Comparative studies of environmental regulations in connection with combustive energy production

The study of environmental regulations for energy production, specifically related to stack gas emission from combustion plants, was undertaken in order to investigate to what degree existing provisions were fuel neutral. 'Fuel' is here taken to mean a material whose combustion is used to supply heat for any purpose. The report consists of three parts, viz., 1. Environmental regulations for energy production in combustion plants. Presented data refer mainly to Sweden, Germany, France, Switzerland, and The European Union, but some data from Belgium, Denmark, Italy, The Netherlands, and Spain are also given. A dividing line between conventional fuels (coal, wood, oil, etc) and waste fuel (that is municipal solid waste, MSW) becomes apparent. As a rule, requirements for the former comprise particulates, sulphur oxides, nitrogen oxides, and carbon monoxide only, while requirements for dioxins, mercury and other heavy metals befall MSW only. In Germany, substances common to both fuel categories are subjected to stricter regulations if they occur in MSW, while no pronounced discrimination - except for particulates - is discernible in Sweden. France has emission limits for MSW as far as carbon monoxide and hydrogen halides are concerned, but none for conventional fuels. The EU directive for large combustion plants sets requirements for particulates and sulphur oxides for MSW combustion, but not for plants of comparative size (<50 MW) designed for conventional fuels. In order to enable comparison between different kinds of fuel, all limit values have been recalculated to the 'natural' reference point of 0 % O2, i.e., unit air factor (λ = 1). 2. Heat and power plant data and their treatment. This section contains case studies of three fluidized-bed plants, one with a stationary bed burning MSW, and two circulating beds fired with conventional solid fuels, and chipped wood waste in combination with packaging manufacturing loss consisting of polyethylene coated cardboard, respectively. Current reporting of this kind of data was found to be rather inconsistent and its proper treatment requires an unreasonable amount of time and effort. It is therefore proposed that a standardisation project will be undertaken for the purpose of harmonizing the reporting scheme. The resulting clarity and coherence will not only save time and efforts but should also lead to more environmentally efficient measures in the long run. 3. How to specify pollutant concentration in flue and stack gas. This part elucidates at some length the fundamental mathematical chemistry that is required for correct calculations of pollutant concentrations in flue and stack gas. Equations are derived for calculation of the maximum pollutant concentration in the flue gas, and for re-calculation of stack gas concentration values from one reference point (e.g., 13 % CO2) to another (e.g., 0 % O2). The pollutant concentration in the fuel has to be known. The actual flue gas concentration value can be considerably lower than the calculated maximum value. This is the case if a part of the pollutant ends up in slag and bottom ash. If flue gas cleaning is employed, the stack gas concentrations may be still further from the calculated maximum value