Environmental Technology

Opinion: New Zealand facing big environmental, cultural hurdles for green hydrogen economy

Consuming water has cultural implications

Freshwater has enormous significance to iwi and hapū. However, their views on hydrolysis as a consumptive use of water are not widely understood. If cultural complexity is ignored, hydrogen infrastructure or processes may fail to achieve an appropriate fit within Aotearoa New Zealand society and the technology could be orphaned.

Instead, we could start addressing this early through wānanga with representatives from a wide range of potentially affected iwi. Recognizing and addressing cultural concerns at the outset will allow Māori to shape how the technology is developed and to share in the economic benefits of a hydrogen economy. The intention is to better understand how green hydrogen technologies and infrastructure could belong in Aotearoa New Zealand.

Supposing we are willing and able to make this vast quantity of hydrogen, our experience with other fuels suggests we would need about a month’s worth in storage at any given time. Storage helps to smooth fluctuating market demand, takes advantage of seasonal excess of renewables (in very windy, very sunny weeks) and provides emergency reserves for “dry year” crises.

Storing hydrogen underground

Unfortunately, hydrogen can’t be stored as a liquid except in specialized containers that keep it at extremely low temperatures. Like a freezer, this is always consuming energy.

Hydrogen could be kept in special high-pressure tanks, but we would need more of these tanks than we have people in New Zealand. These tanks would be costly, cover large tracts of productive land and would be prone to damage by natural hazards. Where would they all go?

Scientists have been looking at the possibility of storing hydrogen underground, in great caverns carved in salt or in old oil and gas fields.

We already do this with natural gas in Taranaki. When it’s not needed, gas is injected into an old field called Ahuroa and then extracted as required. Underground storage of gas (methane) is common practice, providing energy resilience. For example, given the disruptions caused by the war in Ukraine, Germany is accelerating gas storage in geological reservoirs in time for winter.

We have recently shown that there may be enough space in other Taranaki rock reservoirs to store hydrogen underground. But it won’t be easy.

We know the gas can react with certain kinds of rock. It can even be a meal for hungry microbes. Both these processes would consume a valuable fuel. But predicting whether they will happen requires special laboratory experiments that can replicate the extreme pressure and temperature three kilometers below the ground.

We are also still learning how to predict how hydrogen will move underground. We know that some of the injected gas will never come back out. This is the “cushion” that acts a bit like a spring that pushes the other hydrogen back to the surface.

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