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Compressed hydrogen in hydrogen tanks at 350 bar (5,000 psi) and 700 bar (10,000 psi) is used for mobile hydrogen storage in hydrogen vehicles. It is used as a fuel gas. 

Compressed hydrogen is a storage form where hydrogen gas is kept under pressures to increase the storage density. Compressed hydrogen in hydrogen tanks at 350 bar (5,000 psi) and 700 bar (10,000 psi) is used for hydrogen tank systems in vehicles, based on type IV carbon-composite technology. Car manufacturers have been developing this solution, such as Honda or Nissan.

Hydrogen gas has good energy density by weight, but poor energy density by volume versus hydrocarbons, hence it requires a larger tank to store. A large hydrogen tank will be heavier than the small hydrocarbon tank used to store the same amount of energy, all other factors remaining equal. Increasing gas pressure would improve the energy density by volume, making for smaller, but not lighter container tanks. Compressed hydrogen is estimated to cost about 2.1% of the energy content to power the compressor for a large scale underground facility such as an underground cavern or aquifer from 1 to 200 bar. Higher compression without energy recovery will mean more energy lost to the compression step. Compressed hydrogen storage can exhibit very low permeation.

The first type IV hydrogen tanks for compressed hydrogen at 700 bars (70 MPa; 10,000 psi) were demonstrated in 2001, the first fuel cell vehicles on the road with type IV tanks are the Toyota FCHV, Mercedes-Benz F-Cell and the GM HydroGen4. 

Various applications have allowed the development of different H2 storage scenarios. Recently, the Hy-Can consortium has introduced a small one liter, 10 bars (1.0 MPa; 150 psi) format. Horizon Fuel Cells is now selling a refillable 3 megapascals (30 bar; 440 psi) metal hydride form factor for consumer use called HydroStik.






The allure of the hydrogen economy is plain, splitting plain ordinary water using electrolysis to obtain oxygen and hydrogen gas is like a dream come true, especially if we can generate free electricity using solar cells and wind turbines to split the water.


Then the hydrogen is free right. But is the electricity free?


No, not really.


There is a cost, including the cost of manufacturing the solar panels or wind turbines and the transmission line installation and maintenance.


Where there is a cost, then we have to consider payback time and working life. If we can use most of the solar and wind energy directly to power vehicles, we make the best of the working life of our energy harvesting apparatus. And that means reduced greenhouse gases, so a reduced carbon footprint for the human race in an anthropogenic fight against climate change.







A water molecule is formed by two elements: two positive Hydrogen ions and one negative Oxygen ion.


The water molecule is held together by the electromagnetic attraction between these ions. When electricity is introduced to water through two electrodes, a cathode (negative) and an anode (positive), these ions are attracted to the opposite charged electrode. Therefore the positively charged hydrogen ions will collect on the cathode and the negatively charged oxygen will collect on the anode.

When these ions come into contact with their respective electrodes they either gain or lose electrons depending on there ionic charge. (In this case the hydrogen gains electrons and the oxygen loses them) In doing so these ions balance their charges, and become real, electrically balanced, bona fide atoms (or in the case of the hydrogen, a molecule).

The reason this system isn't very efficient is because some of the electrical energy is converted into heat during the process.








EUREKA - Hydrogen is the most abundant element in the universe. With the "green-energy" craze and talk of powering our future oil-free economy on hydrogen, it has received much attention in the last few decades. Learning about this potential fuel of the future is important and interesting, but not without snags, and these are for anyone to seek to overcome.



Fuel Cell animation


ANIMATION - A fuel cell converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity.

The other electrochemical device that you may be familiar with is the battery. A battery has all of its chemicals stored inside, and it converts those chemicals into electricity too. This means that a battery eventually "goes flat" and you have to recharge it.

With a fuel cell, chemicals constantly flow into the cell so it never goes flat - as long as there is a flow of chemicals into the cell, the electricity flows out of the cell. Most fuel cells in use today use hydrogen and oxygen as the chemicals.

The problem with fuel cells is the storage technology. Batteries are the storage medium and supply all in one. Fuels cells need an external container to hold liquid hydrogen or hydrogen combined as a metal hydride to feed the unit that combines the gases to make electricity.


























USA - In 2003, President Bush announced a program called the Hydrogen Fuel Initiative (HFI) during his State of the Union Address. This initiative, supported by legislation in the Energy Policy Act of 2005 (EPACT 2005) and the Advanced Energy Initiative of 2006, aims to develop hydrogen, fuel cell and infrastructure technologies to make fuel-cell vehicles practical and cost-effective by 2020. Obviously, the legislation did not work, or we'd seen hydrogen cars selling like hot cakes. Whereas, there are significant sales of battery electric cars.


The United States has dedicated more than two billion dollars to fuel cell research and development so far. Yet the basics principles of climate change is to find the best way to use less energy to achieve the same goal. Of course we have to explore all avenues before deciding on what works best. Thomas Edison found 1,000 ways not to make a light bulb before inventing his carbon filament version that succeeded. Joseph Swan in the UK filed a similar patent before the more famous US inventor. Keep at it chaps.



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