The dairy sector in the Netherlands aims for a 30% increase in efficiency and 30% carbon dioxide emission reduction compared to the reference year of 1990, and a 20% share of renewable energy, all by the year 2020. Anaerobic Digestion (AD) can play a substantial role in achieving these aims. However, results from this study indicate that the AD system is not fully optimized in combination with farming practices regarding sustainability. Therefore, the Industrial Symbiosis concept, combined with energy and environmental system analysis, Life Cycle Analysis and modeling is used to optimize a farm-scale AD system on four indicators of sustainability (i.e., energy efficiency, carbon footprint, environmental impacts and costs). Implemented in a theoretical case, where a cooperation of farms share biomass feedstocks, a symbiotic AD system can significantly lower external energy consumption by 72 to 92%, carbon footprint by 71 to 91%, environmental impacts by 68 to 89%, and yearly expenditures by 56 to 66% compared to a reference cooperation. The largest reductions and economic gains can be achieved when a surplus of manure is available for upgrading into organic fertilizer to replace fossil fertilizers. Applying the aforementioned symbiotic concept to the Dutch farming sector can help to achieve the stated goals indicated by the Dutch agricultural sector for the year 2020.
Source Segregation (SS) is a novel strategy in dairy housing that can reduce emissions and separate organic matter and nutrients more efficiently than traditional slurry solid-liquid separation. The anaerobic digestion (AD) methane yield of the SS fractions, however, is unknown. We aimed at unveiling the biomethane yield of these fractions by conducting AD experiments under different configurations: batch, continuous feeding, and fed-batch. In the batch test, the solid (SF) and liquid fraction (LF) from the SS system, a slurry collected from the pit (CS), and a self-made slurry (MF) were used as substrates. The results showed that the specific CH4 yields of the SF and MF were in same range and both higher than the CS. We concluded that SS can increase the CH4 yield of dairy excreta mainly by reducing losses in the animal house. The SF and MF were then compared in a continuously-fed thermophilic test, where SF had a higher specific (174 compared to 105 NL kg-1 VS) and volumetric (12.2 compared to 9.9 NL CH4 kg-1 excreta) yields. We concluded that the SF can effectively substitute slurry in AD without compromising the yield, possibly increasing economic viability by reducing transport costs and reactor size. Further, SF produced 356 NL CH4 kg-1 VS and a digestate with 1.8% lower dry matter in the fed-batch as compared to continuous feeding. Continuously stirred fed-batch can thus increase the CH4 yield of the SF and reduce the DM of its digestate potentially contributing to lower emissions in storage and field application.
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Anaerobic digestion (AD) can play an important role in achieving the renewable energy goals set within the European Union. Within this article the focus is placed on reaching the Dutch local renewable production goal set for the year 2020 with locally available biomass waste flows, avoiding intensive farming and long transport distances of biomass and energy carriers. The bio-energy yields, efficiency and environmental sustainability are analyzed for five municipalities in the northern part of the Netherlands, using three utilization pathways: green gas production, combined heat and power, and waste management. Literature has indicated that there is sufficient bio-energy potential in local waste streams to reach the aforementioned goal. However, the average useful energy finally produced by the AD production pathway is significantly lower, often due to poor quality biomass and difficult harvesting conditions. Furthermore, of the potential bio-energy input in the three utilization pathways considered in this article, on average: 73% can be extracted as green gas; 57% as heat and power; and 44% as green gas in the waste management pathway. This demonstrates that the Dutch renewable production goal cannot be reached. The green gas utilization pathway is preferable for reaching production goals as it retains the highest amount of energy from the feedstock. However, environmental sustainability favors the waste management pathway as it has a higher overall efficiency, and lower emissions and environmental impacts. The main lessons drawn from the aforementioned are twofold: there is a substantial gap between bio-energy potential and net energy gain; there is also a gap between top–down regulation and actual emission reduction and sustainability. Therefore, a full life cycle-based understanding of the absolute energy and environmental impact of biogas production and utilization pathways is required to help governments to develop optimal policies serving a broad set of sustainable objectives. Well-founded ideas and decisions are needed on how best to utilize the limited biomass availability most effectively and sustainably in the near and far future, as biogas can play a supportive role for integrating other renewable sources into local decentralized energy systems as a flexible and storable energy source.
In the last decade, the concept on interactions between humans, animals and their environment has drastically changed, endorsed by the One Health approach that recognizes that health of humans and animals are inextricably linked. Consideration of welfare of livestock has increased accordingly and with it, attention into the possibilities to improve livestock health via natural, more balanced nutrition is expanding. Central to effects of healthy nutrition is an optimal gastrointestinal condition which entails a well-balanced functional local immune system leading to a resilient state of well-being. This project proposal, GITools, aims to establish a toolbox of in vitro assays to screen new feed ingredients for beneficial effects on gastrointestinal health and animal well-being. GITools will focus on pig and chicken as important livestock species present in high quantities and living in close proximity to humans. GITools builds on intestinal models (intestinal cell lines and stem cell-derived organoids), biomarker analysis, and in vitro enzymatic and microbial digestion models of feed constituents. The concept of GITools originated from various individual contacts and projects with industry partners that produce animal feed (additives) or veterinary medicines. Within these companies, an urgent need exists for straightforward, well-characterized and standardized in vitro methods that provide results translatable to the in vivo situation. This to replace testing of new feed concepts in live animal. We will examine in vitro methods for their applicability with feed ingredients selected based on the availability of data from (previous) in vivo studies. These model compounds will include long and short chain fatty acids, oligosaccharides and herbal-derived components. GITools will deliver insights on the role of intestinal processes (e.g. dietary hormone production, growth of epithelial cells, barrier function and innate immune responses) in health and well-being of livestock animals and improve the efficiency of testing new feed products.
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.
