Iran war: Pre-conflict report warned diesel stocks might not be sufficient
Monday, 23 March 2026
Diesel would run out first if New Zealand were ever to be completely cut off from fuel supplies, a report produced for the Government appears to confirm.
The report implies that the country’s current stock level of 47 days’ worth of diesel in storage or on the way to New Zealand could be stretched out to last about eight months if it was immediately conserved for only critical functions.
Conservation measures that extreme are not currently being considered by the Government.
The Fuel Security Study was produced by consultants Castalia and Envisory for the Ministry of Business, Innovation and Employment and published on February 12, just 16 days before the Middle East conflict began.
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It raised particular concerns about diesel stocks.
Government rules requiring fuel importers hold 28 days’ worth of petrol provided a “good buffer for disruption” and the mandated 24-day minimum for jet fuel “should provide a sufficient buffer for operational disruptions”, the consultants said.
But at the statutory minimum of 21 days, diesel stocks “might not be sufficient to manage expected disruption events”, it warned.
Despite the lower stock requirement for diesel, the consultants’ report makes clear it is harder to cut back on the use of the fuel in a crisis.
When Covid level-4 restrictions were in place in 2020, petrol consumption dropped by between 75% and 80% of its normal level and the consumption of jet fuel fell between 70% and 80%, the consultants found.
But the consumption of diesel fell by only 60% to 70%.
“Critical functions of state and essential services such as lifeline utilities” accounted for about 5% of diesel use and about 3% of petrol consumption, they said.
The consultants said there was not good information on how much diesel was needed to keep other “critical transport” functions such as food distribution and other essential workers on the road, suggesting that was a knowledge-gap that should be addressed.
But they estimated they would account for another 5% to 15% of diesel use, implying it might be possible to cut diesel use by 80% from its normal level without compromising critical services.
The Government had been in the process of raising the minimum holding requirement for diesel to 28 days, but that change would not kick in until 2028.