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

•Bibliometric analysis of literature on waste heat recovery from marine engines is presented. Patterns in keywords, year of publication and country of origin are analyzed.•Systematic review of high impact articles comparing waste heat recovery technologies is conducted.•Classical waste heat sources from marine engines are reviewed and complemented by new studies on the recovery of heat radiated from the block.•Organic Rankine cycles are identified as the most versatile waste heat recovery technology, being able to recover different grades of heat.•Maximization of energy recovery is only possible by combining several systems, optimized to recover different grades of thermal energy.