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The combination of hydrocarbon fueled and electric traction driven machinery has been around for over a decade. These drives are popularly known as hybrid drives. It has proven itself as the most fuel conserving, tried and tested prime mover for all types of automobiles. Personal and commercial hybrid motor vehicle sale is increasing by leaps and bounds over the years. The time is not far away when hybrid vehicles will overtake the traditional automobiles in sales across the world.
Alongside surely and swiftly it is proving itself in various other applications in transport and transport related sectors; as the most fuel-efficient prime mover. Hybrid drives have clearly demonstrated their need for lesser quantum of liquid or gas as fuel; particularly where idling, short runs and waiting and a number of stops and starts is part of the operative norms, in cargo and passenger traffic where this is common.
Hybrid diesel-electric combination (Coupled with diesel engine and electric motor) has started encroaching the suburban bus transportation vehicle market in USA. Studies have indicated a savings in specific diesel fuel consumption by over 25 percent. Needless to say that exhaust emission and air pollution has considerably reduced; an important gain! Another significant advantage is the greatly reduced cost of maintenance and spares, because for the same mileage covered, diesel engine running hours at high loads is significantly reduced, while the traction electric motor takes the total traction load. This has been a positive factor for considering hybrid buses over conventional ones.
For shunting locomotives where service criteria demands longer idling periods and frequent start and stops and short runs while wagons are coupled or decoupled, the hybrid locomotive is a big fuel saver compared to traditional straight diesel shunting locomotives. Fuel records of hybrid shunting locomotive operations in USA and Canada have shown more than 40 percent savings in diesel fuel consumption for hybrid locomotives.
FedEx, one of the largest road cargo haulers in USA is introducing a hundred hybrid engined delivery trucks. Their feasibility studies have projected more than 50 percent savings in fuel consumption and maintenance, with the added bonus of big improvements in exhaust gas emissions; an important factor in many states in USA.
The next area of service where hybrid drive will prove itself is tug-boat operation, where service criteria is very similar to a shunting locomotive. For this operation in restricted waterways and crowded ports and harbors; hybrid tug-boats could well save over 30 percent in diesel fuel consumption.
Plug-in hybrids, operating in daylight hours and with battery charging overnight is a proven popular choice for school-bus service. It is estimated that for an average bus route the savings in diesel fuel is around 50 percent. Higher price for hybrid bus compared to a traditional diesel bus is the only drawback for rapid changeover to hybrid school buses.
The construction sector awaits the hybrid encroachment. A new type of hybrid excavator is coming into the market. The nature of excavator operation is ideal for hybrid drive. The hybrid excavator shows remarkable fuel economy because of frequent start and stops for travel, frequent idling of drives while bucket is lifted and lowered and tilted over dump trucks. In the next few years self driven cranes and excavators and even trailers, tractors and dump trucks can all benefit from hybrid drives with sizeable savings in diesel fuel consumption. Prototype models have already been demonstrated in a number of equipment fairs in USA.
If this is the USA scenario; possibly the largest importer of petroleum products, yet with no mean unexploited local reserves; the issue is where do we stand? We import every drop of petroleum fuel; and must (repeat must) go all out for liquid petroleum fuel conservation today! What has been written earlier for petro-electric or diesel-electric hybrid drives, is also applicable for gas-electric hybrid drives. We can not only save petroleum fuel; but gain the added bonus of improving air pollution at one go; if we go all out for hybrid drives for road transport vehicles. It will be the proverbial " killing of two birds with one stone!"
The key issue is government commitment, backed with sound management decisions and matched financial incentives and penalties to move us out of the traditional petrol and diesel engines for all our transport vehicles of cars, buses, trucks and all forms of road vehicles, The combination of direct savings in lesser fuel consumption and lower spares and maintenance needs, will clearly indicate a cost benefit advantage within the next few years. It all points to the undeniable need for going for hybrid driven engines for all our road vehicles; at the earliest.
S.A. Mansoor, Technical Adviser, Spectra Group, Dhaka
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