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Problems of bulk storage and shipping of liquid hydrogen in volumes of 10,000 to 100,000 cubic meters at one bar pressure.

Number: pap. n. 01

Author(s) : SCURLOCK R.

Summary

This paper discusses concern about the safety and serious risk assessment of the large scale bulk storage, shipping and handling of liquid hydrogen.
While hydrogen is very attractive as a green fuel and energy store, some of its physical properties provide increasing problems if the proposed usage increases beyond a limit of, say, 1000 m3 of liquid hydrogen, under pressures rising to 10 to 15 bar to achieve zero boil-off, in a vacuum insulated container. Cryogenic technology is currently not able to store larger volumes in vacuum insulated tanks under pressure with zero boil-off, or even at one bar pressure with continuous boil-off. At first sight, the successful shipping and storage of bulk LNG over the past 45 years suggests a satisfactory way forward. In fact, the properties of bulk liquid hydrogen compare unfavourably with those of LNG, and the LNG technology cannot be adapted with the same degree of safety and economy.
The problems start with the large volume of boil-off hydrogen gas produced and its extreme flammability above a composition in air of only 4% hydrogen. Safe disposal of this boil-off presents a major problem, which is enhanced by the fact that the density of LH2 is 6 times less than that of LNG, and the latent heat of evaporation per unit volume is 7 times less: hence the volume of boil-off hydrogen gas is seven times greater for the same heat influx.
For ship and shore tanks with gas-purged foam insulation, the only safe purge-gas is helium which has a thermal conductivity k-value 5 times greater than nitrogen or methane purge used for LNG tank insulation. The net boil-off rate of LH2 using the conventional one metre thickness of foam insulation can therefore be expected to be 35 times larger than the working figure of 0.2% per day for stored volumes of LNG.
These and other handling problems, together with the associated hazards of disposing of the gas safely, either into the atmosphere, or flaring it off or re-condensing it, appear to make proposals for bulk liquid hydrogen usage not viable for both safety and economic reasons. This paper will review this lack of viability.

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Details

  • Original title: Problems of bulk storage and shipping of liquid hydrogen in volumes of 10,000 to 100,000 cubic meters at one bar pressure.
  • Record ID : 30021679
  • Languages: English
  • Source: Cryogenics 2017. Proceedings of the 14th IIR International Conference: Dresden, Germany, Mai 15-19, 2017.
  • Publication date: 2017/05/15
  • DOI: http://dx.doi.org/10.18462/iir.cryo.2017.0001

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