Membrane distillation (MD) lags behind other desalination processes such as reverse osmosis due to relatively high energy consumption. Heating in membrane distillation forms a significant component of total energy consumption. This review provides an overview of the various conventional and non-conventional heating methods used in the MD process, focusing on its application for water desalination. To make MD competitive with existing technologies, research should be directed at low-cost energy sources or alternative heating methods. Development of alternative heating methods is based on the direct heating of feed water where the driving force for distillation can be generated inside the membrane module, as is the case for photothermal heating, electrothermal heating or induction heating. Direct heating of the feed near the membrane surface can improve the thermal efficiency and economics of the MD process. Through this literature survey, we have identified some areas to guide future research in alternative heating techniques for membrane distillation.