Amorphous PV used to Generate Hydrogen for a Fuel Cell Car

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Amorphous PV used to Generate Hydrogen for a Fuel
Cell Car

• Renewable Energy
• April 27, 2000
• Peggy Kaluzny

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Introduction

• Fuel Cell technology is improving
• Power density is increasing
• Packaging ability in cars is improving
• Problem is refueling!
• Reforming fuel on board is costly and can poison
  FC if not done well.
• Society is built around a gasoline infrastructure
  and a hydrogen economy is ideal for FCs
• What is the solution??

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Here is a suggestion

• Put the fueling station in the home!
• Use PV cells on roof to produce electricity to
  electrolyze water to generate the hydrogen fuel
  for the car.
• Location Detroit, MI Motor City

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System Schematic
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PV Cells

• United Solar Systems
• Amorphous PV Shingles
• Rated wattage 17 W
• Rated area 3 ft2
• NOCT 46
• Advantages
• Flexible
• Blends in with traditional
• roofing
• http//www.ovonic.com/unisolar.html

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Annual Fuel Consumption

• Car drives 12,000 miles annually
• Average fuel economy for a large car is 24mpg
• Total amount of fuel used per year

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Annual energy from Gasoline

• Energy / unit volume 125,000 Btu/gal
• Molecular weight 111 kg/kmol
• Available energy from fuel 66E6 kJ/yr

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Energy Conversion to Fuel Cell

• An IC Engine is approximately 20 efficient
• Energy Required to run vehicle 13.2 E6 kJ/yr
• A Fuel Cell is approximately 50 efficient
• Energy Needed from Hydrogen 26.4 E6 kJ/yr

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Required Hydrogen

• HHV for Hydrogen 141800 kJ/kg
• Molecular Weight 2 kg/kmol
• Amount of H2 needed to run car 93 kmol/yr

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Chemistry of Electrolysis

• Since mole ratio of H2O to H2 is 11, it will
  take 93 kmoles of water to create 93 kmoles of H2

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Energy Requirement from PV

• Heat of formation for water 285,830 kJ/kmol
• Required energy from PV cells 7400 kWh/yr
• Only 80 efficient 9250 kWh/yr

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Compression of Hydrogen

• FC requires fuel to be at 260 psig 275 psia
• Power to compress hydrogen
• For hydrogen k 3.445, R 4.1242
• Power to compress hydrogen 290 kWh/yr

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Results

• Without compressed hydrogen
• Total PV Energy 9250 kWh/yr
• Total PV Area 118 m2
• With compressed hydrogen
• Total PV Energy 9550 kWh/yr
• Total PV Area 122 m2
• Note average area of roof 180 m2

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Questions?