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Majority of Dutch peatlands are drained and used intensively as grasslands for dairy farming. This delivers high productivity but causes severe damage to ecosystem services supply. Peatland rewetting is the best way to reverse the damage, but high water levels do not fit with intensive dairy production. Paludiculture, defined as crop production under wet conditions, provides viable land use alternatives. However, performance of paludiculture is rarely compared to drainage-based agriculture. Here, we compared the performances of six land use options on peatland following a gradient of low, medium, and high water levels, including conventional and organic drainage-based dairy farming, low-input grasslands for grazing and mowing, and high-input paludiculture with reed and Sphagnum cultivation. For each land use option, we conducted environmental system analysis on model farm system defined by a literature based inventory analysis. The analysis used five ecosystem services as indicators of environmental impacts with a functional unit of 1-ha peat soil. Ecosystem services included biomass provisioning, climate, water, and nutrient regulation, and maintenance of habitat. Results showed that drainage-based dairy farming systems support high provisioning services but low regulation and maintenance services. Organic farming provides higher climate and nutrient regulation services than its conventional counterpart, but limited overall improvement due to the persistent drainage. Low-intensity grassland and paludiculture systems have high regulation and maintenance services value, but do not supply biomass provisioning comparable to the drainage-based systems. Without capitalizing the co-benefits of regulation and maintenance services, and accounting for the societal costs from ecosystem disservices including greenhouse gas emission and nitrogen pollution, it is not likely that the farmers will be incentivized to change the current farming system towards the wetter alternatives. Sustainable use of peatlands urges fundamental changes in land and water management along with the financial and policy support required.

Dairy farms require a significant amount of nitrogen to enter the production system via cattle fodder, which in intensive farming can be traced back to artificial fertilizers. As a by-product of dairy farms, cattle manure contains undigested nitrogen that allows the farmers to reuse it for their grassland and reduce net imported artificial nitrogen. The manure is traditionally applied directly on the land, however nowadays, when anaerobic digestion is adopted, the farmers can gain extra income from biogas production and still have nitrogen remaining in the digestate to use as a fertilizer. To increase the biogas yield, the farmers can also decide to digest their manure with other co-feeds. As a consequence of using co-feeds for biogas digesters, the nitrogen concentration in the digestate is largely increased and this allows the recycled nitrogen flow to exceed the boundary of the dairy. Nevertheless, it is noticed that the recycled nitrogen flow is never a closed loop because of the continuous stream of nitrogen that leaves the system via the dairy products. Therefore it is interesting to figure out to which extent different options of biogas production and nutrient recycling can help farmers to reduce their dependency on artificial nitrogen. This study is a material flow analysis of nitrogen around intensive dairy farms combined with biogas production. Based on a literature review, we map different recycling fates of nitrogen in this combined system and then use material flow accounting to assess how different system configurations impact the potential for nitrogen cycling. Nitrogen recovery can be achieved via four potential recycling loops: 1) direct application of manure to the grassland of the dairy farm 2) mono-digestion; the digestate is applied directly to grassland of the dairy farm; 3) co-digestion; the digestate is applied directly on both the dairy farm and the farm which provides co-feed for the production; 4) co-digestion; nitrogen in the digestate is extracted to produce artificial fertilizers and then comes back to the dairy farm and to the farm which provides co-feed for the production. These models were examined with different co-feeds which vary on nitrogen content and biogas yield. The results provide an overview of the different extents of the circularity of recycling nitrogen in the combined system of biogas production and related agriculture production. In a broader perspective, the results also point out that the quantitative characteristics of a material flow play a critical role in the feasibility of its recycling pathways.

Biomass can play a role in the transition to a sustainable energy system. In principle all biomass can be used for make biogas. However, biogas yields differ for the various biomass types. Next to this, biomass is also used for other needs like food and feed. These competing uses affect the price of the biomass on the market. For getting insight into the potential of biogas as a future energy source it is essential to have an overview of competing uses of available biomass sources. Knowledge of the competing uses of each type of biomass is scattered throughout literature. Reviewing literature manually for this information is immensely time-consuming and limited by human reading capacity. For that reason, in this study we applied a machine learning technique to perform a large literature review to provide an extensive review of current competing valorization pathways of biogas feedstocks. To do this, we first gathered literature abstracts related to biogas feedstock valorization pathways from academic databases. The abstracts were then automatically scanned for mentions of terms contained in a list of feedstocks and a list of valorizations. The list of biogas feedstocks was taken from the European Feedstock Atlas. The list of biomass valorizations was created based on the Biomass Value Pyramid which mainly categorizes the use of biomass into four groups: Food for humans, Feed for animals, Biobased materials and Energy. To further evaluate which feedstocks were mentioned with which valorization pathways, we used a machine learning technique called cooccurrence analysis, which analyzes the significance of two terms appearing together in the same abstract, compared to how likely they would appear together just based on chance. This assisted with the process of identifying actual valorization pathways versus false positives. For further validation, for each cooccurrence of feedstocks and valorization options, we were able to trace back the abstracts mentioning that combination. The final result is a webbased visualization of a map which shows the connection of biogas feedstocks together with their all competing uses. Feedstock valorizations are colormarked in an increasing magnitude order corresponding to the increasing value of biomass. The visualization also shows the heaviness of the connection between each biomass and its different uses based on the significance of cooccurrence of them in literatures, which can be related to the commonness of the biomass use in practice. Beyond the goal of visualizing the connections between biogas substrates and their competing uses, the map provides ideas to explain phenomena in the biomass market such as prices and preferences. Lastly, this map is a reminder for biogas concerned parties to make the production plan based on practical availability rather than only technical information of the feedstocks.

Dairy manure-based biogas, an emerging source of renewable energy, is a result of a recycling process which often leads to the thought that manure production is the beginning of this biogas supply chain by energy producers. However, dairy manure is only a byproduct of an agricultural system whose main activities are crops and milk production. And thus, researching a combined biogas and agricultural production system provides a more comprehensive and systematic view of opportunities and impacts resulting from biogas production. Nitrogen is a critical input for any agricultural production system. Crops need nitrogen for their growth. Dairy farmers make decisions on nitrogen inputs for their cows by choosing co-feeds which result in different levels of milk production. The undigested nitrogen is often recycled by returning manure or biogas digestate to the fields. Choices related to milk production influence the amount of manure and nitrogen concentration of the farm (Nennich et al., 2005) which eventually affects the production of biogas as well as its nitrogen-related environmental problems. On the other hand, alternatives strategies for biogas production which may result in higher biogas yields, such as the use of certain co-substrates and mixing ratios, might also make the nitrogen contained in the digestate heavily exceed the need of the dairy farm. For these reasons, this paper researches the mutual interaction between biogas production and its agricultural production via the nitrogen flows within the combined system. In order to do that, the research first quantitatively modelled the nitrogen flows within the combined system which actually happen in practice. The combined system boundary includes the dairy farm itself where the choice of milk and biogas production are made; the co-feed farm and the co-substrate farm (Figure 1). We used the indicator of nitrogen recycling potential which is the ratio between the amount of nitrogen required by the agriculture system and the nitrogen contained in the manure or digestate produced by the dairy farm. We also varied animal density of the farm, options for milk and biogas production as well as crop characteristics such as biogas yield and harvest yield to investigate the influence of these factors on the nitrogen recycling potential of the system. At the end, we implemented an optimization on top of the material accounting model to figure out which commonly used crops would bring the best nitrogen recycling potential in certain combinations of biogas and milk production. The model observed that the nitrogen recycling advantage of one production combination in comparison with others might switch based on levels of a farm’s animal density; and these switching points are unforeseen by simple calculations. Therefore, to make wise decisions of nitrogen use and recycling for dairy manure-based biogas system, a quantitative material flow model is beneficial. Furthermore, we examined the nitrogen recycling potential from a perspective of the dairy farm itself and of the whole agriculture production system. The results showed that high biogas production or high milk production does not always couple with high nitrogen recycling potential, which leaves us a discussion on the trade-offs among these production options.

Energy is the vital input for sustainable development of a country as it is directly related to the country’s economic growth. Even though energy use has doubled since 2000, but energy consumption per capita is still only around one-third of the global average and some 240 million people have no access to electricity. This study investigates the present energy demand scenario of a rural village and finds the possibilities of achieving energy access by the available alternate energy in rural areas. A detailed survey was done on the energy demand and available energy resources in a village of Assam in the Northeastern part of India. Energy demands on different sectors were calculated and the sources of energy were studied. The total technical bioenergy potential is 3.0 MWh per year from available rice husk only. The result implies that there are abundant of untapped bioenergy resources available in the village and alternatives to diversify its source of energy. This research concludes that the energy demand of households varies intensely with national averages. This bottom-up approach study of a rural village is to understand the domestic scenario of villages in developing countries, as it can be related to other villages to a much extent.