30-04-2014, 03:21 PM
HYDROGEN FUEL CELLS
HYDROGEN FUEL.ppt (Size: 49 KB / Downloads: 66)
Molecular Hydrogen Facts
Three times energy content of gasoline (120 Mj/kg vs. 44Mj/kg)
Cost of liquefying it is 30 to 40% of its energy content
Pipelines are 50% greater diameter than for gas (for equivalent energy transmission rate), so more $.
Distribution doubles cost of production ($1.03/kg).
Flammable concentration has a wide spread from 4% to 75%.
Molecular Hydrogen Generation
Three different scales of generation: Central Station, Midsize, and Distributed.
Central Station: 1,080,000 kg/day would support 2M cars. Distributed by pipeline. Generated by fossil fuel or nuclear energy.
Midsize: 21,600 kg/day would support 40k cars. Distributed by cryogenic truck. Generated by natural gas or biomass
Distributed: 480 kg/day would support 800 cars. No distribution system needed. Renewable fuels used.
Hydrogen Generation
Electrolysis: from fossil fuels or renewable energy sources
Fossil Fuels requires carbon sequestering (next slide)
Hydroelectric, Nuclear Energy, Photovoltaic, grid based energy, wind power, have either periodic generation, which may not match usage, or have constant generation, which does not match usage.
Energy storage at peak times is a problem for these energy sources that hydrogen generation could solve.
Cost for all distributed (renewable) sources is two to five times cost of gasoline (2004)
Carbon Dioxide Sequestering
No advantage to Hydrogen production from fossil fuels as far as reducing Carbon Dioxide is concerned. Yet this is the cheapest method to generate Hydogen.
Currently, only 4% of Hydrogen is from electrolysis; the rest is from coal, oil and natural gas, which contains about 10% CO2 as well as the Hydrogen.
Norway injects CO2 into saline aquifer.
Los Alamos study of CO2 injection into magnesium formations (Peridotites, serpentinite, Gabbro, and Basalt)
Costs about $8 per ton of CO2 disposed. Permanent and no legacy problems for future generations.
Hydrogen production--Renewable fuels
From wind energy. Electrolyze water. Wind is the most cost effective renewable energy source: $0.04 to $0.07/kWh costs about $6.64/kg per H2 if grid back up used.
From Biomass. Only 0.2 to 0.4% of solar energy converted to H2. Costs $7.05/kg by gasification, not including fertilizers and land degradation.
From Solar energy. Either by electrolysis (Photo voltaic) or using photoelectrochemical cell (in a early stage of development). Cost now is $28.19/kg and solar energy is only available 20% of the time.
Hydrogen safety
Small leak more flammable than for gasoline, but more likely to disperse, so ignition less likely.
Static spark can ignite, so ground during transfer.
Detonation more likely than with gasoline because of wider flammable concentration and higher flame speed.
Need high pressure to transfer efficiently: 5-10k psi.
Odorless, burns with a blue flame. Small molecule precludes adding scent molecule.
HYDROGEN FUEL.ppt (Size: 49 KB / Downloads: 66)
Molecular Hydrogen Facts
Three times energy content of gasoline (120 Mj/kg vs. 44Mj/kg)
Cost of liquefying it is 30 to 40% of its energy content
Pipelines are 50% greater diameter than for gas (for equivalent energy transmission rate), so more $.
Distribution doubles cost of production ($1.03/kg).
Flammable concentration has a wide spread from 4% to 75%.
Molecular Hydrogen Generation
Three different scales of generation: Central Station, Midsize, and Distributed.
Central Station: 1,080,000 kg/day would support 2M cars. Distributed by pipeline. Generated by fossil fuel or nuclear energy.
Midsize: 21,600 kg/day would support 40k cars. Distributed by cryogenic truck. Generated by natural gas or biomass
Distributed: 480 kg/day would support 800 cars. No distribution system needed. Renewable fuels used.
Hydrogen Generation
Electrolysis: from fossil fuels or renewable energy sources
Fossil Fuels requires carbon sequestering (next slide)
Hydroelectric, Nuclear Energy, Photovoltaic, grid based energy, wind power, have either periodic generation, which may not match usage, or have constant generation, which does not match usage.
Energy storage at peak times is a problem for these energy sources that hydrogen generation could solve.
Cost for all distributed (renewable) sources is two to five times cost of gasoline (2004)
Carbon Dioxide Sequestering
No advantage to Hydrogen production from fossil fuels as far as reducing Carbon Dioxide is concerned. Yet this is the cheapest method to generate Hydogen.
Currently, only 4% of Hydrogen is from electrolysis; the rest is from coal, oil and natural gas, which contains about 10% CO2 as well as the Hydrogen.
Norway injects CO2 into saline aquifer.
Los Alamos study of CO2 injection into magnesium formations (Peridotites, serpentinite, Gabbro, and Basalt)
Costs about $8 per ton of CO2 disposed. Permanent and no legacy problems for future generations.
Hydrogen production--Renewable fuels
From wind energy. Electrolyze water. Wind is the most cost effective renewable energy source: $0.04 to $0.07/kWh costs about $6.64/kg per H2 if grid back up used.
From Biomass. Only 0.2 to 0.4% of solar energy converted to H2. Costs $7.05/kg by gasification, not including fertilizers and land degradation.
From Solar energy. Either by electrolysis (Photo voltaic) or using photoelectrochemical cell (in a early stage of development). Cost now is $28.19/kg and solar energy is only available 20% of the time.
Hydrogen safety
Small leak more flammable than for gasoline, but more likely to disperse, so ignition less likely.
Static spark can ignite, so ground during transfer.
Detonation more likely than with gasoline because of wider flammable concentration and higher flame speed.
Need high pressure to transfer efficiently: 5-10k psi.
Odorless, burns with a blue flame. Small molecule precludes adding scent molecule.