Hydrogen-powered vehicles have zero harmful emissions; producing little emissions beyond water. In Brazil and around the world, fuel cell buses are having a renaissance.

Sau Paulo's motto has been "I am not led, I lead," so perhaps it is appropriate that the city will be receiving the first of several clean buses. The first bus will be driving through the streets of Sau Paulo, covering the ABD Metropolitan Corridor, between Sao Mateus and Jabaquara.

The bus uses an interesting hybrid system, combining hydrogen fuel cells with batteries, resulting in even higher efficiency. The batteries, for example, could be used to capture energy generated during stoplights, while the fuel cells (generating 68 kW) are designed specifically for automotive use.

Brazil also happens to be the world's largest bus market, producing more than 50,000 units a year. Sao Paulo also has the biggest bus fleet in the world, making motor vehicle emissions a threat to air quality.

The program means more than just a few buses coordinated between Brazilian transportation and energy agencies and funded by several global groups, including the United Nations Program for Development. International funding was due to the transit project being selected according to the country's emerging economy, which buses performing the vital task of ferrying commuters around the metropolitan area.

Some areas in Brazil have been heavily polluted-- Cubutao, one of the worst areas and once surrounded by mudslides caused by acid rain. 90 percent of air pollutants can be traced back to motor vehicles, especially with the use of diesel in most mass urban transportation.

The original Brazilian goal was four hydrogen buses by June 2010, after two months of testing earlier this month. Daimler has also continued work on the Mercedes Benz fuel cell bus.

New fuel cell buses are finding their way into a number of markets, in Canada and California, for example. The Hydrogen Bus Alliance was formed by several European countries, representing over 12,000 buses, and are working towards commercial viability, which they predict in the 2010 to 2015 time frame.

Brazilian legislation is making strides to correct local environmental issues and is now attacking one of the dominant contributors to pollution. At the same time, hydrogen is beginning to get some attention, though it does seem to come in waves.

Picture courtesy of the UNDP.