150 likes | 319 Views
Sources of Hydrogen and the Development of a Hydrogen Economy. Matt Woodson ChE 384 9/29/05. Problems with the Fossil Fuel Economy. Rising costs, shrinking supplies Air/environmental pollution Greenhouse gases Dependence on foreign producers. Why Hydrogen?.
E N D
Sources of Hydrogen and the Development of a Hydrogen Economy Matt Woodson ChE 384 9/29/05
Problems with the Fossil Fuel Economy • Rising costs, shrinking supplies • Air/environmental pollution • Greenhouse gases • Dependence on foreign producers
Why Hydrogen? • A cleaner, more efficient transportation sector • A reduction in pollution and global warming • Reduce economic dependence on foreign producers of fossil fuels
Sources of Hydrogen • Reforming of fossil fuels - Use a fuel processor to split the hydrogen from the carbon atoms in a hydrocarbon • Electrolysis of water - Use electricity to split water molecules to create pure hydrogen and oxygen
Reforming Fossil Fuels • Steam reforming of methane: High temperature steam (700o–1100oC) reacts with methane yielding syngas CH4 + H2O CO + 3H2 Additional H2 can be recovered from the CO through the lower temperature (about 130oC) water gas shift reaction CO + H2O CO2 + H2
Electrolysis • Currently much more expensive than reforming • High temperature electrolyzers might make these systems more cost efficient • To eliminate carbon emissions, hydrogen should be generated from a renewable source Solar - concentrated solar energy can generate temperatures of several hundred to over 2000oC Nuclear - High T electrolysis of steam using heat from nuclear reactors - Electrolysis using off-peak capacity
Other Sources of Hydrogen • Solar Electrochemical Water Splitting (Photoelectrochemical) -Integrate a semiconducting material and an electrolyzer into a single device • Solar Biological using Microorganisms -Photosynthetic organisms absorb light and dissociate hydrogen from oxygen
What will it cost? • Hydrogen must be $3/kg to be competitive • Reforming can produce hydrogen at $5/kg under best conditions (2003 technology) • Price of hydrogen from electrolysis is tied to cost of electricity • Hydrogen from electrolysis costs $5-6/kg undelivered (2004 technology)
Governmental Policies Relating to Hydrogen • Hydrogen Fuel Initiative Announced in 2003, Bush pledged $1.2 billion over 5 years • DOE Hydrogen Program plans to spend $64 million on research projects in the next 3 years • Renewable Energy Systems and Energy Efficiency Improvements Grant
Conclusions • Huge technical advances will be necessary for H2 to replace fossil fuels • A move towards a hydrogen economy requires the acceptance of the marketplace; cannot be driven by government policies alone • It will be several decades before the US has the capacity to produce enough H2 to impact the energy mix