Minimizing Boil-Off Losses in Liquefied Natural Gas Transportation

Natural gas (NG) is the cleanest fossil fuel, which is most popular and economical after crude oil. Liquefied natural gas (LNG) is the most economical way of transporting NG over long distances. Because of LNG transportation and storage at -163 degrees C, boil-off losses are an unavoidable reality While these are significant, few systematic studies on boil-off exist in the literature In this work, we perform rigorous, realistic, detailed, and extensive dynamic simulation of boil-off during various steps of LNG transportation, study the effects of various factors such as nitrogen content, tank pressure, ambient temperature, voyage length, etc., and analyze the results. On the basis of our simulations, we determine optimal heels for several scenarios of lean LNG transportation. Our analysis shows that heel can be reduced by up to 40% for a typical long voyage of 20 days, compared to the usual industrial practice of 5% of the cargo, and the reduction is significantly more for the shorter voyages. Our computations suggest savings of millions of dollars from heel optimization alone in LNG transportation.