In water management, wastewater treatment plants are characterised both as energy consumers and producers. When considering future energy supply systems, the focus is increasingly on the utilisation or storage of (surplus) energy in addition to conventional electrical energy supply. Independent of many development and optimisation efforts of available components, a special need is detected in the networking of the entire energetic infrastructure, the interaction of individual components and the provision of regenerative energy sources. In this context, wastewater treatment plants offer favourable conditions and special synergy effects for the interconnection of different technologies.
FiW began investigating alternative concepts for energy storage in 2010 within the framework of the project "Use of Hydrogen Technology in Wastewater Disposal" (WaStrak) funded by the NRW Environment Ministry.
This has resulted in a pilot plant in which the sewage gas is further utilised via steam reforming and catalytic reaction to produce methanol, a higher-value liquid energy carrier. By means of this project, the feasibility of this recycling approach on a pilot scale was demonstrated. Based on the results obtained in the WASTRAK project, FiW is working together with OWI on the optimisation of the synthesis plant and thus on the elaboration of a plant concept ready for marketing.
The research on the existing plant relates to several key issues:
- Development of an extended reforming process for biogas
- Integration of an electrolyser
- Extension of the synthesis process by one distillation stage
- Improvement of the synthesis reactors
- Optimisation of the process and process parameters
All in all, the individual optimisations are aimed at producing high-purity methanol with the demonstrator. This represents an alternative, high-quality use of sewage and biogas, which provides an economical alternative to the use of the gas in a combined heat and power station. In addition, a closed plant concept is to be developed which allows an ecological scaling of the plant size and thus has the potential to be marketed to producers of digester gas in the future.
Customer: Federal Ministry of Economics and Energy
Project owner: EURONORM GmbH
Project partner: OWI Science for Fuels gGmbH