Design and optimization of flexible multi-generation systems

Christoffer Ernst Lythcke-Jørgensen

Research output: Book/ReportPh.D. thesisResearch

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This thesis focuses on the design of flexible multi-generation systems, which are dynamic and integrated energy conversion systems characterized by the ability to adjust operation in response to fluctuating operating conditions. It is the hypothesis that these systems may support the balancing of variable renewable energy sources in a cost-effective way by linking the different sectors in the energy system with local energy supply systems.
A key challenge faced in the development of flexible multi-generation system is the knowledge gap between process design practices, which simplify energy system variations and dynamics, and energy system analysis, which fails to consider process integration synergies in local systems. The primary objective of the thesis is to derive a methodology for linking process design practices with energy system analysis for enabling coherent and holistic design optimization of flexible multi-generation systems.
A methodology is presented for optimizing the design of flexible multi-generation systems which considers: Selection, dimensioning, location and integration of processes; operation optimization with respect to both hourly variations in operating conditions as well as long term energy system development; biomass supply chains and local resource availability; combined with global sensitivity and uncertainty analysis. The methodology includes a novel method for aggregating external operating condition datasets, named the CHOP method. In addition, three case studies focusing on integrating biomass processing and energy conversion technologies in existing combined heat and power plants in Denmark are conducted using the developed methods.
The outcomes of this thesis indicate that the developed design methodology is efficient in screening for promising designs of flexible multi-generation system. In addition, the case study results emphasize the importance of considering flexible operation, systematic process integration, and systematic assessment of uncertainties in the design optimization. It is recommended that future research focus on assessing system impacts from flexible multi-generation systems and performance improvements from storage options.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages298
ISBN (Electronic)9788774754749
Publication statusPublished - 2016
SeriesDCAMM Special Report


  • Biomass conversion
  • Design optimization
  • Energy conversion
  • Flexible multi-generation
  • Operation optimization
  • Polygeneration
  • Process integration
  • Smart energy


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