Biomass co-firing - an efficient way to reduce greenhouse gas emissions

In an optimal situation, co-combustion of biofuel with fossil fuels derivs benefits from both fuel types and also some extra advantages. These could be e.g. the reactions between different chemical elements originating from biofuel and fossil fuel. This publication provides information on biomass characteristics, fuel handling and pre-treatments, different types of co-combustion technologies, the challenges of co-combustion sets to boiler operations, emissions and research and testing. A short description on the following biofuels is included: straw, wood fuels, recycled fuels and olive oil production residues. Some case examples of axisting co-combustion plants are given

Co-combustion of coal and olive oil industry residues in fluidised bed

Recently new environmental regulations of fossil fuels have further increased interest in the use of waste and biomass for energy generation. Co-combustion is generally viewed as the most cost-effective approach to biomass and wastes utilisation by the electric utility industry.The aim of this paper is to assess the feasibility of co-firing coal and a very specific biomass waste from the olive oil industry: foot cake, in a fluidised bed. This waste is quite difficult material to be used in combustion process, due to its high moisture content and alkaline content in ashes.Two different Spanish coals were selected for this study: a lignite and an anthracite. The combustion tests were carried out in the CIEMAT bubbling fluidised bed pilot plant. In order to study the effect of different parameters on the emissions and combustion efficiency, the tests were done using different operating conditions: furnace temperature, share of foot cake in the mixtures and coal type.The pilot plant tests show that the combustion of foot cake/lignite or anthracite mixtures in bubbling fluidised bed is one way to utilise this biomass residue in energy generation. The presence of foot cake in the mixtures has not any significant effect on the combustion efficiency. SO2 and NOx emissions decrease when the amount of foot cake in the mixtures increases, while N2O emission increases.<br/