Anaerobic digestion (AD) can play an important role in achieving renewable goals set within the Netherlands which strives for 40 PJ bio-energy in the year 2020. This research focusses on reaching this goal with locally available biomass waste flows (e.g. manures, grasses, harvest remains, municipal organic wastes). Therefore, the bio-energy yields, process efficiency and environmental sustainability are analyzed for five municipalities in the northern part Netherlands, using three utilization pathways: green gas production; combined heat and power; and waste management. Results indicate that the Dutch goal cannot be filled through the use of local biomass waste streams, which can only reach an average of 20 PJ. Furthermore renewable goals and environmental sustainability do not always align. Therefore, understanding of the absolute energy and environmental impact of biogas production pathways is required to help governments form proper policies, to promote an environmentally and social sustainable energy system.
Far from being negligible in quantity, decentralized energy production delivers a considerable part of the renewable energy production in the Netherlands. Decentralized production takes place by individual households, companies as well as citizen groups. Grassroots initiatives have sprung up in the Netherlands in the last 5 years, in a recent inventory 313 formally instituted local energy cooperatives were found. Cooperatives’ aims are sustainability, strengthening local economy and promoting a democratic governance structure for energy production.The energy industry in the Netherlands has traditionally been dominated by large energy companies, and the Groningen gas field has resulted in a very high dependency on natural gas for both consumer and business households. The climate for grassroots initiatives has improved since the so-called Energy Covenant in 2013. This covenant pertains to an agreement between government, industry representatives, labor unions and non-governmental organizations to arrive at a substantial reduction of energy use, ambitious increase in the production of renewable energy, and new jobs in the renewable energy sector.The covenant also announced new policies to stimulate community energy activities, such as the Zip-code-rose policy . The governmental interest in new forms of energy transition, is also demonstrated by the ‘Experiments Electricity Law’ facility, which gives local business and community initiatives an opportunity to experiment with a local energy system. This policy is meant as a ‘learning facility’; experiences are expected to lead to adaptations in Dutch electricity law and regulation.
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.
