In addition to the losses inherent in current diesel engine design, tractor/trailers have other inefficiencies that Gemini intends to address.  These include:

1.    Parasitic losses in engine output due to auxiliary drives for cooling fans, alternators, etc.
2.    Energy losses in the transmission, particularly as the industry converts to more automatic transmissions 
     due to a shortage of skilled drivers
3.    Similar energy losses in the differential and other drive train components
4.    Waste heat given off during braking
5.    Aerodynamic inefficiency of the current, modular tractor/trailer designs.
6.    Limited use of modern, weight saving materials.

Gemini Engineering Technologies feels that these are additional areas where our ideas and expertise can have a significant impact. 

Electric hybridization is the paradigm embraced by most companies attempting to make class 8 trucks more efficient.  Our designs leverage the time-tested technologies of hydraulics, co-generation, reformation, gasification, and aerodynamic packaging.
Source: Technology Roadmap for the 21st Century Truck Program - A Government-Industry Research Partnership, U.S. Department of Energy, December, 2000

Current truck and trailer packages are plagued by significant aerodynamic deficiencies that are in large part perpetuated by an industry unwilling or unable to stretch beyond the bonds of convention.  Freightliner, a division of Daimler/Chrysler, recently announced their new Cascadia tractor as “the industry's most aerodynamic truck.”  Their press release at its introduction touted that: “The Cascadia offers a 3 percent improvement in fuel economy over previous models. To achieve this, more than one million engineering hours, including 2,500 hours in Freightliner’s state-of-the-art full scale wind tunnel, went into its development.” [1]

As can be seen in the diagram above, a conventional semi-tractor/trailer may lose as much as 25% efficiency due to drive train and aerodynamic inefficiencies.  UPS, the U.S. Environmental Protection Agency, Eaton Corp., International Truck and Engine, and the U.S. Army have been working with hybrid hydraulic drive systems for delivery trucks that have shown fuel savings of as much as 70%[2].  The systems eliminate a conventional transmission and drive train, substituting hydraulic pump/motors instead.  The pump/motors reclaim energy normally lost when braking in a conventional truck, reusing that energy, along with that provided by the engine, to propel the truck. 
Source: Taking on the Leadership Challenge in Class 8 Trucking - How To Double Class 8 Truck Efficiency — Profitably, Rocky Mountain Institute, 22 February, 2005

Gemini has taken the hydraulic drive concept and adapted it specifically for long haul tractor/trailers.  Instead of a conventional transmission and drive axle, our trucks will be powered by hydraulic motors mounted in the drive wheels.  These motors are in common use in industrial and other applications throughout the world.  In our system, instead of driving a transmission, the diesel engines will drive hydraulic pumps.  The pressurized hydraulic fluid will be pumped to the individual wheels to drive the tractor.  During breaking, the hydraulic motors will become pumps, enabling energy normally lost as waste heat to be stored and recycled to drive the tractor again.  Similar, but simpler hydraulic motors will be used as brakes in the trailers, enabling us to recycle even more of the energy that is currently wasted as heat.

Another key element of our approach incorporates dual engines.  The use of a hydraulic drive makes the dual engine concept both feasible and practical.  With a hybrid automobile, either the gasoline engine or the electric motor is the primary mover of the car.  When additional power is needed for passing or accelerating from a stop, the other power source kicks in for a short period.  Our drive will use the same principle, but with two efficient diesel engines.  While cruising, or in light load or low speed operation, only one engine will be running.  When accelerating or climbing a grade, the second engine will automatically power on.  This allows the lead engine to operate more often in its optimal load range, where it runs the most efficiently.  The tractor will be fully capable of operating with only one engine, so reliability will increase.  An electronic controller will alternate each engine as the primary or auxiliary, so maintenance and wear will be equalized.

While this may seem like expensive redundancy, there is one more, very significant advantage to our dual drive system: Using two, smaller engines and eliminating the center transmission and differential allows us to configure the center of the tractor to carefully channel air flow through the center of the tractor and beneath the trailer.  This means that less air needs to be pushed out of the way by the front of the tractor.  The “channeled” air is then used to minimize turbulence around the trailer, reducing aerodynamic drag, and is then channeled out behind the trailer.  The way in which the air exits is designed to fill the void left behind the trailer as is passes through the air, giving us a very significant improvement in the coefficient of drag (C_D).

Our transportation package includes breakthrough technology that will radically change the face of the trucking industry--without significantly changing to the overall dimensions of the vehicle.  While large manufacturers struggle to achieve two or three percent reductions in aerodynamic drag, as noted earlier, and the federal government targeted a 20% reduction[3], our model has already shown a forty-five percent reduction.  At highway speeds, this translates into a savings of sixty-five to seventy-five horsepower.