors. Heavy vehicles also have the option of ultracapacitor plus battery combination for long distance travel between cities.

Golf Carts

Ultracapacitors work well on golf carts, as modules can be charged at convenience, and offer very long life. Life of these modules, over 20 years, is far better than any battery, and they are quite economical to run. They are ideal for short-term, high-power demands on uneven and hilly surfaces. Nominal voltages of modules vary from 12V to 72 V, with energy ratings from 3 kWh to 8.5 kWh. They work well in all weather conditions and low or high atmospheric temperatures do not cause any drop in performance.

Minibus

Minibuses at airports, malls, shuttles and those in large campuses are ideal for ultracapacitor application. They get the benefit of high power, long life, and convenience charging in minutes. Ultracapacitors are most suitable due to frequent starts and stops and ideal for short distances needed for these buses. They consume up to 40% less electrical energy compared to battery, or 80% lower than diesel buses in operational costs.

Racing cars

Most racing cars today use hybrid vehicles with ultracapacitor power, replacing batteries altogether. Toyota introduced model TS030 in 2012 with power train consisting of ultracapacitor + IC engine combination. Its rear motor was 225 kW (300 HP). Front motor was used for regeneration braking and charging of ultracapacitor modules. Total power available was 830 BHP.

The car starts with ultracapacitor power with high acceleration, and IC engine starts only when the car has achieved near full speed.  Ultracapacitors are recharged by IC engine while running. IC engine size is thus drastically reduced, lowering weight of vehicle, making optimum use of engine capacity. IC engine and ultracapacitor capacities can be combines as needed when running.

Hybrid cars

Number of hybrid cars have replaced batteries with ultracapacitors. For example, Lamborghini Sian FKP37 uses IC engine plus ultracapacitors as power source. Ultracapacitor power, with 2.4 kW/Kg at 48 V, runs its 25kW electric motor Maximum operating current is as high as 600 A. At a power 34 CV, the module enables a torque of 25 Nm. With maximum speed over 350 km/h, the vehicle reaches 0-100 km/h within 2.8 seconds. Ultracapacitors and IC engines can be combined when needed to get maximum power of 602 KW.

Forklifts

Forklifts used in godowns and industry, powered by batteries, with particularly onerous duty, have serious issues with batteries. These get discharged in very short time, needing replacement in a couple of hours, midway in a shift. Batteries have to be replaced and sent for recharging frequently, causing a loss of time, and also requiring number of spare standby batteries. Operations involve loss of labour, time and money. Battery life is reduced drastically because of frequent heavy discharges, and separate space has to be designated for battery charging.

Ultracapacitors were first introduced in parallel with battery, which almost eliminated battery overloads and downtimes, with huge saving in time, costs and charging space. Next development was to develop forklifts powered by ultracapacitors alone.

The modules allow forklifts to work non-stop throughout the day, with charging in minutes at convenience wherever and wherever possible. Modules give large busts of power during forklift operation effortlessly. There is huge benefit of regeneration when lowering of materials by lift, saving substantial amount of energy. Further, the modules offer good reliability in all weather conditions. Ultracapacitor modules completely eliminate the charging area needed for batteries, saving valuable space.  The modules need no maintenance and have long life of over 50,000 charge / discharge operations, or over two decades.

Ultracapacitor buses

First trials were made in Russia, and a bus was developed in 1995 to run on a 15-minute route. China introduced Capabus in 2004 in Shanghai, which could run 5 km once fully charged, and could be charged en route at ‘umbrella stops’, from an overhead structure within 30 seconds, by the time passengers boarded and deboarded.

Today, with the development of energy dense ultracapacitors, range of buses has gone as high at 40 km per charge. Ningbo, China has world’s fastest charging ultracapacitor buses, which get charges in just 10 seconds en route, on 11 km route with 24 stops. Regeneration systems recover 80% of energy during braking. Bulgaria, Belgium and few other countries have introduced ultracapacitor powered buses.

Long range buses for intercity travel often use ultracapacitor and battery combination, utilizing advantages of both, with high efficiency and long range.

Rail applications

Ultracapacitors are increasingly used in rail vehicles to provide fast energy storage and delivery for acceleration, regenerative braking, and bridging power gaps where overhead lines are not available or impractical.

In hazardous mining environments, overhead lines are not permissible, and batteries and IC engines can be dangerous. Ultracapacitors provide on-board energy storage, and can be charged over ground in short time. Braking energy is harvested, improving energy efficiency while ensuring safety. Operational costs are lower.

In 2016, China introduced trams fully powered by ultracapacitors.  Energy storage module of 9500 F can be charged in 30 seconds. Vehicle has a range of 3-5 km per charge, with running speed of 70 km/h.  Energy as high as 85% is recovered during deceleration and braking. Charging systems working at 900 V, are located at stations. Similar trams are operating in some countries today.

E-Rickshaws with ultracapacitors

Rick-E in U.S.A. has introduced e-rickshaw powered by ultracapacitor with capacity of 8 kWh, and a range of 120-150 km with 4 passengers. Battery of ultracapacitor has a high energy density of 100 Wh/Kg, and is expected to last over 45 years. Vehicle speed is rated at 60 km/h with full load.

Adarin Engineering, Bangalore has developed similar e-rickshaw with 70 km range, and running cost as low as Rs. 1.5/Km. Charging time of this vehicle is just 5 minutes.

There are many more applications of ultracapacitors as main or supplementary source of power in vehicles. Hydrogen vehicles always need a storage device, where ultracapacitors can fit in nicely. Two-weelers are being designed with ultracapacitors as replacement of battery or as supplement for start-stop operations.