Veronika Dornburg

Efficiency and economy of wood-fired biomass energy systems in relation to scale regarding heat and power generation using combustion and gasification technologies

Policy objectives to increase biomass’ contribution to the energy supply in industrialised countries are quite ambitious, but biomass resources are rather limited and expensive in many situations. Therefore, an optimal utilisation of resources producing a maximum of energy at minimal costs is desirable. A wide variety of biomass conversion options with different performance characteristics exists. Also, the economic and energetic performance depends on many variables, such as costs of logistics, scaling effects and degree of heat utilisation to name a few. Therefore, system analysis is needed to identify optimal systems. In this study, different biomass energy systems are analysed regarding their energetic and economic performance related to fossil primary energy savings. The systems studied contain residual woody biomass, logistics, heat distribution and combustion or gasification units producing heat, power or CHP. The performance of systems is expressed as a function of scale. This is done by applying generic functions to describe plants’ efficiencies and specific investment costs and by expressing costs and energy use of logistic and heat distribution as a function of conversion unit capacities. Scale effects within biomass energy systems are significant. Up-scaling increases the relative primary energy savings of the studied systems within the scale range of 0– regarded, while costs per unit of primary energy savings decrease or have an optimum at medium scales. The relative primary energy savings lay between 0.53 and . With costs of 4– systems are not profitable under Dutch conditions with residual wood prices of while firing waste wood with zero costs at the plant gate renders profitable operation possible. Favourable in both economic and energy terms are BIG/CC plants.

Comparing the land requirements, energy savings, and greenhouse gas emissions reduction of biobased polymers and bioenergy: an analysis and system extension of life-cycle assessment studies.

This study compares energy savings and greenhouse gas (GHG) emission reductions of biobased polymers with those of bioenergy on a per unit of agricultural land-use basis by extending existing life-cycle assessment (LCA) studies. In view of policy goals to increase the energy supply from biomass and current efforts to produce biobased polymers in bulk, the amount of available land for the production of nonfood crops could become a limitation. Hence, given the prominence of energy and greenhouse issues in current environmental policy, it is desirable to include land demand in the comparison of different biomass options. Over the past few years, numerous LCA studies have been prepared for different types of biobased polymers, but only a few of these studies address the aspect of land use. This comparison shows that referring energy savings and GHG emission reduction of biobased polymers to a unit of agricultural land, instead of to a unit of polymer produced, leads to a different ranking of options. If land use is chosen as the basis of comparison, natural fiber composites and thermoplastic starch score better than bioenergy production from energy crops, whereas polylactides score comparably well and polyhydroxyalkaonates score worse. Additionally, including the use of agricultural residues for energy purposes improves the environmental performance of biobased polymers significantly. Moreover, it is very likely that higher production efficiencies will be achieved for biobased polymers in the medium term. Biobased polymers thus offer interesting opportunities to reduce the utilization of nonrenewable energy and to contribute to GHG mitigation in view of potentially scarce land resources.

The global technical and economic potential of bioenergy from salt-affected soils

This study assesses the extent and location of salt-affected soils worldwide and their current land use and cover as well as the current technical and economic potential of biomass production from forestry plantations on these soils (biosaline forestry). The global extent of salt-affected land amounts to approximately 1.1 Gha, of which 14% is classified as forest, wetlands or (inter)nationally protected areas and is considered unavailable for biomass production because of sustainability concerns. For the remaining salt-affected area, this study finds an average biomass yield of 3.1 oven dry ton ha−1 y−1 and a global technical potential of 56 EJ y−1 (equivalent to 11% of current global primary energy consumption). If agricultural land is also considered unavailable because of sustainability concerns, the technical potential decreases to 42 EJ y−1. The global economic potential of biosaline forestry at production costs of 2€ GJ−1 or less is calculated to be 21 EJ y−1 when including agricultural land and 12 EJ y−1 when excluding agricultural land. At production costs of up to 5€ GJ−1, the global economic potential increases to 53 EJ y−1 when including agricultural land and to 39 EJ y−1 when excluding agricultural land. Biosaline forestry may contribute significantly to energy supply in certain regions, e.g., Africa. Biosaline forestry has numerous additional benefits such as the potential to improve soil, generate income from previously low-productive or unproductive land, and soil carbon sequestration. These are important additional reasons for investigating and investing in biosaline forestry.