Energy from biomass and the use of small direct fired gas turbine systems

This paper discusses the context for the use of biomass for electricity generation in the UK and similar markets and evaluates the possibility of using cyclonic gasification coupled to small gas turbine systems. In the UK the Government has strongly pushed for a significant increase in the use of renewable energy for electricity generation with only very modest success, nearly 3% coming from this source at present, predominantly hydro and wind. Subsidy for the early tranches of these systems came from an elevated price for generated electricity, but since attempts at price convergence with that pertaining with conventional fossil fuel generation systems has occurred the number of biomass systems being constructed and their net generating capacity has not increased in line with other technologies. Although utilisation technologies exist, and are well proven technologically in Scandinavia, when translated to markets such as the UK, give generating costs which are not competitive with other forms of renewable energy. Problems have arisen with many systems, being predominantly due to fouling/slagging, the different nature of the fuels, and elevated moisture content.\ud In this context this paper describes an EU sponsored programme of work to develop a simple cyclone gasifier and combustor which can produce a medium calorific fuel gas for materials such as sawdust, retain up to about 80% of the total ash/residues in the system, and fire simple, low cost gas turbines for power generation. The system is shown to have a very wide operating range and can handle sawdust with significant quantities of material up to 4mm in size, whilst tolerating significant variation in moisture content and capturing very significant quantities of the ash/particulate matter as well as volatile species.