Fundamental designs of gasification plants for combined heat and power

Biomass gasification is a commonly used thermochemical process from which a wide diversity of commodities can be generated. Meanwhile, biomass gasification, producer gas cleaning, and heat and power generation present several technology constraints. Therefore, to endorse the exploitation of biomass gasification, innovative design concepts are required which must overcome or minimize the technological constraints. These concepts must deal with the producer gas quality optimization, maximize the yields, increase the process efficiency, and improve the economic viability. The objective of this review is to assess conventional and innovative biomass gasification technologies for combined heat and power production, characterizing the current state of the art of the technology. The most well-proven and widely acknowledged single cycle and combined cycle gasification plants are reviewed. Depending on the gas application, weaknesses and strengths are seen for different systems, tar and gas cleaning being among the most influencing parameters. The main conclusion that can be drawn is about the different successful technical concepts that can be employed both in a single cycle and combined cycle power production, using different gasification reactors combined with the appropriated gas cleaning and conditioning systems, and using either gas engines or gas turbines with approximately the same degree of success. However, the performed survey also exposed the unsuccessful economic concept of biomass-based gasification power production that delays its commercial exploitation. Future directions for biomass gasification should be focused on its economic viability through small-scale demonstration gasification plants integrating advanced concepts tending to reduce the operational costs.