Browsing by Subject "biogas"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Zhao, Chuanhui (Helsingin yliopisto, 2020)
    The research of this thesis was focused on anaerobic digestion of cow manure mixed with different types of biowaste, especially those material that are available in Finland. The research was conducted by search, collection, and analysis of different data in literature. Topic of the thesis was predetermined by the Co-Creation Lab project of Helsinki Institute of Sustainability Science (HELSUS), which was seeking solution to achieve carbon neutral cow milk production. The solution was co-approached by three participants conducting thesis from technological, economical, and legislative points of view, in which I was responsible for writing mainly the technological part, and general findings in economic efficiency and legislative terms by the other two co-creators were also included in this thesis. The research was mainly related with the whole cycle of biogas production, including basics about anaerobic digestion (AD), applications of the biogas and digestate as a product and by-product of AD. Substrates for AD were researched with a focus to find the best combination of cow manure (CM) and biowaste in regard with methane yield outcome, especially a mixture of CM and silage waste that suits the cow farming situation in Finland. Methane yields for mono-digestion of various types of biowaste and co-digestion of CM with different biomass were collected and analyzed. Premises for biogas plant establishment were researched briefly, including facility composition, and consideration of feasibility and raw material availability. CM with grass containing 75% timothy and 25% meadow fescue grass at 70%:30% mixing ratio could be the best combination of CM: grass co-digestion, followed by 0.5:0.5 mixed CM and perennial ryegrass. Furthermore, CM mixed with food waste at 52:48% ratio could be the best combination among co-digestion of CM with biowaste other than grass, followed by CM and food waste mixed with 68%:32% ratio, and CM with oat straw mixed at 1:2 ratio could be a considerable combination of CM and crop waste.
  • Lyytimäki, Jari (Elsevier, 2018)
    Sustainable Production and Consumption 15 (2018), pages 65-73
    Decentralised production and consumption of biogas is often argued to provide multiple opportunities for accelerating the transition towards sustainable development. This research focuses on the long-term coverage of biogas in two widely read Finnish newspapers. The results show a relatively voluminous professional but weaker and scattered mainstream media coverage of biogas. Four key storylines of public debate relevant for sustainability transition are investigated. First, the environmental impacts of biogas have been described under strikingly positive framings highlighting a potential for various environmental benefits. In particular, growing emphasis has been placed on natural resource management following the idea of circular economy. Second, the economic storyline has casted doubts on profitability of biogas production by emphasising the need for public subsidies. Newspaper coverage has focused on the micro level economic performance of energy producers and left the macro level economic implications of biogas with little attention. Third, the energy policy storyline has framed biogas predominantly as a local-level solution without extensively discussing a national level target setting for biogas. Fourth, the technology storyline has been relatively thin and it has emphasised the novelty of biogas production without highlighting any major technological problems or risks. Overall, the newspaper coverage of biogas has not seriously challenged the dominant energy discourse taking the centralised energy production as a self-evident overall context of national energy system. The results suggest that there exists a considerable variation between different media and between different national contexts. These variations should be taken into account when designing and implementing energy policies.
  • Hagel, Sebastian; Kirjoranta, Satu; Mikkonen, Kirsi S.; Tenkanen, Maija; Körner, Ina; Saake, Bodo (2021)
    Street tree pruning residues are a widely available and currently undervalorized bioresource. Their utilization could help alleviate an increasing biomass shortage and offset costs of the pruning process for the municipalities. In this work, a holistic valorization pathway of pruning residues leading to fibers, oligosaccharides, biogas, and compost is presented. For this, representative mixtures of tree pruning materials from the most prevalent street tree genera (oak, linden, maple) found in Hamburg (Germany) were prepared by shredding and cleaning procedures. Collection of sample material was performed in summer and winter to account for seasonality. A steam-based fractionation was conducted using treatment severities ranging from log R-0 = 2.5 to 4.0. At the highest severity, a fiber yield of around 66%, and liquor yield of 26-30% was determined. The fibers were evaluated with respect to their properties for paper product applications, with higher treatment severities leading to higher paper strengths. From the oligosaccharide-rich liquor, emulsions were created, which showed promising stability properties over 8 weeks of storage. The liquors and the rejects from the material preparation also displayed good potential for biomethane production. Overall, the differences between material collected in summer and winter were found to be small, indicating the possibility for a year-round utilization of pruning residues. For the presented utilization pathway, high severity treatments were the most promising, featuring a high liquor yield, good biomethane potential, and the highest paper strengths.
  • Valve, Helena; Lazarevic, David; Humalisto, Niko (Elsevier, 2021)
    Ecological Economics 185 (2021), 107025
    The circular economy operates as an umbrella concept for attempts to find sustainable alternatives to linear ‘take-make-dispose’ production and consumption systems. Making a circular economy transformation has sparked interest in business models as means to decouple value creation and the use of virgin raw materials. However, so far, little attention has been given to the differentiating capacities of business models to enhance circularity. Using Finnish biogas production as a case study, this paper shows how business models operating within a single economic domain and within uniform institutional conditions differ in terms of how they organise material circuits. Four business models are differentiated based on what wastes and side-flows they enable to be recovered, and how. Because the business models co-evolve, their potentials are analysed in relation to the business model ecosystem. An emerging business model competes with the dominating model. The newcomer would help to generate more closed material loops, but the existing institutional landscape fails to provide support for its emerging modes of value creation and value capture. Two other business models qualify as niche solutions coexisting with the other models. Knowing the business model ecosystem opens up prospects for policy revisions that can foster a more circular economy.