Liquid Hydrogen Transport by Truck

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Introduction

This section focuses on the use of liquid hydrogen as a means of distributing hydrogen. However, when looking at the economic and well-to-wheel analysis of this mode of transport of hydrogen, one has to also consider the operating costs of the liquefier itself. A breakdown of the costs of liquefaction can be found in Section 2.6.3 of the report by Castello, Tzimas, Moretto and Peteves^[1].

In addition to the operating costs of the liquefier, one also has to consider the availability of liquid hydrogen. Currently the European industrial hydrogen market is served by three liquefiers, operated by Air Products, Air Liquide and Linde respectively and these operate at high capacity, serving the industrial hydrogen market.^[2]

To meet the needs of large scale vehicle fuelling using liquid hydrogen distribution, investments in new liquid plant would have to be made. The paper by Castello et al ¹ refers to the capital investment costs of new liquid plant.

When looking specifically at the use of liquid hydrogen as a means of distributing hydrogen, it has certain advantages over the use of gaseous trucking for large volumes and/or large distances. This is because the higher density of liquid hydrogen means that it is a far more efficient method of transporting the product, with a liquid tanker being able to carry up to ten times the volume of an equivalent gaseous tube trailer (up to 4000kg for liquid, compared with 400 kg for gaseous). The act of liquefying the hydrogen also results in product with a high level of purity, making it suitable for end users that demand a high purity product including fuel cell applications. When using gaseous supply, the purity may vary depending on the source and additional onsite purification equipment may be needed to ensure purity demands.

State of the Art / Market

Liquid hydrogen is used as a distribution mode for supply over long distances and/or when a high purity is demanded. The hydrogen is transported as a liquid in super-insulated, cryogenic tank trucks. Gaseous hydrogen is liquefied (cooled to below -253°C) and stored at the liquefaction plant in large, insulated tanks. The liquid hydrogen is then dispensed to delivery trucks and transported to distribution sites, where it is compressed and vaporised to a high-pressure gaseous product for dispensing. Over long distances, trucking liquid hydrogen is more economical than trucking gaseous hydrogen because a liquid tanker truck can hold a much larger mass of hydrogen than a gaseous tube trailer. But it takes energy to liquefy hydrogen using today's technology, liquefaction consumes more than 30% of the energy content of the hydrogen and is expensive. In addition, some amount of stored hydrogen will be lost through evaporation, or "boil off" of liquefied hydrogen, especially when using small tanks with large surface-to-volume ratios. Research to improve liquefaction technology, as well as improved economies of scale, could help lower costs (today's liquefaction units are small to meet minimal demand).

The main issues with liquid hydrogen delivery are:

• The additional investment costs. These include the investment and operation of the liquefier, as described in Section 9.3.1, but also the additional cost of the liquid delivery trailer (which is higher than the equivalent tube trailer) and liquid storage tanks and vaporisers at the customer sites. Theses costs will vary depending on the end use applications and some costs will be balanced out by the larger volumes that can be delivered. In addition, some onsite compressors needed for gaseous supply into high pressure vehicle fuelling applications could be replaced by more cost effective cryogenics pump systems. This again would depend on the pressure and form of hydrogen required for the fuelling application.
• Efficient and safe management of dispensing and boil-off. These issues are being closely looked at in current hydrogen research projects, including (in Europe) the FP6 project HyApproval.^[3]

Metrics Table

References

• Air Products
• Castello, Tzimas, Moretto and Peteves
  Techno-economic Hydrogen Transmission and Distribution Systems in Europe in the Medium and Long Term
  Report EUR 21586EN, March 2005
• Hydrogen 2003
  University of Glamorgan
• US Department of Energy [1], [2]
• High Growth Industrial Gases
  Spiritus Consulting,
• Hydrogen Delivery Model For H2a Analysis
  Ogden, University of California

Notes

1. ↑ Castello, Tzimas, Moretto and Peteves, Techno-economic Hydrogen Transmission and Distribution Systems in Europe in the Medium and Long Term, Report EUR 21586EN, March 2005
2. ↑ These plants operate in The Netherlands, France and Germany respectively.
3. ↑ www.hyapproval.org
4. ↑ Liquid tanker delivery of hydrogen is a mature method of distribution and easily be used for distribution of product for energy applications. Key issues will be justifying the economic investment in new plant and working on safety issues such as dispensing and management of boil off.
5. ↑ 'Four' refers to the major global industrial gas companies; Air Liquide, Linde Group (inc. BOC), Air Products and Praxair.
6. ↑ I'm not sure what this means
7. ↑ Ogden, University of California, Hydrogen Delivery Model For H2a Analysis