Hydrogen is like electricity and steam, it carries energy, but is hard to store. |
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Hydrogen storage under pressureHydrogen is difficult to store because it is difficult to liquefy. It's critical temperature is -240 0C at 13 bar (13 atmos.). This means it will not liquefy above -240 0C (at 13 bar), no matter what pressure is applied. Even when it is liquefied, the density is only 0.03. (water is 1.0). Petrol has nearly twice the hydrogen in the same volume of hydrogen. The ways of storing hydrogen are: Cryogenic liquid - must be kept below -240 0C at 13 bar Pressurised gas - Car makers Honda and Nissan are working with hydrogen at 350 and 700 bar (5,000 and 10,000 psi). The energy of compression needs to be recovered as the hydrogen is consumed. If the energy is recovered during decompression only 2% of the energy for compression is lost.. The mass of the tank is a disadvantage. It weighs twice as much as the hydrogen. Underground pressurised storage. ICI has for many years stored hydrogen underground in old salt domes. Some researchers have investigated underground hydrogen storage to provide grid energy storage for intermittent energy sources, like wind power. Carbon nanotubes will store hydrogen, but only about 1% by mass |
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Hydrogen storage in a chemicalHydrogen can be stored chemically as hydrides such as MgH2, NaAlH4, LiAlH4, LiH, LaNi5H6, TiFeH2 and PdHx (x<1) The challenge is to find a hydride that releases the hydrogen at 100oC, and combines or recharges at 700 bar or less. Carbohydrate such as starch and sugar are very efficient carriers of hydrogen. Some researchers claim that sugar can be the most efficient fuel for cars. The sugar is converted to hydrogen by an on-board reformer, then used in a fuel cell. After a biomass charged battery vehicle, it was the most fuel efficient vehicle. More Ammonia NH3 is a useful way to store hydrogen at room temperature. It can burn in an internal combustion engine. Ammonia borane H3NBH3 Wikipedia University of Oregon chemists have developed a boron-nitrogen-based liquid-phase storage material for hydrogen that works safely at room temperature and is both air- and moisture-stable More Metal organic frameworks. Very porous substances will absorb up to 7% hydrogen by weight at 77oK and one bar of pressure. Clathrate hydrates, glass cailliaries and glass microspheres, are being researched. |
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In TolueneJapan's largest petroleum wholesaler, JX Holdings, has devised a technology to transport large volumes of hydrogen safely in liquid form By dissolving hydrogen in toluene, a liquid derived from crude oil, the firm will be able to transport the liquid at ordinary temperatures and pressure. Using a proprietary catalyst, hydrogen will then be revaporized at the pump. Source |
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ResearchA New storage mediumA team of engineers from the University of New South Wales has made an exciting discovery that it hopes will help advance the cause of hydrogen fuel as a viable alternative energy source – particularly for use in hydrogen fuel cell vehicles.
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Magnesium HydrideQueensland company Hydrexia has patented a process of storing hydrogen on magnesium hydride doped with nickel or similar transition metals. These metals act as catalysts. It stores 6.5 - 7% of it's mass as hydrogen. The magnesium hydride has an energy density of 2.332 kWh/Kg. It seems to work at atmospheric pressure, but the patent language is difficult to follow.
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Cella hydrogen storageThe Cella technology is based around the encapsulation and nano-structuring of chemical hydrides in plastic. This means that they can be handled in air, and allows the hydrogen to be released quickly and cleanly upon heating. We make them into plastic like pellets; heating one gram of Cella’s pellets will produce one litre of hydrogen (at normal pressures and temperatures). Cella materials have achieved 9wt% weight percentage of hydrogen. Source: http://www.cellaenergy.com/index.php?page=technology |
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Carbon nanotubes from chicken feathersIf bird feathers are heated without air between 350-450oC,, they form hollow carbon nanotubes. These tubes can store hydrogen because they have such a large surface area and hydrogen bonds strongly to any carbon exposed on the surface. |
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Hydrogen for storing electricityThe processes for storing electricity via hydrogen production is not very efficient, about 20-25%. You lose 75-80% of the energy during the AC to hydrogen and back to AC again. To make a profit the electricity sell price would need to be more than 5X the buy price. No doubt, this will improve with time. |
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