Zinc-air battery challenges conventional rivals

A rechargeable zinc-air battery from Germany designed for the "mobility" market - including small indoor forklifts - offers a longer service life than conventional lead-acid batteries, according to its developers, ZOXY Energy Systems.

The ZOXY cell's fuel source is a highly porous, elementary zinc anode, made from mechanically compressed zinc sponge that releases zinc ions.

Oxygen enters the cell and once inside the cathode, reacts with the incoming electrons and the water from the potassium hydroxide solution used as an electrolyte. The zinc ions and the hydrogen ions combine to produce zinc hyroxide, generating an electric current.

When the ZOXY zinc-air cell is charged, the oxygen absorbed during discharge is released again and the zinc oxide is deposited again as metallic zinc at the anode.

This increases the battery lifespan, reduces costs and extends the range of uses, ZOXY says.

The energy density of its zinc-air unit is up to 300-watt-hours per kilogram of battery weight and is about 10 times higher than that of lead-acid alternatives, and "distinctly greater than that of lithium batteries", the company says.

The zinc-air combination, rather than lead, cadmium or other heavy metals, also allows ZOXY's products to be marketed as better environment choices.


Europeans unite to ride fuel-cell juggernaut

Fuel Cell Europe (FCEu) was formed in 1989 out of a concern that the EU might not be ready for the forthcoming commercial introduction of fuel cells - a new technology being driven by the US and Japan.

At its Lucerne conference in July 2001, a number of leading players in the industry, known as the "ad hoc group", concluded that employment and competitiveness in Europe could be endangered, and environmental and economic benefits could be delayed.

Unless the situation was corrected, the group added, Europe might not participate fully in a new, innovative and dynamic global industry.

With economically viable fuel cells expected to be available after 2005-2006, the group came to the conclusion that levels of political support and awareness differed considerably across Europe.

The group decided the European Commission and key national governments lacked direction in funding and policy support and European industry associations were not addressing these issues adequately.

Furthermore they concluded, the really critical players - industry leaders - were not effective enough in influencing policy and the regulatory framework. Codes, standards and permitting procedures were inappropriate and an entirely new proactive and coordinated approach was required to deal with public institutions, key opinion formers and regulatory authorities.

The FCEu has about 40 member organisations and affiliates, including such names such as Dupont, Celanese (formerly Hoechst), Daimler-Chrysler, Engelhard Metals, German utility EWE, Chevron Texaco Technology Ventures and Core Technologies.


Electric and IC forklifts now on 'level playing field'

The latest lead-acid battery technology has leveled the playing field for electric and internal combustion (IC) lift trucks, according to leading US industrial battery manufacturer EnerSys.

The company claims today's battery-truck combinations "under most circumstances" equal IC units in run speed, lifting capacity and incline or ramp speed and climability. This is because the latest batteries and chargers offer:

* Up to 29 improvement in watt-hours/pound in the same size battery, because of technological advances since 1980
* Sufficient energy to complete a full shift without changing batteries
* Superior battery designs and low-resistance battery construction
* Fully automatic "smart" microprocessor electronics that increase AC-to-DC power conversion efficiency and thus use less electricity per charge. (By tailoring each charge to the preceding discharge, these chargers extend battery watering intervals and reduce battery maintenance. They also reduce the chance of human error in battery charging because special equalising charges can be carried out automatically, with no human intervention.)
* Low-maintenance flooded units that require watering as infrequently as four times per year for standard single shift operations. (Also, batteries designed for fast charging can accept much higher charge rates without damaging the battery from the additional heat created by the higher current flow. These batteries are designed to not only increase charge acceptance, but to manage heat as well.)


Forklift batteries 'lower costs'

EnerSys also asserts that while electric forklifts easily meet mandated workplace health and safety standards, as well as other anti-pollution and noise abatement criteria, they offer quite distinct advantages over any form of IC lift truck, including:

* Reduced maintenance for electric trucks, compared to IC trucks, means less downtime for electric vehicles. (This could translate into fewer vehicles and less capital cost for a given facility or operation.)
* Longer service life for electric lift trucks. (About 30 per cent longer than IC units, according to the Lead Industries Association.)
* Easier OSHA and anti-pollution requirements. (Usually no cost for plant ventilation and air purification with electrics. Safe, efficient operation in hazardous and controlled environments.)
* Lower fuel costs than for IC units because electricity costs less per hour of work. (Costs for battery power are lower even when factoring in the replacement costs of batteries as an energy outlay.)
* Overall lower operating costs. (National Services Inc, a consulting firm in Huntington Beach, CA, specialising in the economic control of material handling equipment, has accumulated a database of over 150,000 lift trucks to monitor the costs associated with internal combustion and electric powered units. On average, there is a difference in costs of $0.99 per operating hour, hence operating a truck for 10,000 hours would cost USD9900 more for the IC model. Based on a 4,000-lb (1812 kg) model, a propane unit operates at USD3.83 per metred hour while the comparable electric unit operates at USD2.84 per metered hour. When looking specifically at the average fuel cost per hour of operation, the cost of electricity is at least half that of gasoline, LPG or diesel - even when factoring in a "worst case" 50 per cent efficiency rating for the battery/charger combination.)


Checklist for charging

Proper charging practices are important in realising the maximum life of a battery.
EnerSys recommends the following conventional protocols:
* Use a charger with a constant current, constant voltage and a constant current charging method. (This method is designed to fully charge the battery without danger of overcharging and subsequent damage.)
* The charging method should keep the end-of-charge temperature below 110 degrees F (43.3 degrees C).
* Every effort should be made to ensure that the battery receives the proper amount of charge. (Consistent undercharge and/or excessive overcharge will contribute to internal battery problems with a loss of capacity and reduction of life.)
* Residual sulfation remains in the plates if the battery is not fully charged to name-plate specific gravity, or allowed to remain partially discharged for an extended period of time. (This results in reduced performance and life. All motive power batteries need to be recharged at least once every 48 hours to avoid sulfation.)
* Stratification caused by insufficient gassing at the end of charge. (Results from little or no mixing of electrolyte at the bottom of the cell compared to the top. This will eventually lead to sulfation of the bottom of the negative plate with subsequent fall-off in performance and capacity.)
* Excessive gassing, high battery temperatures and wasted power all result form excessive overcharging.
* Batteries should be brought to a state of full charge at least once a week in order to avoid excess sulfation, but appreciable overcharging must be avoided.
Given proper battery charging and maintenance, an industrial battery should provide 250 to 300 cycles per year (one full charge and one full discharge).
Most full battery warranties run from three to five years.