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So-called green ammonia is made by reacting nitrogen separated from air with hydrogen made by wind- or solar-powered water electrolysis. It could be an environmentally friendly fertiliser or, backers say, a safe, low-emissions fuel for ships and planes, reports Chemical & Engineering News.

A new report by the Danish catalyst company Haldor Topsoe and partners concludes that replacing conventional fuel oil with green ammonia could be a cost-effective way of reducing greenhouse gas emissions from ships.