REGENERATIVE PADDLE-WHEEL BOAT
The electric or hybrid regenerative paddle-wheel boat or RPB, is an economic and ecological solution for the people locomotion, fishing, and merchandise transport on rivers, which will have none (if electric) or reduced (if hybrid) fuel consumption and CO2 emissions, in comparison to the usual engine/propeller driven boats.
The electric RPB uses for propulsion one or more than one system formed by a battery pack electrically connected through an electric/electronic control unit or ECU to a motor/generator, which in turn is connected to paddle-wheels by a belt or chain transmission device.
The hybrid RPB has in addition, one or more than one system comprising a fuel tank, and an internal combustion engine driving either a propeller or an additional electric generator to charge the batteries.
When the RPB is anchored or moored, the paddle-wheels can then be used to harvest hydraulic energy from the river flowing waters to move the motor/generator, and regeneratively charge the battery packs, what precludes the RPB operation in lakes and seas.
Switching between propulsion and battery charging modes will be carried by the ECU that will also provide: A drifting navigation mode with locked motors and paddle wheels. A gliding navigation mode, with free motors* and “wind milling” paddle-wheels, especially useful for hybrids when their batteries are empty.
A Plug-in and out mode for electric connection with external networks.
The RPB propulsion components are of current technologies and can be supplied by the boat and automotive O&M industry. An exception is the paddle-wheel that superseded by the propeller higher propulsion efficiency is no longer in production, but it will offer no problem to design and fabricate**
The reason to use paddle wheels instead of propellers is that in order to harvest power from the typically river water low speeds, even ducted variable pitch propellers would need to have too large diameters what would compromise operation in river shallow waters.
The initial RPB prices could be higher than that of equivalent engine/propeller boats but its zero (if electric) or lower (if hybrid) fuel consumption and its lower electrical component maintenance costs, will lead to a rapid amortization of this difference that may be smaller with the use of MEH batteries, heavier but cheaper and more rugged in the humid river ambient than Lithium batteries.
The RPB use will improve navigation safety, due to the electrical components high reliability, and due to its predominant daylight operation with the battery charging moored or anchored periods done, whenever possible, at night. The electric RPB will also contribute to reduce noise pollution.
Figure 1 shows a perspective view of a moored central wheeler RPB charging batteries and three possible electric RPB configurations.
Figure 2 shows two possible hybrid RPB configurations, and also that of a self-propelled electric barge to be used as power supply at low accessible river banks.
* Unlike mechanical engines the electric motors have negligible torque when idle.
** i. e.: Using composite materials.