Optimization of the Value Chain of the Existing Free Potentials of Wood Resources for Power Generation in Baden-Württemberg

Karlsruhe Institute of Technology

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Javier Parrilla-Martínez

Javier Parrilla-Martínez studied Physics at the University of Zaragoza and specialised in biomass as well as biomass fuels. Having finished his studies, he worked as a project manager and led studies on the production of heat, power, and fuel from plant oils.
He held a scholarship from the Brandenburg University of Technology, where he focused on logistic solutions for wooden biomass before he was employed at the Karlsruhe Institute of Technology (KIT). There he analysed energy systems and developed the software BIOSPHERE that optimises the value chains of biogenic resources.
Javier Parrilla-Martínez received his doctorate in October 2018.

Let's have a?

Expertise

  • Bioenergy know-how in harvesting, densification, transport and conversion of wood resources
  • Analysis of energy systems (PERSEUS, TIMES, BIOSPHERE)
  • Modelling of virtual flows

Of interest to

  • Public authorities fostering new infrastructures for sustainable power generation
  • Suppliers and investors in the bioenergy sector
  • Everyone interested in intelligent power networks
Unsplash/Ashes Sitoula
Javier Parrilla-Martínez

Javier Parrilla-Martínez studied Physics at the University of Zaragoza and specialised in biomass as well as biomass fuels. Having finished his studies, he worked as a project manager and led studies on the production of heat, power, and fuel from plant oils.
He held a scholarship from the Brandenburg University of Technology, where he focused on logistic solutions for wooden biomass before he was employed at the Karlsruhe Institute of Technology (KIT). There he analysed energy systems and developed the software BIOSPHERE that optimises the value chains of biogenic resources.
Javier Parrilla-Martínez received his doctorate in October 2018.

Let's have a?

Expertise

  • Bioenergy know-how in harvesting, densification, transport and conversion of wood resources
  • Analysis of energy systems (PERSEUS, TIMES, BIOSPHERE)
  • Modelling of virtual flows

Of interest to

  • Public authorities fostering new infrastructures for sustainable power generation
  • Suppliers and investors in the bioenergy sector
  • Everyone interested in intelligent power networks

Interview

Arthur Höring
Editor

Your dissertation deals with the potential of wood. How is this potential defined, and in what ways can it be used?

Javier Parrilla-Martínez
is typing…
Arthur Höring
Redakteur

Your dissertation deals with the potential of wood. How is this potential defined, and in what ways can it be used?

Javier Parrilla-Martínez
Doktorand

Of all existing wood resources, such as forest residues, landscape wood raw material, woody green wastes, wood wastes and industrial wood residues, only the first two types currently have unexploited potentials that could be tapped. Forest residues are a waste product obtained from logging activities in forest areas with the aim of producing wood as a feedstock. Landscape wood raw material, on the contrary, is not a residue but an actually unconsumed natural resource that can be gained from trees and shrubs in wooded formations such as copses and groves.
The energy use of wood resources can occur in the form of heat, power or biofuels. My work, however, is only concerned with power generation because new base load power plants are urgently needed due to the progressive nuclear and coal phaseouts.
To generate power, this wood potential could be exploited according to either a decentralised or centralised approach, depending on which of the more cost-efficient conversion technologies is implemented. These would include the use of fluidised bed gasifiers, which can generate a maximum of 20 electrical megawatts (MWe) when connected to a gas engine, or a power capacity of at least 200 MWe if coupled to a combined cycle.

Arthur Höring
Redakteur

You developed a software for your research that is designed to optimise the value chain of wood resources. Which reference points does the software use to accomplish that?

Javier Parrilla-Martínez
Doktorand

The BIOSPHERE software enables decisions to be made on which actors and/or processes should be used to transform material or energy resources into new products. This energy and material flow model optimises the targeted system by minimising the total expenditures. Besides, BIOSPHERE contains a mathematical restriction for any feasible utilisation pathway—consisting of a supply chain and a conversion plant—to ensure its profitability. This will avoid uneconomical investments for plant operators and/or investors.
In order to implement this novel methodological approach, a number of equation systems with an array of new variables are required. These variables are the virtual flows and stand for the smallest indivisible energy and material flows that sequentially connect all possible successive processes within a utilisation pathway. In addition to the amount of energy, they also show a breakdown of the real energy flows into their essential components. This means that the virtual flows determine exactly what actors (processes) produce, transform and finally consume energy in the analysed system. In this respect, they will be extremely important, for example in the management of intelligent networks.

Arthur Höring
Redakteur

By now, sustainable energy is a public issue with high social relevance. How would you evaluate the findings of your dissertation in relation to that topic?

Javier Parrilla-Martínez
Doktorand

In terms of greenhouse gas levels, the mere generation of power from wood resources is a sustainable process. Firstly, as it consists in the thermal conversion of a carbon-neutral combustible. This means that as much carbon dioxide from combustion is emitted into the atmosphere as the trees absorb from air for their growth. Secondly, the formation of nitrogen oxides is reduced to a minimum thanks to the low operating temperatures occurring in fluidised bed systems. This minimum can, however, be cost-effectively removed by using suitable gas cleaning techniques—especially in large power plants.
Other pollutant emissions such as particulate matter, ash or soot arise to a smaller extent, but they should equally be eliminated or reduced.
It would also be important to lessen emissions along the entire supply chain from harvesting via densification to transport—possibly even by means of its electrification, especially for machinery and vehicles.
Ultimately, the unexploited potential of wood resources in Baden-Württemberg could account for up to 4% of its gross electricity consumption on a truly climate-neutral basis.

Keywords

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

Summary

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.

Suggested citation

Parrilla-Martínez, Javier. Optimization of the Value Chain of the Existing Free Potentials of Wood Resources for Power Generation in Baden-Württemberg. Karlsruher Institut für Technologie, 2019, http://dx.doi.org/10.5445/IR/1000099390/v2.

Repository

publikationen.bibliothek.kit.edu

Identifiers

urn: urn:nbn:de:101:1-2019121104590094536027

doi: 10.5445/IR/1000099390/v2

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