In het hoofdstuk wordt ingegaan op de innovaties in de Europese gassector, met een speciale focus op de invoeding van groen gas (ook wel biomethaan) in het aardgassysteem. Er wordt een algemeen juridisch kader geschetst en er vindt een rechtsvergelijking plaats van de nationale rechtsordes aangaande Duitsland, Denemarken en Nederland.
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Wind and solar power generation will continue to grow in the energy supply of the future, but its inherent variability (intermittency) requires appropriate energy systems for storing and using power. Storage of possibly temporary excess of power as methane from hydrogen gas and carbon dioxide is a promising option. With electrolysis hydrogen gas can be generated from (renewable) power. The combination of such hydrogen with carbon dioxide results in the energy carrier methane that can be handled well and may may serve as carbon feedstock of the future. Biogas from biomass delivers both methane and carbon dioxide. Anaerobic microorganisms can make additional methane from hydrogen and carbon dioxide in a biomethanation process that compares favourably with its chemical counterpart. Biomethanation for renewable power storage and use makes appropriate use of the existing infrastructure and knowledge base for natural gas. Addition of hydrogen to a dedicated biogas reactor after fermentation optimizes the biomethanation conditions and gives maximum flexibility. The low water solubility of hydrogen gas limits the methane production rate. The use of hollow fibers, nano-bubbles or better-tailored methane-forming microorganisms may overcome this bottleneck. Analyses of patent applications on biomethanation suggest a lot of freedom to operate. Assessment of biomethanation for economic feasibility and environmental value is extremely challenging and will require future data and experiences. Currently biomethanation is not yet economically feasible, but this may be different in the energy systems of the near future.
One of the issues concerning the replacement of natural gas by green gas is the seasonal pattern of the gas demand. When constant production is assumed, this may limit the injected quantity of green gas into a gas grid to the level of the minimum gas demand in summer. A procedure was proposed to increase thegas demand coverage in a geographical region, i.e., the extent to which natural gas demand is replaced by green gas. This was done by modeling flexibility into farm-scale green gas supply chains. The procedure comprises two steps. In the first step, the types and number of green gas production units are determined,based on a desired gas demand coverage. The production types comprise time-varying biogas production, non-continuous biogas production (only in winter periods with each digester having a specified production time) and constant production including seasonal gas storage. In the second step locations of production units and injection stations are calculated, using mixed integer linear programming with cost price minimization being the objective. Five scenarios were defined with increasing gas demand coverage, representing a possible future development in natural gas replacement. The results show that production locations differ for each scenario, but are connected to a selection of injection stations, at least in the considered geographical region under the assumed preconditions. The cost price is mainly determined by the type of digesters needed. Increasing gas demand coverage does not necessarily mean a much higher cost price.
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.
