In January 2020, the Global Maritime Forum published new analysis that calculates "the capital investment needed to achieve decarbonization" in line with the International Maritime Organization's Initial GHG Strategy. The result of this analysis, which assumes that ammonia will be "the primary zero carbon fuel choice adopted by the shipping industry," is an aggregate investment of between $1 trillion and $1.4 trillion dollars, from 2030 to 2050, or roughly $50 to $70 billion per year across two decades.
Ship-side costs are only 13% of this number. The bulk of the investment will be directed towards green ammonia plants for maritime fuel synthesis. By 2050, this global fuel demand is estimated to be more than 900 million tons per year of green ammonia, more than five time today's total global output of conventional ammonia.