A new life for LNG tanks

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A new life for LNG tanks

21-07-2022 | Posted by Joaquín Martí

Apart from other applications outside the energy area, natural gas has an obvious role in helping us transition towards a less carbon intensive generation of electricity, a role that is currently being recognised by institutions such as the European Union. Some of the advantages of natural gas, together with Principia’s experience in this context, were already discussed in a previous post, entitled “Environmentally friendly gas”.

An export facility for LNG (liquefied natural gas) is a complex and expensive installation, where the natural gas is received, treated, refrigerated, liquefied, stored, and loaded onto gas tankers for transportation. An import facility is somewhat simpler, though it still needs to unload the LNG, store it, vaporise it, and resend it.

At times, it occurs that an import facility must be reconverted into an export one. This is not very frequent but may happen when new technologies, such as fracking, and an increasing price of the commodity allow developing gas resources that previously were not economically accessible. Currently the main examples are found in North America.

Clearly, this type of change implies an essentially new plant since the liquefaction and vaporisation processes involve very different operations. But the site, the permit, and some elements of the facility, such as the loading/unloading jetties and their pipelines, would not need much modification.

One would think that the LNG storage tanks would be directly reusable. However, reality is a bit more complicated, because the change of use entails some new conduits entering the tanks, thus modifications to the roof platform, and so on.

Also, the regulations that govern the design of the tanks are updated every few years, thereby affecting, at least, the supporting calculations; the seismic requirements and the allowable crack width in the concrete during a major spill are recent examples.

Principia has carried out those activities for repurposed tanks and knows that they are not always straightforward. Consider that, before construction, the design of the tank can be modified to satisfy the rules; but after construction, both the design and the rules are already fixed and, ideally, should be shown to be compatible. This may require all the resources that only well-trained and experienced practitioners can deploy.

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