0.4 Hydrogen and fuel cells  (Page 13/4)

Hydrogen and fuel cells experiment

Objective

• Build a fuel cell in order to appreciate practically a range of important chemical and physical principles, such as galvanic cells, energy conversion, energy quality, combustion reactions, water electrolysis and bio-fuels.
• Crituique the design in order to improve the efficiency of the fuel cell and to accomplish it practically

Grading

• Pre-lab (10%)
• Lab Report (80%)
• TA points (10%)

Before coming to lab…

• Read the lab instructions

Introduction

As the world’s reserves of fossil fuels are diminishing and our awareness of environmental protection is increasing, we strive to develop alternative ways of energy production. Thus in many countries research into construction of stable and efficient fuel cells has been given high priority. Indeed, President Bush in his January 28th 2003 State of the Union address, proposed a $1.2 billion fuel-cell research and development program.

Fuel cells are used for direction conversion of the energy of combustion reactions to electrical energy. A possible fuel is hydrogen, which can be produced from water in electrolysis plants driven by solar cells or windmills. A future interesting fuel source for operation fuel cells might be “bio-fuels” i.e fuels produced from non-fossil organic material such as methane from biogas plants, alcohol produced by fermentation of sugar or hydrolyzed starch (or, in the not so distant future, perhaps also from enzymatically hydrolyzed cellulose).

Conventional power plants turn approximately 40% of the fuel energy into electricity; we say that the efficiency of the plant is 40%. (Although, in some modern plants surplus heat is reused for district heating thus increasing the actually efficiency somewhat). However, with fuel cells the efficiency of chemical-to-electric energy conversion is unsurpassed, namely about 70% (or even high in some experimental plants).

U.S. energy dependence is higher today than it was during the “oil shock” of the 1970’s, and oil imports are project to increase. Passenger vehicles alone consume 6 million barrels of oil every day, equivalent 85% of oil imports.

• If just 20% of cars used fuel cells, we could cut oil imports by 1.5 million barrels a day.
• If every new vehicle sold in the U.S. next year was equipped with a 60kW fuel cell, we would double the amount of the country’s available electricity supply.
• 10,000 fuel cell vehicles running on non-petroleum feul would reduce oil consumption by 6.98 million gallons per year.

Fuel cells could dramatically reduce urban air pollution, decrease oil imports, reduce the trade deficit and produce American jobs. The U.S. Department of Energy projects that if a mere 10% of automobiles nationwide were powered by fuel cells, regulated air pollutants would be cut by one million tons per year and 60 million tons of the greenhouse gas carbon dioxide would be eliminated. DOE projects that the same number of feel cell cars would cut oil imports by 800,000 barrels a day – about 13% of total imports. Since fuel cells run on hydrogen derived from a renewable source, the fuel cell emissions will be nothing but water vapor.