Sustainability of cruise ship fuel systems: Comparison among LNG and diesel technologies

Liquefied natural gas (LNG) is becoming a viable, “green” alternative to marine fuel oil for ship propulsion. The present study investigates the expected impact on sustainability of innovative ship fuel systems based on the use of LNG. For the sake of comparison, conventional technologies for ship fuel systems, based on marine fuel oil, were considered in the analysis. A specific methodology was adopted to support the sustainability assessment, based on the evaluation of key performance indicators addressing three fundamental domains: environmental impact, economic feasibility and inherent safety of the fuel system. The results obtained allow determining a sustainability fingerprint of the alternative fuel systems considered and a performance ranking. The LNG-based fuel system technologies show a better sustainability performance than the conventional marine fuel technologies. The relevant environmental benefits associated with LNG fuel systems point out the critical role of environmental impact reduction in driving the design of innovative fuel systems for marine applications.