Optimization of the Value Chain of the Existing Free Potentials of Wood Resources for Power Generation in Baden-Württemberg
Karlsruhe Institute of Technology
Javier Parrilla-Martínez hat Physik an der Universität Zaragoza studiert und sich dabei auf Biomasse und Biobrennstoffe spezialisiert. Anschließend führte er als Projektleiter in der Wirtschaft Studien zur Wärme-, Strom- und Kraftstofferzeugung aus Pflanzenölen durch.
Es folgten Anstellungen als Stipendiat an der Universität Cottbus mit der Ausrichtung auf Logistikansätze für holzartige Biomasse und als akademischer Mitarbeiter an der Universität Karlsruhe (KIT). Am KIT beschäftigte er sich mit der Durchführung von Energiesystemanalysen und der Entwicklung der Software BIOSPHERE, die die Wertschöpfungsketten biogener Rohstoffe optimiert.
Javier Parrilla-Martínez promovierte im Oktober 2018.
optimization, model, profitability, restriction, value chain, bioenergy, wood resources, power, heat, utlilisation pathway, location allocation, fluidised-bed gasification, gas engine, BIGCC, co-firing, harvesting, densification, chipping, transport
The energy mix of Baden-Württemberg – one of the most wooded regions of Germany – could be diversified through the optimal valorisation of the existing free potentials of wood resources. Circa 17 PJ of forest residues and landscape wood raw material grow annually over the territory of this federal state. For this reason, an optimisation of the corresponding value chain for power purposes is accomplished in order to identify the most cost-efficient utilisation pathways. Firstly, each unexploited potential of wood resources for up to ten different types of wood chips is estimated at district level. Next, the stages of felling, extraction, debranching, moving and chipping of wood resources are modelled into four specific logistic chains on the basis of the size of forest ownership, the steepness of slope and the variety of tree. Moreover, specific unit costs based on different cost allocation procedures are assigned to the ten identified types of chipped wood resources. Besides the modelling of the transport sector, an array of all feasible technologies for conversion of wood resources into bio-based power are compared to each other in terms of costs. A singular conclusion is drawn according to which, for each particular capacity under the same operation conditions, gasification is more cost-efficient than combustion – except for co-firing. Hence, the fluidised bed gasification coupled to a gas engine or a combined cycle as well as the direct co-firing of wood resources at a 10% co-fire rate are preselected for the intended analysis on account of their higher cost-effectiveness. Lastly, a new MILP model called BIOSPHERE (Bioenergy Optimisation Software for Production Pathways at High Energy and Resource Efficiency) is created for the optimisation of the value chain of wood resources. This optimising tool includes a unique mathematical constraint aiming at assuring profitability of investments within each utilisation pathway.
A scenario-based analysis is first developed for remunerations modelled with a high enough value above the breakeven point. Thereby, a combined heat and power cogeneration process consisting of a fluidised bed gasifier coupled to a gas engine of 20 MWe renders electricity production costs of 10.1-13.8 €cent/kWhe for an annual amount of 7,500 full load hours. The co-firing option for the existing coal-fired power plants with bio-based capacities up to 84.3 MWe generates lower electricity production costs of 6.6-11.7 €cent/kWhe, when the facilities are yearly operated for 3,000 full load hours. If a fluidised bed gasifier is connected to a combined cycle of 210/340 MWe (7,500 full load hours per year), this technology turns out to be the most cost-efficient with electricity production costs in the order of 5.6-7.1 €cent/kWhe. These costs ranges can be reduced by progressively decreasing remunerations below each resulting breakeven point. As for the option of co-firing, cheaper bioenergy configurations arise on the basis of cheaper wood resources that enable lower production costs of up to 5.6 €cent/kWhe for 4,000 hours per year at full load. In conclusion, the low incremental capital costs of co-firing as well as the high efficiencies of fluidised bed gasification-based combined cycles together with the valorisation of the more economical deciduous fractions of wood resources might reduce electricity production costs to a rather low range between 4.5 and 9.5 €cent/kWhe. Leveraging such cost reductions, the introduction of appropriate energy policy instruments for the promotion of carbon-neutral baseload power generation is strongly recommended in view of restrictions induced by Germany’s nuclear and coal phase-outs. Although the quality of the results of this study is mainly conditioned by uncertainty and the high spatial aggregation level of the spatial unit, the implemented methodology as well as the performed optimisation analysis represents an interesting breakthrough that may contribute to the initiated energy transition in Baden-Württemberg and the whole of Germany.
■doi: 10.5445/IR/1000099390/v2 coisas