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What is hydrogen? | Why hydrogen energy? | The hydrogen energy cycle | Hydrogen web sites
Hydrogen (H2) is a gas that is normally not encountered on the surface of our Earth. Hydrogen is almost always chemically bound in a multitude of compositions, such as hydrocarbons and water. Water is abundantly available but the separation from the hydrogen and oxygen atoms requires a considerable amount of energy. The hydrogen gas must then be pressurized and frequently stored in its liquid state at a temperature of minus 253 degrees centigrade.
It is only by this process that Hydrogen becomes an energy carrier, which can then be used for various purposes, such as powering rockets, fuel cells and engines for motor cars.
The production of hydrogen gas by means of electrolysis of water requires electicity, which in turn must be produced "sustainably"1 by solar panels, wind mills or water dams.
Why Hydrogen? [top]
Fossil energy will run out: oil and natural gas within one to two generations; coal could last for some eight generations, at present consumption levels.2
The burning of fossil fuels increases the carbondioxide content of the Earth atmosphere, which in turn leads to harmful climate change and global warming.3
Some people see Hydrogen as the solution for our energy and carbondioxide problems. They believe or hope that hydrogen technology will allow us to maintain present societal structures, consumption levels and mobility patterns. This is questionable, however, for a variety of reasons.
Fossil energy (oil, gas, coal) is used for manufacturing, heating and transportation. Hereafter we will mainly discuss the proposal of using hydrogen for transporation, since this appears to be the main thrust of hydrogen research.
The Hydrogen Energy Cycle in Transportation [top]
Basic figures (approximations) for hydrogen energy used for a hydrogen fuell cell - electric car in comparison with petrol powered piston engin car:
(1) Solar panels (Photo Voltaics) can generate electricity at 90 - 100 Watt per square meter. In other words, 10 square meter of solar panels can produce 1 kWh of electricity in one hour.
(2) Producing 1 cubic meter Hydrogen gas costs 4 kilowatthour, by means of electrolysis of water.
(3) Therefore the production of 1 m3 hydrogen gas requires 40 m2 of solar panels.
(4) One cubic meter of hydrogen gas at normal temperature is equivalent to one litre of liquid hydrogen at minus 253.6 degrees centigrade: 1 m3 H2G = 1 L H2L.
(5) The energy contained in one litre of petrol is equivalent to 10 kWh electricity (at 100 % conversion efficieny).
(6) Petrol consumption of a small passenger car: 7 L /100 km = 6.7 kg / 100 km
(7) Hydrogen: 1.8 kg H2L = 25 L H2L (density: 70 gram/L)
(8) The energy contained in 6.7 kg of petrol is equivalent to the energy of 1.8 kg of liquid hydrogen, or 25 litre H2L, or enough for 100 km.
(9) At current market conditions one litre of liquid hydrogen (H2L) costs SFr. 4.00 (US$ 2.70). At a consumption of 25 L H2L / 100 km the fuel costs will be SFR.100.00 / 100 km.
Energy conversion efficiency rates to be considered:
(11) generated energy in the useful lifetime divided by the total installed energy in the solar panels
(12) electrolysis process
(13) pressurising and cooling to obtain liquid hydrogen
(14) fuel cell - electric motor and piston engine efficiencies
A hydrogen economy - not subsidised by fossil fuels or atomic power - must be energetically self-sufficient. This means that all costs for production, distribution and conversion into work must be covered by the net energetic production. Costs include producing the equipment as well as energetic conversion losses. To our knowledge, energetic efficiency rates are, approximately:
[- converting solar energy into electricity by solar panels: 0.1]
- electrolysis of water: 0.3
- pressurising H2: 0.8
- liquifying H2 (minus 253.6 centigrades): 0.6
- transportation and storage: 0.9 (???)
- fuel cell: 0.4
- electric motor (e.g. as engine for a private car): 0.92
Multiplying these efficiencies (excluding the first one for the solar cells) results in an overall energetic efficiency of 0.0477 or 4.77 per cent.
Which would indicate that 95 per cent of the solar cell electricity production dissappears as losses.
And this does not yet include the hydrogen needed to manufacture the equipment cum infrastructure cum application for mobility or for stationary purposes.
If the above calculation is correct, it may be more efficient to use solar cells' electric power through different techniques/technologies and for the most important human undertakings (food, shelter, clothing, i.e. basic human survival and happiness)?
Which car manufacturer has calculated the overall efficiency rate for hydrogen as an energy carrier, incorporating all energy conversion rates and energy investment in the means of hydrogen production, storage, transportation and fuel cell - electric motor drive, in comparison with conventional crude oil extraction, refining, storage, transportation and petrol engine drive, for a small private car.
Thanks for your feedback and advice
Hydrogen web sites: [top]
knowledge linksHydrogen glossary
Fuel Cell Glossary (pdf file)
Energy Conversion Tables
USA & CanadaH2 information Network (USA Department of Energy)
American Hydrogen Association
National Hydrogen Association
California Hydrogen Business Council
1: "Sustainability" refers to a a situation or a process that can go on for a very long time, in principle forever, without depleting resources and without increasing impact on the environment back
2: A "generation" represents 25 years. Our industrial age started ten generations ago. We learned to write 240 generations ago. Our human species "homo sapiens sapiens" exists since at least 4000 generations. Compare Population graph back
3: See Climate change links back
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