The gasification technologies using blends of coal and waste/biomass were investigated aiming to examine their potential application in Greece. Following, a feasibility study for the installation of an IGCC system that exploits Greek brown coal with RDF in Western Macedonia, Greece was carried out. Among others, IGCC systems offer several benefits, such as the flexibility of fuel supply, the environmental friendly plant operation and the commercial application of the process by-products, such as the gasification slag and the elemental sulphur from the desulphurisation unit.
Co-gasification of coal and waste can be performed with direct or indirect gasification. Both technology concepts are now demonstrated and they seem to be the most promising energy exploitation options for solid fuels, especially residues. Since there are sufficient lignite deposits in W. Macedonia and an integrated system of Municipal Solid Waste (MSW) treatment already exists, the specific region was selected in order to examine the possibility of an IGCC system application. The gasifier is based on the British Gas Lurgi (BGL) technology, the gasification agent being steam and oxygen, producing a synthetic gas rich in CO, H2 and CH4. Taking into account the total annual production of MSW in W. Macedonia, the maximum capacity of the unit was estimated up to 30 MWe. The investment cost at this capacity range is much higher and almost tripled compared to the reference case of brown coal, despite the lower fuel supply cost. This is also valid for the operation cost, which is higher than the electricity sales price in Greece, on kWhe basis. The high investment cost of IGCC systems using coal/RDF blends, within the capacity range of 30-200 MWe, implies the modular construction of the unit near operating power plants. First, the gasifier is installed and the produced syn-gas is then supplied in an operating lignite-fired unit. The plant turns into a direct gasification application, when the flue gas treatment equipment and the power generation system are installed.
Keywords: IGCC, BGL gasifier, feasibility study, Municipal Solid Waste, slag.