Waste heat recovery from marine engines and their limiting factors: Bibliometric analysis and further systematic review

To cope with present energy and climate crises, maximization of energy use becomes essential. Maritime transport is the core of international trade and the majority of vessels are equipped with marine engines for propulsion and power generation. This paper provides an exhaustive state of the art review on enhancing efficiency technologies based in waste heat recovery and applicable to marine engines. A bibliometric analysis followed by a systematic review based on the PRISMA 2020 approach is presented in order to identify current used systems, not implemented but available technologies and non-explored heat sources. From a wide query on Scopus and Web of Science databases, 576 results were obtained for the bibliometric analysis. Further selection of the most relevant journal articles gave a total of 35 studies, 30 original articles and 5 reviews, for the in-depth analysis. As a result, the organic Rankine cycle was identified as the most common technique for waste heat recovery. Cold energy recovery was found to be an innovative strategy but limited to vessels with LNG facilities. Despite the low representation in scientific literature, thermoelectric generators appeared to be a promising direction for future research. The recovery of low-grade waste heat was identified as a promising gap on the knowledge.