UNDER the Singapore Initiative in New Energy Technology (Sinergy), six Mercedes-Benz A-class fuel-cell cars arrived in 2004 to undergo testing in a tropical, urban environment.

F-Cell cars work by using a catalyst to combine hydrogen and oxygen to produce electricity, with only heat and water as by-products.

This so-called "zero-emission" process makes the cars very quiet, with the high-torque electric motor well-suited for urban driving.

The partnership between Daimler and BP, which supplied the fuel, came to an end in March when the latter decided to close its stations, citing the present non-viability of fuel-cell cars.

Daimler is currently searching for another partner to build more stations within the city for proper field testing to resume.

A lighter alternative

AT THE Smart Energy Mandai station, a Mercedes-Benz taxi is filled with compressed natural gas (CNG).

Prices, which are pegged to that of High Sulphur Fuel Oil (HSFO), have been steadily rising from $1.28 per kg in February to above $1.60 per kg on Nov 8.

Come next week, they are once again set to fall in tandem with HSFO prices, with Smart Energy publishing an advance price of $1.48 per kg for Nov 10 on its website.

About 2,700 out of 850,000 vehicles here are equipped to run on CNG, and some owners prefer to refill in Malaysia, where the price of gas, at 32 cents per kg, is one-fifth that in Singapore.

These articles were first published in The Straits Times on Nov 8, 2008.

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