Zinc Air Fuel Cell

The idea for zinc/air batteries, or fuel cells, has been around for a long time, and in the last couple of years Electric Fuel, an Israeli company, has been getting a lot of press. More quietly, Metallic Power near San Diego has been developing a rapidly refuelable system with a wide range of applications, and is about to start publicizing its story. These notes are adapted from the company’s draft announcement materials.

The rapidly refuelable fuel cell is reliable power source that is quiet, safe to handle, emission-free, recyclable and cost effective – and “recharges” in five minutes.

The fuel cycle uses Zinc, as a completely recycled, clean, nontoxic, and non-flammable fuel. Inside the closed fuel cell, zinc pellets (1mm diameter) are combined with oxygen from the air, forming zinc oxide (a safe white powder used in skin creams and sunblock) and releasing large amounts of electricity. The reaction takes place in the presence of potassium hydroxide, the same liquid electrolyte found in alkaline disposable batteries. Water, used as a reactant in the process, is recycled automatically within the fuel cell.

Five-minute refueling: the Zinc pellets are pumped into the fuel cell with the liquid electrolyte from a vending-machine-sized zinc recycling/refueling unit. Simultaneously, zinc oxide is pumped through a hose from the fuel cell to the “vending unit” as a mixture with liquid electrolyte.

After refueling, the “vending” regeneration unit uses electricity to slowly convert the zinc oxide back into fresh zinc fuel pellets, and oxygen is released back into the air. ItÕs a completely closed-loop system, with nothing to add, nothing to discard, nothing wasted, and three times the energy efficiency of a gasoline engine.

Metallic Power has patents pending or in preparation for new air cathodes, electrolyte management, sealed replaceable refueling cartridges, regeneration equipment design and zinc fueling technology.

The big difference with Electric Fuel’s approach–that system involves a sizable facility to swap out the entire cell, which then must be shipped back to a factory to be completely rebuilt. The factory would be a multimillion $ installation, compared with a few $thousand for an on-site vending-machine sized unit. (Note that Electric Fuel did not get a go-ahead from the German post office after a much publicized demo, and is now emphasizing development of disposable cell-phone batteries.)

Specific energy output currently is at 160 watt hours/kg with a potential of 220 Wh/kg, compared to lead/acid at 35 Wh/kg and lithium-ion at 100 – 120 Wh/kg. Energy density is 200 watt hours/liter, much better than lead/acidÕs 75 Wh/liter. Recharge time for a lead/acid battery is eight hours compared to zinc/airÕs five minutes. Long term potential includes fuel cells for electric cars with a range of 300 miles.

Near term applications include: Industrial Non-Road Vehicles (e.g., maintenance carts and fork lifts), Turf Maintenance (e.g., golfcourse mowers); Motor Scooters (especially in Asia); and Commercial Back-up Power Sources (e.g., telecom and marine industry generators). Note the emphasis on small “fleet” style operations whose controlled environment can adapt most readily, and support an on-site vending/regeneration unit.

Current customers and partners include:

– Toro, manufacturer of turf maintenance equipment,to facilitate quieter morning and night-time mowing and less damage to golf course greens.

– Textron, manufacturer of Cushman and E-Z-GO small utility vehicles, to increase availability and decrease down time.

– U.S. Army, testing prototypes for silently powering electronic equipment in forward military positions.

– South Coast Air Quality Management District, supporting clean-air technology demonstration

– U.S. Dept of Transportation, supporting advanced transportation technology development

– ABB, to supply power electronics and product integration for backup power systems based on the company’s zinc/air fuel cells

The Zinc/Air Fuel Cell will reduce operational costs as compared with lead-acid battery powered equipment because instant refueling eliminates the need for duplicate equipment and batteries. Overall cost of ownership should be comparable to or lower than that of gasoline powered equipment.

The company demonstrated the world’s first zinc pellet powered vehicle in Sept 98. It was powered by a 2.2kW (3hp) unit and ran for several hours. An improved version at 4kW and 48 volts (an alpha prototype) will operate for at least 100 hours by Sept 99 together with the alpha prototype zinc regeneration unit.

Currently, the company is signing up customers for a beta prototype three month rental program for 48 volt units in the year 2000. Interested parties should make contact soon, because half of the 50 fuel cells in the program are already booked. Commercial production is anticipated in late 2001.

Metallic Power will begin raising a second round of equity funding in a few months, and a detailed business plan will be available to potential investors.

Jeff Colborn, Chairman & CEO
Metallic Power Inc., Carlsbad, CA, (near San Diego)
760-804-7600 x116 jeff.colborn@metallicpower.com

Company website (available in late March) http://www.metallicpower.com

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