Locally produced methane, - either as biomethane or power-to-gas product, has to be stored to provide a reliable gas source for the fluctuating demand of any local gas distribution network. Additionally, methane is a prominent transportation fuel but its suitability for vehicular application depends on the ability to store an adequate amount in the onboard fuel tank. Adsorption in porous materials could enable a simple, safe and cost-effective method for storing methane at ambient temperature and at reasonably low pressure. In this project we study and test the main thermodynamic and kinetic characteristics of methane adsorption and desorption on activated carbon. Both calculations and measurements are performed to enhance our knowledge about the general performance and the cyclic behavior of the adsorption and desorption processes.
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Methane storage in adsorbed form is a promising way to effectively and safely store fuel for vehicular transportation or for any other potential application. In a solid adsorbent, nanometer wide pores can trap methane by van der Waals forces as high density fluid at low pressure and room temperature. This provides the suitable technology to replace bulky and expensive cylindrical compressed natural gas tanks. Activated carbons with large surface area and high porosity are particularly suitable for methane storage applications at moderate pressures. We study and test the main thermodynamic and kinetic characteristics of methane adsorption and desorption on activated carbon.
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This report presents the experimental and numerical work carried out by ECN and Hanze University of Applied Sciences on methane sorption on activated carbon, as part of their activities within the EDGaR Energy Storage project. Eleven different activated carbon types were tested. It was found that MaxSorb MSC-30 offered the highest methane mass storage density (m/m ratio). However, due to the low density of the MaxSorb MSC-30 activated carbon, the highest volumetric methane storage density (V/V ratio) was found for Brightblack. An increase of the packing density and heat conductivity significantly improves the V/V ratio and shortens the time needed to reach thermal equilibrium. In the case of the Brightblack activated carbon, a total V/V ratio of 112 was found at 12 oC and 40 bar, implying an effective storage density that is 3 times higher than for compressed methane. During the adsorption of methane on activated carbon, sorption heat is released and the temperature of the bed is increased, which negatively affects the effective V/V ratio. Temperature rises up to 70 oC were experimentally observed at higher methane inflow rates. For MaxSorb MSC-30 a temperature rise of 25 oC reduced the effective V/V ratio by about 20 %. The temperature rise of the Brightblack bed caused relatively smaller reductions in the volumetric storage density. Calculations with the validated numerical models indicated an even higher temperature increase for the full scale methane storage, reaching bed temperatures up to 137-150 oC in the case of the MaxSorb MSC-30 activated carbon. At this temperature range, the models indicate a V/V ratio fall down to 46. This performance is similar to the one offered by direct methane compression to 40 bar, and is much lower than the V/V ratio of ~ 100 that was found both experimentally and by calculations for the lab scale reactor performance. The calculations showed, that the low bed permeability can limit the gas flow during adsorption and desorption. A high reactor diameter can countervail the effect of permeability, but the higher dimensions impede the heat dissipation and thus decrease the storage efficiency. Efficient temperature control and management are very important to effectively make use of the methane storage capacity through adsorption.
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Adsorbed natural gas (ANG) storage using metal-organic frameworks (MOFs) is a promising alter- native for efficient natural gas storage at moderate pressures. However, the presence of higher alkanes in natural gas mixtures can significantly affect storage performance by reducing methane adsorption capacity. Basolite C300, a well-studied MOF, offers high volumetric methane storage, but its long-term efficiency in real-world conditions remains a challenge due to potential pore blockage from hydrocarbon accumulation. This study investigates the long-term impact of Cn≥2 alkanes on the adsorption capacity of Basolite C300. Volumetric storage capacities of methane, individual alkanes, and a natural gas mixture were measured at 20 °C. The material underwent 100 adsorption-desorption cycles to assess the progressive impact of Cn≥2 alkanes on methane storage. The experimental results revealed a 63% reduction in methane storage capacity after 100 cycles, highlighting the detrimental effect of alkane accumulation. Higher alkanes were preferentially adsorbed within Basolite C300 micropores, leading to progressive pore blockage and decreased methane uptake. These findings underscore the critical role of gas composition in ANG systems and emphasize the need for mitigation strategies, such as selective pre-adsorption or regeneration techniques, to maintain long-term storage efficiency in MOF-based gas storage applications.
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This report focuses on the feasibility of the power-to-ammonia concept. Power-to-ammonia uses produced excess renewable electricity to electrolyze water, and then to react the obtained hydrogen with nitrogen, which is obtained through air separation, to produce ammonia. This process may be used as a “balancing load” to consume excess electricity on the grid and maintain grid stability. The product, ammonia, plays the role of a chemical storage option for excess renewable energy. This excess energy in the form of ammonia can be stored for long periods of time using mature technologies and an existing global infrastructure, and can further be used either as a fuel or a chemical commodity. Ammonia has a higher energy density than hydrogen; it is easier to store and transport than hydrogen, and it is much easier to liquefy than methane, and offers an energy chain with low carbon emissions.The objective of this study is to analyze technical, institutional and economic aspects of power-to-ammonia and the usage of ammonia as a flexible energy carrier.
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The 'AgroCycle' project investigates whether a cooperation of farms can become self-sufficient in energy and fertilization by using manure and organic waste streams for the production of energy, green fuel and green fertilizers by means of anaerobic digestion (AD). In the project, the project partners aim to link the nutrient cycle (from manure to digestate to green fertilizer) to a self-sufficient energy system (biomass to biogas to green fuel for processing the land) through the combined production of biogas and green fertilizers. The financial feasibility of a bio-digester is highly dependent on the use and economic value of the digestate. This combined approach increases both feasibility and sustainability (environmental impacts and CO2 emissions). To explore the feasibility of the aforementioned concept, use is made of the existing 'BioGas simulator' model developed by Hanze UAS to simulate the technical process of decentralized production of biogas and the economic cost.
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Arsenic contamination of groundwater is a major public health concern worldwide. The problem has been reported mainly in southern Asia and, especially, in Bangladesh. Slow-sand filters (SSF) augmented with iron were proven to be a simple, low-cost and decentralized technique for the treatment of arsenic-contaminated sources. In this research, three pilot-scale SSF (flowrate 6 L·h−1) were tested regarding their capability of removing arsenic from groundwater in conditions similar to those found in countries like Bangladesh (70 µg As(III) L−1, 26 °C). From the three, two filters were prepared with mixed media, i.e., sand mixed with corrosive iron matter (CIM filter) and iron-coated sand (ICS filter), and a third conventional SSF was used as a reference. The results obtained showed that the CIM filter could remove arsenic below the World Health Organization (WHO) guideline concentration of 10 µg·L−1, even for inlet concentrations above 150 µg·L−1. After 230 days of continuous operation the arsenic concentration in the effluent started increasing, indicating depletion or saturation of the CIM layer. The effluent arsenic concentration, however, never exceeded the Bangladeshi standard of 50 µg·L−1 throughout the whole duration of the experiments.
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In order to gain a more mature share in the future energy supply, green gas supply chains face some interesting challenges. In this thesis green gas supply chains, based on codigestion of cow manure and maize, are considered. The produced biogas is upgraded to natural gas quality and injected into the existing distribution gas grid and thus replacing natural gas. Literature research showed that relatively much attention has been paid up to now to elements of such supply chains. Research into digestion technology, agricultural aspects of (energy) crops and logistics of biomass are examples of this. This knowledge is indispensable, but how this knowledge should be combined to help understand how future green gas systems may look like, remains a white spot in the current knowledge. This thesis is an effort to fill this gap. A practical but sound way of modeling green gassupply chains was developed, taking costs and sustainability criteria into account. The way such supply chains can deal with season dependent gas demand was also investigated. This research was further expanded into a geographical model to simulate several degrees of natural gas replacement by green gas. Finally, ways to optimize green gas supply chains in terms of energy efficiency and greenhouse gas reduction were explored.
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Biogas plays an important role in many future renewable energy scenarios as a source of storable and easily extracted form of renewable energy. However, there remains uncertainty as to which sources of biomass can provide a net energy gain while being harvested in a sustainable, ecologically friendly manner. This study will focus on the utilization of common, naturally occurring grass species which are cut during landscape management and typically treated as a waste stream. This waste grass can be valorized through co-digestion with cow manure in a biogas production process. Through the construction of a biogas production model based on the methodology proposed by (Pierie, Moll, van Gemert, & Benders, 2012), a life cycle analysis (LCA) has been performed which determines the impacts and viability of using common grass in a digester to produce biogas. This model performs a material and energy flow analysis (MEFA) on the biogas production process and tracks several system indicators (or impact factors), including the process energy return on energy investment ((P)EROI), the ecological impact (measured in Eco Points), and the global warming potential (GWP, measured in terms of kg of CO2 equivalent). A case study was performed for the village of Hoogkerk in the north-east Netherlands, to determine the viability of producing a portion of the village’s energy requirements by biogas production using biomass waste streams (i.e. common grass and cow manure in a co-digestion process). This study concludes that biogas production from common grass can be an effective and sustainable source of energy, while reducing greenhouse gas emissions and negative environmental impacts when compared to alternate methods of energy production, such as biogas produced from maize and natural gas production.
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This publication gives a different take on energy and energy transition. Energy goes beyond technology. Energy systems are about people: embedded in political orders and cultural institutions, shaped by social consumers and advocacy coalitions, and interconnected with changing parameters and new local and global markets. An overview and explanation of the three end states have been extracted from the original publication and appear in the first chapter. The second chapter consists of an analysis exploring key drivers of change until 2050, giving special attention to the role of international politics, social dynamics and high-impact ideas. The third chapter explores a case study of Power to Gas to illustrate how the development of new technologies could be shaped by regulatory systems, advocacy coalitions and other functions identified in the ‘technology innovation systems’ model. The fourth chapter explores the case of Energy Valley to understand how local or regional energy systems respond to drivers of change, based on their contextual factors and systems dynamics.
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