Carbon capture and storage would add 50 per cent to the cost of producing ammonia in the Pilbara, the boss of one of Australia’s largest producers says, making it uneconomic without further government support compared with US fertiliser made with cheap gas and heavy subsidies under the Inflation Reduction Act.

Laurent Trost, general manager of Yara Pilbara, the Australian arm of the Norwegian fertiliser giant, said it cost the company $US300 a tonne to produce ammonium nitrate fertiliser from the Pilbara region’s offshore gas supplies, and capturing and burying the two tonnes of carbon dioxide generated for each tonne of fertiliser would lift that cost to $US450 ($674) a tonne.