Five buses with hydrogen fuel cells will be put to the test in 2007 in Sao Paulo and neighbouring cities. The four-year experiment calls for total travel of one million kilometres. If they pass the test, the hydrogen bus fleet will be expanded to 100 or 200.

A similar project will get under way next year in Rio de Janeiro.

Hydrogen allows the manufacture of quieter-running and more long-lasting vehicles, and is an attractive alternative when faced with the skyrocketing prices of oil and the need to protect the environment.

Hydrogen represents "a jump in efficiency of 20 to 30 percent with respect to the existing combustion engines, which are inefficient and only use one third of the energy generated by liquid fuels," Jayme Buarque de Hollanda, director general of the National Institute of Energy Efficiency (INEE), explained to Tierramérica.

One source of hydrogen is production through the electrolysis of water, of natural gas, or of alcohol.

The hydrogen bus project in Sao Paulo, which has the backing of the United Nations Development Programme (UNDP), opted for electrolysis, the most simple and readily available technology.

The problem is the initial investment. "The prototype of these vehicles costs 10 times the price of a diesel bus," says Marcio Schettino, coordinator of the project, developed by a partnership between the Sao Paulo Metropolitan Urban Transportation Agency and the Ministry of Mines and Energy.

"Another 15 years will be needed before this technology is competitive with other vehicles," he admitted in a Tierraméric interview.

Making hydrogen economically viable requires time. "Its production (whether from water, gas or alcohol) is still very costly. Furthermore, there are problems with transport and storage, because hydrogen is flammable and volatile," says Antonio Nunes Junior, president of the Brazilian Association of Electric Vehicles, ABVE.

At the Federal University of Rio de Janeiro, a project in consortium with several companies -- the state-owned oil company Petrobras, several bus manufacturers, and scientific institutions -- will produce hydrogen from natural gas too supply a bus that is also slated to begin circulation next year, near the university.

The objective of that project is "to develop the technology and research," distinguishing it from the otherwise similar effort in Sao Paulo, focused on testing the buses in practice, said Nunes.

According to Hollanda, in Brazil there would not be any great difficulty to supply electricity for electrolysis, but also promising is obtaining hydrogen from ethanol, which is already produced in massive quantities in this country, has high energy efficiency and important environmental advantages.

"Clean energy doesn't exist," given that all sources produce some sort of waste, although in different quantities in of different types, says Hollanda, qualifying the arguments that praise hydrogen as a "zero pollution" energy source.

"What we have to do is seek one that least affects the environment and the most appropriate solution for each place," he adds.

For now, faced with the uncertainty surrounding hydrogen energy, Brazil is staking its bets on hybrid electric vehicles.

This technology, used in 43 buses already serving the Sao Paulo metropolitan area, combines electrical generation from fuel, and batteries that accumulate the energy not consumed at certain moments of travel, and making use of it in others, when a boost is needed, such as driving uphill.

The hybrids are a good transition option, "because the outlook for hydrogen isn't clear," said Nunes. They can use diesel, gasoline, natural gas or ethanol, maintaining its environmental advantages and saving fuel, as well as having a longer life on the road. An electric motor can travel 1.5 million km, while conventional ones begin to present problems at a distance 10 times less, he added.

But hybrid buses cost 30 to 40 percent more than those that run on diesel, Nunes acknowledged. That cost for acquisition could be compensated in the long run, saving fuel, brakes and other components, especially with government incentives.

Stricter environmental regulations, as are being implemented in some parts of the United States, as well as government policies for public transportation, could stimulate change in the transport technology base, he said. Once a certain scale is achieved, which would drive down the costs of hybrids, that option could become competitive, overcoming the limitations of the market.

(* Mario Osava is an IPS correspondent. Originally published Aug. 19 by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme and the United Nations Environment Programme.)