Two of the world's biggest fertilizer producers, CF Industries Holdings Inc and Yara International Asa, are seeking to cash in on the green energy transition by reconfiguring ammonia plants in the United States and Norway to produce clean energy to power ships.The consumption of oil for transportation is one of the top contributors to global greenhouse gas emissions that cause climate change, and fertilizer producers join a growing list of companies adjusting their business models to profit from a future lower-carbon economy. By altering the production process for ammonia normally usedfor fertilizer, the companies told Reuters they can producehydrogen for fuel or a form of carbon-free ammonia usedeither as a carrier for hydrogen or as a marine fuel topower cargo and even cruise ships.