This is the VOA Special English Development Report.

A hydrogen fuel cell powered bus in Hartford, Connecticut, in 2007

If you travel by bus in Sao Paulo, Brazil these days your vehicle may be powered by hydrogen fuel cells. The city's urban transportation system recently launched the first of up to five hydrogen buses. The hydrogen reacts with oxygen to produce electricity and water.

The bus uses a hybrid system that combines the hydrogen fuel cells with high power batteries. It can be driven three hundred kilometers on the hydrogen cell and an additional fifty kilometers on its batteries.

The bus carries passengers in communities around Sao Paulo. The United Nations Development Program, the World Bank and other private, public and international groups supported the project.

Project official Carlos Zundt says the bus is the first of its kind in Latin America. Mister Zundt says the vehicle releases only water vapor and is "totally clean." Traditional buses that run on diesel fuel release harmful carbon dioxide and other pollutants. Most buses around the world run on diesel fuel. Mister Zundt says diesel vehicles are the main cause of air pollution in Sao Paulo.

The cost of the bus has not been announced. Hydrogen fuel cell buses cost more than traditional buses. But Mister Zundt says reducing air pollution and acid rain will reduce respiratory illnesses for people in the city. In addition, the new bus is very quiet and does not produce noise pollution. Mister Zundt says a hydrogen bus will last an average of twenty years, while a diesel bus can be used for five to eight years.

Sao Paulo has almost twenty million people. Almost half of them ride buses every day. Brazil has a large, modern and competitive bus industry. It is one of the top producers in the world. The project hopes to export hydrogen fuel cell buses in the future.

A Brazilian report says that Brazil is one of five countries that have developed such buses. The others are the United States, China, Germany and Japan.

But not everyone sees the hydrogen fuel cell bus as the hope of the future. Critics note the high cost of producing hydrogen. And they say other kinds of energy choices can provide power for buses.

And that's the VOA Special English Development Report, written by Jerilyn Watson. Transcripts and podcasts of our reports are at voaspecialenglish.com.