Hydrogen Storage, Electrolysis and Fuel Cells
Hydrogen: The Storage Problem
October 6, 2007
We must explore all possible forms of energy production and storage. One of them is particularly appealing. It is water electrolysis. Hydrogen is inherently a non-polluting fuel since the product of its combustion is ... water. Therefore, one can imagine dreaming of vast installations occupying wide desert areas, by the sea, splitting water molecules (for example, seawater) constantly.
A reader, an engineer named Alain Hubrecht from Brussels, provides some additional information about hydrogen as a fuel (especially for automobiles).
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Regarding hydrogen storage, some more precise information:
Most of the current hydrogen-powered cars are equipped with 350-bar tanks (DaimlerChrysler recently announced that its supplier for its 60 F-Cell would be), but GM is already working on prototypes with 700-bar tanks. This has a cost, because all refueling stations will then have to be equipped with 700-bar compressors, which are expensive, hence the interest in the solution presented by the company (TOHS, the result of a joint development between and ) which reliably and compactly stores hydrogen at a more reasonable pressure of 105 bars.
The TOHS innovation consists of a metal alloy that absorbs hydrogen and releases it when heated. This new development would be more efficient than traditional metal hydrides, as demonstrated by the Toyota Prius, which TOHS converted from a thermal engine to run on hydrogen. Its 60-liter tank can hold 3 kg of hydrogen, giving the car a 200 km range, whereas a conventional 350-bar tank of the same volume would only allow the car to travel 100 km.
( ) Before considering mass production of hydrogen-powered vehicles, it is necessary to look at the disadvantages of hydrogen: the cost of production, the cost of storage and its distribution. The cost of hydrogen production reaches 8 €/kg in Germany. Even considering that the energy value of a kilogram of hydrogen is equivalent to three kilograms of gasoline, it still comes out to a price seven times higher than the price of gasoline without taxes!
Similarly, hydrogen storage on board a car is very expensive: 1,000 €/kg. If we consider that one kilogram of hydrogen is needed to travel 100 km, then 5 kg of hydrogen would be needed to travel 500 km (I leave you to calculate the storage cost). Of course, in a few years, manufacturers will mass-produce hydrogen vehicles, which will allow the storage cost to decrease (estimated between 200 and 500 € per kg). The Americans, for their part, aim for a cost of about 70 €/kg by 2015.
Moreover, it is not only hydrogen storage that is expensive, but also the fuel cell itself. Currently, it is 50 to 100 times more expensive than a thermal engine. A fuel cell costs 5,000 €/kW compared to 50 €/kW (or 37 €/hp) for a conventional engine. Manufacturers hope to reduce this price to between 200 and 1,000 €/kW by 2010. The prices are so high because Nafion (the polymer used in PEMFC fuel cells) costs 400 €/m²!
(Source:
)
Regarding hydrogen storage, some more precise information:
Most of the current hydrogen-powered cars are equipped with 350-bar tanks (DaimlerChrysler recently announced that its supplier for its 60 F-Cell would be), but GM is already working on prototypes with 700-bar tanks. This has a cost, because all refueling stations will then have to be equipped with 700-bar compressors, which are expensive, hence the interest in the solution presented by the company (TOHS, the result of a joint development between and ) which reliably and compactly stores hydrogen at a more reasonable pressure of 105 bars.
The TOHS innovation consists of a metal alloy that absorbs hydrogen and releases it when heated. This new development would be more efficient than traditional metal hydrides, as demonstrated by the Toyota Prius, which TOHS converted from a thermal engine to run on hydrogen. Its 60-liter tank can hold 3 kg of hydrogen, giving the car a 200 km range, whereas a conventional 350-bar tank of the same volume would only allow the car to travel 100 km.
( ) Before considering mass production of hydrogen-powered vehicles, it is necessary to look at the disadvantages of hydrogen: the cost of production, the cost of storage and its distribution. The cost of hydrogen production reaches 8 €/kg in Germany. Even considering that the energy value of a kilogram of hydrogen is equivalent to three kilograms of gasoline, it still comes out to a price seven times higher than the price of gasoline without taxes!
Similarly, hydrogen storage on board a car is very expensive: 1,000 €/kg. If we consider that one kilogram of hydrogen is needed to travel 100 km, then 5 kg of hydrogen would be needed to travel 500 km (I leave you to calculate the storage cost). Of course, in a few years, manufacturers will mass-produce hydrogen vehicles, which will allow the storage cost to decrease (estimated between 200 and 500 € per kg). The Americans, for their part, aim for a cost of about 70 €/kg by 2015.
Moreover, it is not only hydrogen storage that is expensive, but also the fuel cell itself. Currently, it is 50 to 100 times more expensive than a thermal engine. A fuel cell costs 5,000 €/kW compared to 50 €/kW (or 37 €/hp) for a conventional engine. Manufacturers hope to reduce this price to between 200 and 1,000 €/kW by 2010. The prices are so high because Nafion (the polymer used in PEMFC fuel cells) costs 400 €/m²!
(Source:
)