FuelCellsWorks

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.

Bacteria that generate significant amounts of electricity could be used in microbial fuel cells to provide power in remote environments or to convert waste to electricity. Professor Derek Lovley from the University of Massachusetts, USA isolated bacteria with large numbers of tiny projections called pili which were more efficient at transferring electrons to generate power in fuel cells than bacteria with a smooth surface. The team’s findings were reported at the Society for General Microbiology’s meeting at Heriot-Watt University, Edinburgh, today (7 September). The researchers isolated a strain of Geobacter sulfurreducens which they called KN400 that grew prolifically on the graphite anodes of fuel cells. The bacteria formed a thick biofilm on the anode surface, which conducted electricity. The researchers found large quantities of pilin, a protein that makes the tiny fibres that conduct electricity through the sticky biofilm.

“The filaments form microscopic projections called pili that act as microbial nanowires,” said Professor Lovley, “using this bacterial strain in a fuel cell to generate electricity would greatly increase the cell’s power output.”

The pili on the bacteria’s surface seemed to be primarily for electrical conduction rather than to help them to attach to the anode; mutant forms without pili were still able to stay attached.

Microbial fuel cells can be used in monitoring devices in environments where it is difficult to replace batteries if they fail but to be successful they need to have an efficient and long-lasting source of power. Professor Lovley described how G. sulfurreducens strain KN400 might be used in sensors placed on the ocean floor to monitor migration of turtles.