Power-to-gas technologies are considered to be part of the future energy sys- tem, but their viability and applicability need to be assessed. Therefore, models for the viability of farm-scale bio-power-to-methane supply chains to produce green gas were analysed in terms of levelised cost of energy, energy efficiency and saving of greenhouse gas emission. In bio-power-to-methane, hydrogen from electrolysis driven by surplus renewable electricity and carbon dioxide from biogas are converted to methane by microbes in an ex situ trickle-bed reactor. Such bio-methanation could replace the current upgrading of biogas to green gas with membrane technology. Four scenarios were compared: a refer- ence scenario without bio-methanation (A), bio-methanation (B), bio-methanation combined with membrane upgrading (C) and the latter with use of renewable energy only (all-green; D). The reference scenario (A) has the lowest costs for green gas production, but the bio-methanation scenarios (B-D) have higher energy efficiencies and environmental benefits. The higher costs of the bio-methanation scenarios are largely due to electrolysis, whereas the environmental benefits are due to the use of renewable electricity. Only the all- green scenario (D) meets the 2026 EU goal of 80% reduction of greenhouse gas emissions, but it would require a CO2 price of 200 € t−1 to achieve the levelised cost of energy of 65 €ct Nm−3 of the reference scenario. Inclusion of the intermittency of renewable energy in the scenarios substantially increases the costs. Further greening of the bio-methanation supply chain and how intermittency is best taken into account need further investigation.
DOCUMENT
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.
DOCUMENT
The Bio-P2G-program (Bio-Power to Gas) at the Hanze University of AppliedSciences evaluates the technologic feasibility of the biological reduction of carbondioxide with hydrogen to methane (biomethanation: 1 CO2 + 4 H2 -> CH4 + 2 H2O)Chemically, this process is known as the Sabatier reaction, but within anaerobicdigestion the biological methanation is catalyzed by a specific group ofmicroorganisms: the hydrogenotrophic methanogens.
DOCUMENT
One potential renewable energy resource is green gas production throughanaerobic digestion (AD). However, only part of the biogas produced (up to50-60%) contains the combustible methane; the remainder are incombustiblegasses with the biggest being carbon dioxide. These gasses are often not usedand expelled in the atmosphere. Through the use of BIO-P2M where hydrogenis mixed with the remaining CO2 additional methane can be produced,increasing the yield and using the feedstocks more effectively. Within thisresearch the environmental sustainability and effectiveness of BIO-P2M isevaluated using the MEFA and aLCA method, expressed in; net green gasproduction, efficiency in (P)EROI, emissions in GWP100, and environmentalimpact in Ecopoints. The functional unit is set as a normal cubic meter ofGroningen quality natural gas. Results indicate a net improvement of allindicators when applying BIO-P2M in several configurations (in situ, ex situ).When allocating the production of renewable energy to the BIO-P2M systemenvironmental impacts for wind the results are still positive; however, whenusing solar PV as an energy source the environmental impact in Ecopointsexceeds that of the reference case of Groningen natural gas. An additionaloption for improving the indicators is optimization of the process. When usingBIO-P2M combined with heat and power unit for producing the internalelectricity and heat demands all indicators are improved substantially. On anational scale when utilizing al available waste materials for the BIO-P2Msystem around 1217 MNm3/a of green gas can be produced, which is 3% ofthe total yearly consumption in the Netherlands and around 60% more thanwhen using normal AD systems. Within the context BIO-P2M is an interestingoption for increasing green gas output and improving the overall sustainabilityof the AD process. However, the source of green electricity needs to be takeninto account and process optimization can ensure better environmentalperformance.
DOCUMENT
It is of utmost importance to collect organic waste from households as a separate waste stream. If collected separately, it could be used optimally to produce compost and biogas, it would not pollute fractions of materials that can be recovered from residual waste streams and it would not deteriorate the quality of some materials in residual waste (e.g. paper). In rural areas with separate organic waste collection systems, large quantities of organic waste are recovered. However, in the larger cities, only a small fraction of organic waste is recovered. In general, citizens dot not have space to store organic waste without nuisances of smell and/or flies. As this has been the cause of low organic waste collection rates, collection schemes have been cut, which created a further negative impact. Hence, additional efforts are required. There are some options to improve the organic waste recovery within the current system. Collection schemes might be improved, waste containers might be adapted to better suit the needs, and additional underground organic waste containers might be installed in residential neighbourhoods. There are persistent stories that separate organic waste collection makes no sense as the collectors just mix all municipal solid waste after collection, and incinerate it. Such stories might be fuelled by the practice that batches of contaminated organic waste are indeed incinerated. Trust in the system is important. Food waste is often regarded as unrein. Users might hate to store food waste in their kitchen that could attract insects, or the household pets. Hence, there is a challenge for socio-psychological research. This might also be supported by technology, e.g. organic waste storage devices and measures to improve waste separation in apartment buildings, such as separate chutes for waste fractions. Several cities have experimented with systems that collect organic wastes by the sewage system. By using a grinder, kitchen waste can be flushed into the sewage system, which in general produces biogas by the fermentation of sewage sludge. This is only a good option if the sewage is separated from the city drainage system, otherwise it might create water pollution. Another option might be to use grinders, that store the organic waste in a tank. This tank could be emptied regularly by a collection truck. Clearly, the preferred option depends on local conditions and culture. Besides, the density of the area, the type of sewage system and its biogas production, and the facilities that are already in place for organic waste collection are important parameters. In the paper, we will discuss the costs and benefits of future organic waste options and by discussing The Hague as an example.
DOCUMENT
Innovations are required in urban infrastructures due to the pressing needs for mitigating climate change and prevent resource depletion. In order to address the slow pace of innovation in urban systems, this paper analyses factors involved in attempts to introduce novel sanitary systems. Today new requirements are important: sanitary systems should have an optimal energy/climate performance, with recovery of resources, and with fewer emissions. Anaerobic digestion has been suggested as an alternative to current aerobic waste water treatment processes. This paper presents an overview of attempts to introduce novel anaerobic sanitation systems for domestic sanitation. The paper identifies main factors that contributed to a premature termination of such attempts. Especially smaller scale anaerobic sanitation systems will probably not be able to compete economically with traditional sewage treatment. However, anaerobic treatment has various advantages for mitigating climate change, removing persistent chemicals, and for the transition to a circular economy. The paper concludes that loss avoidance, both in the sewage system and in the waste water treatment plants, should play a key role in determining experiments that could lead to a transition in sanitation. http://dx.doi.org/10.13044/j.sdewes.d6.0214 LinkedIn: https://www.linkedin.com/in/karel-mulder-163aa96/
MULTIFILE
Global society is confronted with various challenges: climate change should be mitigated, and society should adapt to the impacts of climate change, resources will become scarcer and hence resources should be used more efficiently and recovered after use, the growing world population and its growing wealth create unprecedented emissions of pollutants, threatening public health, wildlife and biodiversity. This paper provides an overview of the challenges and risks for sewage systems, next to some opportunities and chances that these developments pose. Some of the challenges are emerging from climate change and resource scarcity, others come from the challenges emerging from stricter regulation of emissions. It also presents risks and threats from within the system, next to external influences which may affect the surroundings of the sewage systems. It finally reflects on barriers to respond to these challenges. http://dx.doi.org/10.13044/j.sdewes.d6.0231 LinkedIn: https://www.linkedin.com/in/sabineeijlander/ https://www.linkedin.com/in/karel-mulder-163aa96/
MULTIFILE
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.
DOCUMENT
During the opening of the Hanze Energy Transition Centre or EnTranCe (2015-10-13) posters were on display for the King and for the public. During the opening these posters where accompanied by the researchers to explain their research in more detail if questions did arise.
DOCUMENT
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.
LINK
