11/03/2004 - Electric Vehicle Division Arotech Corporation has operated a successful prototype hybrid electric bus with fuel cells, zinc air , using commercially available zinc rather than the proprietary dendritic zinc heretofore required. This could raise the prospects for the hybrid bus market and zinc air now in its fourth phase, and final of its development agenda.
The hybrid electric bus 40 feet, use Arotech to fuel cells and zinc air, primary energy source, which combined with a pack of ultracapacitors recharged through regenerative braking energy by the unit, helping lift the end of acceleration. The bus, uses a General Electric 200hp motor, induction, liquid cooled, with a range of 133 miles in an urban drive cycle.
modules fuel cell Arotech zinc-air, containing 47 individual cells connected in series air suction. The bus carries three trays of 6 modules each, for a combined capacity of 312 aboard kWh of energy. Each cell
consists of a replaceable cassette fuel anodic zinc particles in a liquid solution of potassium hydroxide (KOH). The cassette is flanked on two sides by high power cathodes for oxygen reduction.
oxygen from the air reacts with the cathode to produce hydroxide ions. These in turn react with the zinc fuel inside the cell, producing zinc oxide and energy. The zinc fuel cell and air, on board, has an energy density of around 200 Wh / kg and an energy power of 90 W / kg at 80% depth of discharge, better energy density than other types, competitors, battery as shown in the table below, but weaker than most with regard specifically to the energy output.
energy density, for a vehicle, is a measure of how much energy can be stored per unit weight, and this affects performance. The energetic power to a vehicle, is a measure of the amount of energy released per unit weight, and this affects the acceleration. For example: high energy density and high energy to deliver a long-range performance and great performance. A high energy density and low energy power provide a long performance, but an acceleration slow. Comparatively: Gasoline has an energy density of approximately 13,000 Wh / kg (13 kWh / kg).
Consortium for Advanced Battery NA U.S.. (USABC, whose members are: The Detroit Big Three, the Research Institute of Electric Power, battery manufacturers and the DOE), established to develop batteries for the next generation electric vehicles, have established performance goals long performance of EV batteries, they are an energy density of 200 Wh / kg and an energy power of 400 W / kg.
To compensate for the lower energy density, Arotech used The hybrid design to improve acceleration with the use of ultracapacitors.
HEV Battery Types Battery
energy density
Power Energy (Wh / kg) (W / kg) Lead-Acid
a 3575-130 25
Advanced Lead-Acid 35 a 42240-412-nickel hydride
Metal (NiMH) 50 to
Nickel 80150-250-(NiCd) 35-5750 at 200
Lithium-Ion (Li-Ion) 100-150300 56-70100
Zinc-Bromide Li-Polymer 155100-315 100 a 90100 NaNiCl
Zinc-Air 110-200100-Aire Zinc
of Arotech 200 90
Vanadium Redox 50110 sel
long-term goal of 200 400
USABC Instead of recharging depleted cells Zinc Air fuel on board, spent modules are exchanged for new ones. The depleted cassettes are electrochemically recharged in special places of regeneration, using electricity, is mechanically recycled and returned to use.
Arotech is also involved in a German research project to develop a hybrid vehicle batteries using zinc and air as the primary energy source. The vehicle design is based on a van load of Daimler Chrysler and will also use high-energy Varta batteries and ultracapacitors under development by Dornier GmbH and COPD AG.
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