During the opening of the Hanze Energy Transition Centre or EnTranCe posters were on display for the King and for the public. These posters where accompanied by the researchers to explain their research in more detail if questions did arise.
The energy efficiency and sustainability of an anaerobic green gas production pathway was evaluated, taking into account five biomass feedstocks, optimization of the green gas production pathway, replacement of current waste management pathways by mitigation, and transport of the feedstocks. Sustainability is expressed by three main factors: efficiency in (Process) Energy Returned On Invested (P)EROI, carbon footprint in Global Warming Potential GWP(100), and environmental impact in EcoPoints. The green gas production pathway operates on a mass fraction of 50% feedstock with 50% manure. The sustainability of the analyzed feedstocks differs substantially, favoring biomass waste flows over, the specially cultivated energy crop, maize. The use of optimization, in the shape of internal energy production, green gas powered trucks, and mitigation can significantly improve the sustainability for all feedstocks, but favors waste materials. Results indicate a possible improvement from an average (P)EROI for all feedstocks of 2.3 up to an average of 7.0 GJ/GJ. The carbon footprint can potentially be reduced from an average of 40 down to 18 kgCO2eq/GJ. The environmental impact can potentially be reduced from an average of 5.6 down to 1.8 Pt/GJ. Internal energy production proved to be the most effective optimization. However, the use of optimization aforementioned will result in les green gas injected into the gas grid as it is partially consumed internally. Overall, the feedstock straw was the most energy efficient, where the feedstock harvest remains proved to be the most environmentally sustainable. Furthermore, transport distances of all feedstocks should not exceed 150 km or emissions and environmental impacts will surpass those of natural gas, used as a reference. Using green gas as a fuel can increase the acceptable transportation range to over 300 km. Within the context aforementioned and from an energy efficiency and sustainable point of view, the anaerobic digestion process should be utilized for processing locally available waste feedstocks with the added advantage of producing energy, which should first be used internally for powering the green gas production process.
A transparent and comparable understanding of the energy efficiency, carbon footprint, and environmental impacts of renewable resources are required in the decision making and planning process towards a more sustainable energy system. Therefore, a new approach is proposed for measuring the environmental sustainability of anaerobic digestion green gas production pathways. The approach is based on the industrial metabolism concept, and is expanded with three known methods. First, the Material Flow Analysis method is used to simulate the decentralized energy system. Second, the Material and Energy Flow Analysis method is used to determine the direct energy and material requirements. Finally, Life Cycle Analysis is used to calculate the indirect material and energy requirements, including the embodied energy of the components and required maintenance. Complexity will be handled through a modular approach, which allows for the simplification of the green gas production pathway while also allowing for easy modification in order to determine the environmental impacts for specific conditions and scenarios. Temporal dynamics will be introduced in the approach through the use of hourly intervals and yearly scenarios. The environmental sustainability of green gas production is expressed in (Process) Energy Returned on Energy Invested, Carbon Footprint, and EcoPoints. The proposed approach within this article can be used for generating and identifying sustainable solutions. By demanding a clear and structured Material and Energy Flow Analysis of the production pathway and clear expression for energy efficiency and environmental sustainability the analysis or model can become more transparent and therefore easier to interpret and compare. Hence, a clear ruler and measuring technique can aid in the decision making and planning process towards a more sustainable energy system.
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A major challenge for the Netherlands is its transition to a sustainable society: no more natural gas from Groningen to prevent earthquakes, markedly reduced emissions of the greenhouse gas carbon dioxide to stop and invert climate change, on top of growth of electricity in society. Green gas, i.e. biogas suitable for the Dutch gas grid, is supposed to play a major role in the future energy transition, provided sufficient green gas is produced. This challenge has been identified as urgent by professional, academic and private parties and has shaped this project. In view of the anticipated pressure on biomass (availability, alternative uses), the green gas yield from difficult-to-convert biomass by anaerobic digestion should be improved. As typically abundant and difficult-to-convert biomass, grass from road verges and nature conservation areas has been selected. Better conversion of grass will be established with the innovative use of new consortia of (rumen) micro-organisms that are adapted or adaptable to grass degradation. Three-fold yield increase is expected. This is combined with innovative inclusion of oxygen in the digestion process. Next green hydrogen is used to convert carbon dioxide from digestion and maximize gas yield. Appropriate bioreactors increasing the overall methane production rate will be designed and evaluated. In addition, new business models for the two biogas technologies are actively developed. This all will contribute to the development of an appropriate infrastructure for a key topic in Groningen research and education. The research will help developing an appropriate research culture integrated with at least five different curricula at BSc and MSc level, involving six professors and one PhD student. The consortium combines three knowledge institutes, one large company, three SMEs active in biogas areas and one public body. All commit to more efficient conversion of difficult-to-convert biomass in the solid body of applied research proposed here.
