Why we should assess CO2 storage potential in New Zealand?

New Zealand industries emit millions of tonnes of CO2 each year that could be captured and stored underground instead of being released to the atmosphere (where it contributes to global warming).

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CO2 could be captured from large industrial sites such as the Huntly power station, steel and aluminium foundries, and other places where large amounts of fossil fuels are burned for energy. However, retro-fitting capture of CO2 is expensive and so far we have not tried to do this in New Zealand. If large new industrial sources are planned then it would be advisable to consider including carbon capture technology.

Significant amounts of natural CO2 occur in some of New Zealand’s natural gas accumulations and, where this is more than 10% it generally needs to be stripped out before the gas is used. For example, at Kapuni the natural gas contains around 44% CO2. This is stripped out by Vector; while some of the pure CO2 is used, the remainder is vented to the atmosphere. In order to minimise atmospheric increases in CO2, it would be advisable to avoid venting and instead CO2 from expanded or new operations should be used or stored underground.

Liquid CO2 can be used in enhanced oil recovery (EOR), whereby the CO2 flushes out oil that would otherwise remain trapped in small pore spaces underground. Typically less than 50% of the oil in a discovery is recoverable, but EOR can sometimes increase this to 80-90%. EOR means more efficient use of known resources and reduces the need for additional exploration. It also results in the permanent storage of CO2.

A new major gas find worth billions of dollars, but containing CO2, could trigger the need for CCS. It is therefore advisable that we know where we can store CO2 - and how much we can store – so that we are prepared for the deployment of CCS in New Zealand. This could happen at any time, for example when public opinion requires it, when carbon taxes rise to levels that make it economic, or when a major gas discovery necessitates it. At GNS Science, this preparation is done in part via research and in part by consulting (which broadens our experience, and helps to reduce emissions overseas – it’s a global problem that impacts New Zealand).