Hamburg  - Will millions of electric eco-cars one day solve our climate and energy problems? If batteries are charged with renewable wind and solar energy, electric cars are currently the cleanest on the road. But most batteries are made of lithium, a finite and expensive natural resource, which prompts sceptics to question the ambitious plans of many car makers.

Some analysts are already sounding warnings that the latest lithium-ion battery technology will at best occupy a small niche market. Lithium is a limited natural resource with most deposits in Bolivia, Chile and some in Australia and Tibet.

A strategy expert at the Paris ESCP-EAP campus, Professor Frederic Frery, points out that even if the current total lithium production of 25,000 tonnes annually is used for electric car batteries, this would only suffice for 1 million of the 50 million new cars sold annually.

"If all the lithium were used for electric cars the resource would only be enough to last for 10 years," he warns.

Lithium is a lightweight metal with a high energy density that has long been used for laptop and mobile phone batteries. Tesla and other manufacturers of electric cars are also using the metal for the manufacture of lithium-ion batteries that take up less space, weigh less and extend the range of electric vehicles.

Bolivia, one of the poorest Latin American countries, has the world's largest deposits of lithium carbonate in the Uyuni salt lake region. Bolivian President Evo Morales wants state-control of what is considered potentially "white gold". The price of lithium has more than doubled in the past five years as demand increases.

Nevertheless, several car makers and governments have ambitious electric car plans. BMW is currently leasing a fleet of 500 electric MINIs with a lithium-ion battery pack positioned in the space normally occupied by the rear seat. The cars have a range of 240 kilometres.

The United States government has earmarked 2 billion dollars for investment in hybrid and electric car technology.

Germany is earmarking 500 million euros for electric vehicles and their supply with energy. General Motors is planning to mass-produce its Volt electric vehicle in 2010. The Japanese Automotive Energy Supply Corporation is spending 1.1 billion dollars on lithium production facilities for use in electric vehicles.

Mitsubishi, like other Japanese manufacturers are planning electric cars, and has done its own research on the lithium supply and demand situation. It believes there will be an oversupply until the year 2013. Nissan is also upbeat about electric and hybrid vehicles aiming for a production of up to 200,000 units by the year 2011.

Others are more cautious. The head of Germany's automobile federation (VDA) Matthias Wissmann says the electric car will be driven mainly by a small group of eco-conscious motorists around 2014/2015.

Proponents of the lithium-ion battery technology point out that unlike oil, lithium can be recycled and that the expense is caused by the low production of the batteries and not by the high price of the metal itself. As demand increases, so the argument, prices for electric cars will drop.

There are also alternatives to lithium-ion batteries with Toyota's current Prius hybrid cars still running on NiMH or nickel-metal hybrid battery packs. As battery technology develops and demand for the new technology increases, optimists believe engineers will develop improved, affordable batteries and offer a longer range and shorter loading time. (dpa)