Environment & Energy

[font face=Serif]September 1999 • NREL/TP-570-27079

[font size=5]Survey of the Economics of Hydrogen Technologies[/font]

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[font size=4]Hydrogen Storage Technologies[/font]

[font size=3]Use of hydrogen as an energy carrier requires that it be stored and transmitted. The primary methods for hydrogen storage are compressed gas, liquefied hydrogen, metal hydride, and carbon-based systems. Most of these systems may be used either for stationary applications or for onboard vehicle storage. Long term (i.e., ~ 100 days), seasonal storage of hydrogen is generally in the form of chemical hydrides. In the following section, each hydrogen storage technology will be evaluated as a stationary system and where applicable, onboard use will be discussed. The stationary systems, except chemical hydrides, will be evaluated for both 1-day and 30-day storage periods. All capital costs are expressed in $/GJ of annual throughput.

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[font size=4]Chemical Hydrides[/font]

[font size=3]Chemical hydrides constitute another method for storing hydrogen, primarily for seasonal storage (i.e., > 100 days). Seasonal storage would be an option for countries such as Canada that have a surplus of hydropower during the summer, but an energy deficit during the winter (Newson et al. 1998). Numerous chemical hydrogen carriers, including methanol, ammonia, and methyl-cyclohexane, have been proposed. Use of a chemical system is advantageous because the transport and storage infrastructure is already in place, the technology is commercial, and liquid storage and handling are easier.

Newson et al. (1998) analyzed seasonal storage using a methylcyclohexane-toluene-hydrogen (MTH) storage system. This analysis assumes that the capital cost for a single day of storage with this system would be $1,400/GJ, dropping to $15/GJ at 100 days. This significant drop is because the dehydrogenation plant is the same size whether the storage is daily or seasonal (Newson et al. 1998). Thus, a tremendous economy of scale can be realized.

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