The role of plasma in syngas tar cracking

Gasification of biomass and municipal solid waste is a technology that has been proposed as a dual-purpose solution for mitigating environmental impacts as well as for producing syngas, a very useful intermediary product for energy valorization and organic synthesis. However, the presence of pollutants, notably tar, hampers this raw syngas (producer syngas) to be used in high-efficient energy applications such as jet engines and fuel cells or in Fischer-Tropsch synthesis, limiting its economic value. For reducing tar, a lot of scientific and technical effort has been devoted. In this paper, the state of the art of plasma tar removal from syngas is done, focusing on the use of plasma in tandem with existing technologies, underlining its advantages and the remaining challenges. The most promising ways to get a syngas with very low tar levels using plasma seem to be (i) tandem tar cleaning techniques (e.g. secondary plasma enhanced catalytic unit) and (ii) secondary thermal plasma cracking units.