Value Chain Optimisation of Biogas Production

With an increased focus on climate change and an increasing number of unpredictable and fluctuating renewable energy sources, a predictable renewable energy carrier is needed to stabilise energy production. Biogas can potentially be used for this but biogas projects struggle with becoming economically feasible.

In this PhD thesis, the focus is to create models for investigating the profitability of biogas projects by: 1) including the whole value chain in a mathematical model and considering mass and energy changes on the upstream part of the chain; and 2) including profit allocation in a value chain consisting of heterogeneous owners.

To address the first point, a mathematical model based on network-flow optimisation has been developed to include the mass and energy losses in the chain. Furthermore, a method for simplifying the calculation of transportation costs has been included. Last, the costs on the biogas plant has been included in the model using economy of scale.

For the second point, a mathematical model considering profit allocation was developed applying three allocation mechanisms. This mathematical model can be applied as a second step after the value chain optimisation. After concentrating on how to make biogas economically feasible, the use of biogas in the energy system is considered by applying the energy systems model Balmorel and: 1) increasing the cost of CO2 to reach a combined goal of biogas and biomethane; and 2) including the production of renewable gas and fuels in the energy systems model to find the optimal end use of each type of gas and fuel.

The main contributions of this thesis are the methods developed on plant level. Both the mathematical model for the value chain and the profit allocation model can be generalised and used in other industries where mass and value of the goods in the chain changes independently from each other and where several heterogeneous owners interact to make the value chain work.

This could be other bioenergy projects as well as e.g. a value chain for clothing or cars.