Optimising waste treatment systems: Part A: Methodology and technological data for optimising energy production and economic performance

The treatment and utilisation of biomass residues and waste for energy and recycling can contribute significantly to greenhouse gas emission reduction. Therefore, a waste treatment structure should be designed for an efficient saving of fossil primary energy in terms of maximal primary energy savings or minimal costs per unit of primary energy savings. However, this is a complex task, given the large number of technologies, recycling options and their logistic consequences, that necessitate an integrated analysis. Also, on longer term various new and improved technologies become available which can affect performances for options from an economic and/or energy point of view. For that reason, an optimisation tool, that optimises a biomass and waste treatment system for a given amount of biomass and waste, is developed in this study. This optimal biomass and waste treatment system is composed of several treatment installations, that are characterised by scale, location and kind of technology. Important aspects that are taken into account in the analysis are heat distribution, biomass and waste transport and economies of scale. A broad variety of technologies for material recycling, conversion of biomass and/or waste to heat, electricity or transportation fuel are included in the optimisation tool. Performance data of these technologies are based on an extensive review. Examples of included technologies comprise: integrated gasification with combined cycle, waste incineration, pyrolysis, digestion, co-firing in fossil power plants, biomass incineration, hydro-thermal upgrading, paper recycling and chipboard production. A comparison of the different technologies in relation to scale shows that primary energy savings and costs per unit of primary energy savings diverge significantly. In general, the optimisation tool developed here is suitable for analyses of optimal biomass and waste treatment structures in different regions with regard to primary energy savings and their costs. By means of scenario analysis, robust optimal solutions in terms of primary energy savings and their costs can be identified and the influence of important parameters can be analysed. A case study of the Dutch biomass and waste treatment systems has been carried out with the optimisation tool and is presented in part two of this article.