Optimising Bioenergy Use in District Heating Systems in the EU

  • Rowan Green

Student thesis: Masters ThesisMEng


Bioenergy, energy derived from organic material originating from plants, microbial cells and the waste and residues associated with their processing, accounts for the largest renewable share of final energy consumption (FEC) in the European Union (EU). Its contribution is only likely to increase as global movements to tackle the current climate emergency continue. The issue of climate change is not only addressed in global treaties, such as the 1977 Kyoto Protocol and the 2015 Paris Agreement but is also gaining traction with a new generation as young people across the world strike to bring attention to the need for action.
This report focuses on biomass powered district heating systems and optimising their use within the EU. Existing literature is examined to see how bioenergy systems have been analysed and highlights the importance of regarding both feedstock type and conversion technology in parallel for a thorough optimisation. Various optimisation methods are explored and a mathematical multi-criteria optimisation (MCO) is performed considering both environmental and economic performance. Two equations are investigated to explore the sensitivity of output to the objective function and the potential of changing this to suit different stakeholders is discussed. The BioGrace II tool is used to calculate greenhouse gas (GHG) emissions and emission reduction potential for 310 scenarios, across four countries. These are then ranked based on their potential for emission reduction and by their performance in the MCO which aims to minimise the output value. All scenarios offer emission reductions when compared to fossil fuel counterparts with values ranging from 11% to over 100%. The optimal biomass pathway is identified as the anaerobic digestion (AD) of manure in Spain, Germany and Poland to produce biogas with values of 0.26, 0.62 and 0.72 respectively. In Finland the optimum solution is the use of forest residue chips for CHP systems when replacing peat or coal achieving an optimisation value of 6.4, however combustion scenarios in Spain (straw) and Poland (forest residues) perform better than this at 3.1 and 3.4 respectively. A major limitation of this analysis stems from the inclusion of emission credits in the BioGrace tool due to improved manure management. This results in negative net total equivalent emissions for these pathways and reduction percentages over 100% which were difficult to analyse. To overcome this constraints were imposed which meant many AD process outputted the same optimisation value despite differences in transportation output or alternative fuel which was considered in the discussion.
Date of Award30 Apr 2019
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorMarcelle McManus (Supervisor) & Oliver Pountney (Supervisor)

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