Exploitation of Mowed Grass from Green Areas by Means of Anaerobic Digestion: Effects of Grass Conservation Methods (Drying and Ensiling) on Biogas and Biomethane Yield.

Abstract: Grass from landscape management or from agricultural practices is currently destined mainly for composting, with the production of a valuable product; however, this process demands energy. Anaerobic digestion, instead, represents an energy-positive process that results in the production of fuel, biogas, and a fertilizer, namely digestate. Previous tests for the evaluation of biogas yield from freshly harvested grass gave promising results. However, for a practical exploitation of this resource, appropriate conservation is necessary in order to enable the daily load of digesters while reducing the loss of organic matter. The present work is focused on the evaluation of biogas and methane yield from dried and ensiled grass (without conditioning) in order to assess eventual biogas potential losses in comparison to digested fresh grass. Tests were performed with grass collected from riverbanks (Veneto, Northern Italy) in batch, lab scale digesters. Dry and ensiled grass showed a good potential for exploitation in the anaerobic digestion process, reaching biogas yields of 565.9 and 573.4 NL 19kgVS 121, respectively. Compared to the biogas yield of 639.7 NL 19kgVS 121 of the fresh grass, the conservation treatment determined yield reductions of 11.5% and 10.4% for dried and ensiled grass, respectively. However, considering the methane yields, conservation treatments showed lower reductions, amounting to 4.8% for dry grass and 0.5% for ensiled grass; presumably the higher concentration of organic acids in ensiled grass determined a higher methane content in biogas and the consequently lower reduction of methane yield

Tractor cabin ergonomics analyses by means of Kinect motion capture technology

Kinect is the de facto standard for real-time depth sensing and motion capture cameras. The sensor is here proposed for exploiting body tracking during driving operations. The motion capture system was developed taking advantage of the Microsoft software development kit (SDK), and implemented for real-time monitoring of body movements of a beginner and an expert tractor drivers, on different tracks (straight and with curves) and with different driving conditions (manual and assisted steering). Tests show how analyses can be done not only in terms of absolute movements, but also in terms of relative shifts, allowing for quantification of angular displacements or rotations

Energy evaluation of grass residues supply chain from non-cultivated areas for biogas feeding

The increasing demand of biomass for biogas production is arousing some concerns about the sustainability of this process. In fact, the cultivation of energy crops in farmlands is becoming more noticeable, causing a competition with food production. The utilisation of grass from the management of territory as a feedstock for the anaerobic digestion process could contribute to reduce these problems, both on environmental and social aspects. In fact, grass exploitation, beyond minimize the competition with food, could reduce eutrophication and production of greenhouse gases, provide nutrients for the fertilization of the soils and make more profitable the management of landscape and the biogas production

Energy valorisation of grass residues collected from non-cultivated areas

Large amounts of grass residues derived from uncultivated areas are present in European regions. This biomass, which generally does not compete with food production and is partially recovered for animal feeding, represent an interesting feedstock for the supply of anaerobic digestion plants to produce renewable energy. This thesis focused on the valorisation of grass from uncultivated areas in the anaerobic digestion supply chain, with particular attention on the Veneto region. To achieve this objective, several research works have been performed in order to: -Assess the potential areas and the biomass availability considering the situation of the Veneto region; -Define the best technologies for grass mowing, harvesting, logistic and utilization in the economic, energy and environmental aspects; -Determinate the energy and environmental balance that can derive from grass valorisation in the biogas supply chain. In a first study, we demonstrated through a GIS based approach that large availability of residual grass is present in the Veneto Region, which it could be potentially utilized for anaerobic digestion. Grass from landscape management, such riverbanks, natural areas or parks, is of more interest for the energy generation in agricultural anaerobic digestion plants. The harvesting of grass in these areas can be performed with different solutions. The total costs generally are high, however systems with better operative performances can reduce the economic and energy costs due to the specialized mechanization required. Conceiving grass logistic, direct transport chain seems to be the most convenient solution under economical and energy aspects for the management of such material in short distances due to less mechanisations inputs requirement. Conversely, in longer distances, the best solution appears to be the interrupted transport chain due to the higher transport capacities. The biochemical methane potential of grass is interesting, showing that a good amount of energy can be recovered. Closing the whole energy and greenhouse gases balances is shown that the recovery of grass for energy purposes is sustainable. As consequence, grass recovering represent and opportunity to reduce the dependency of anaerobic digestion sector on energy crops and obtain a positive return, in terms of energy and emissions saved, from the landscape management operations, creating interesting job opportunities.L’erba proveniente da aree non coltivate rappresenta un’interessante biomassa per l’alimentazione di impianti a digestione anaerobica. Tale biomassa generalmente non compete con la produzione alimentare e raramente viene recuperata per fini alimentari. L’obbiettivo di questa tesi riguarda la valorizzazione di erba da aree non coltivate per l’alimentazione di impianti a biogas, con particolare attenzione alla regione Veneto. Il raggiungimento di tale obiettivo è stato possibile attraverso diversi lavori di ricerca, con l’obbiettivo di: -Valutare il potenziale quantitativo di biomassa nella regione Veneto; -Definire le migliori tecnologie per il taglio, la raccolta, la logistica e l'utilizzazione dell’erba considerandone gli aspetti economici, energetici e ambientali; -Determinare il bilancio energetico e ambientale derivante dalla valorizzazione nella filiera di produzione del biogas. In un primo studio abbiamo dimostrato attraverso un approccio basato su GIS che in Veneto è presente una grande disponibilità di residui d’erba potenzialmente utilizzabili nella digestione anaerobica. In questo senso, l'erba derivante della gestione del paesaggio, come le banchine fluviali, le aree naturali, o i parchi, risulta essere di maggiore interesse per la produzione di energia negli impianti agricoli a digestione anaerobica. La raccolta di erba in queste aree può essere eseguita con diverse soluzioni. I costi complessivi sono generalmente elevati, tuttavia i sistemi con migliori capacità operative possono ridurre i costi economici e energetici. Considerando la logistica dell’erba, l’approccio a trasporto diretto risulta essere la soluzione più conveniente sotto gli aspetti economici e energetici per brevi distanze a causa di minori input di meccanizzazione. Viceversa, in lunghe distanze, la soluzione migliore risulta essere l’approccio di trasporto interrotto a causa delle maggiori capacità di trasporto. Dagli studi si è potuto constatare inoltre che il potenziale metanigeno dell'erba è interessante, evidenziando una buona quantità di energia potenzialmente recuperabile. I bilanci energetici e dei gas serra dimostrano che il recupero dell'erba per scopi energetici è sostenibile. Di conseguenza, il recupero dell'erba a fini energetici potrebbe costituire un'opportunità per il settore della produzione di biogas di ridurre la dipendenza da colture energetiche e ottenere un ritorno positivo, in termini di energia e di emissioni, dalla gestione del paesaggio, con la possibilità di creare interessanti opportunità di lavoro

Energy valorisation of grass residues collected from non-cultivated areas

Large amounts of grass residues derived from uncultivated areas are present in European regions. This biomass, which generally does not compete with food production and is partially recovered for animal feeding, represent an interesting feedstock for the supply of anaerobic digestion plants to produce renewable energy. This thesis focused on the valorisation of grass from uncultivated areas in the anaerobic digestion supply chain, with particular attention on the Veneto region. To achieve this objective, several research works have been performed in order to: -Assess the potential areas and the biomass availability considering the situation of the Veneto region; -Define the best technologies for grass mowing, harvesting, logistic and utilization in the economic, energy and environmental aspects; -Determinate the energy and environmental balance that can derive from grass valorisation in the biogas supply chain. In a first study, we demonstrated through a GIS based approach that large availability of residual grass is present in the Veneto Region, which it could be potentially utilized for anaerobic digestion. Grass from landscape management, such riverbanks, natural areas or parks, is of more interest for the energy generation in agricultural anaerobic digestion plants. The harvesting of grass in these areas can be performed with different solutions. The total costs generally are high, however systems with better operative performances can reduce the economic and energy costs due to the specialized mechanization required. Conceiving grass logistic, direct transport chain seems to be the most convenient solution under economical and energy aspects for the management of such material in short distances due to less mechanisations inputs requirement. Conversely, in longer distances, the best solution appears to be the interrupted transport chain due to the higher transport capacities. The biochemical methane potential of grass is interesting, showing that a good amount of energy can be recovered. Closing the whole energy and greenhouse gases balances is shown that the recovery of grass for energy purposes is sustainable. As consequence, grass recovering represent and opportunity to reduce the dependency of anaerobic digestion sector on energy crops and obtain a positive return, in terms of energy and emissions saved, from the landscape management operations, creating interesting job opportunities

Role of bilateral adrenalectomy in Cushing's disease

Abstract: Of 206 patients with Cushing's syndrome observed from 1975 through 1991, 144 (69.9%) had pituitary-dependent Cushing's disease. Of the 110 patients who underwent pituitary surgery, 31 (28%) developed an early recurrence and 23 patients (20%) had a late relapse 1 to 5 years after primary pituitary exploration. We performed a one- or two-step total bilateral adrenalectomy in 43 patients-9 men and 34 (79.4%) women, with an average age of 47.5 years (range 13-58 years). Thirty-three of these patients had already been treated by previous transsphenoidal surgery or alternatively by external pituitary irradiation over a period of 1 to 10 years prior to adrenal surgery. Thirty one patients underwent adrenalectomy by a double lumbar access or left lumbar and right subcostal incisions. In our series of 55 operations, perioperative complications included two splenectomies and two hemorrhages (7.3%). The early mortality rate was 3.6% (two patients). Minor complications consisted of wound infection (13.5%), bronchopneumonia or pneumothorax (four cases) with a 7- to 12-day longer hospital stay. Nelson syndrome occurred in 6 of 41 patients (14.6%). We therefore believe that bilateral adrenalectomy does play a major role in the treatment of patients with pituitary-dependent Cushing's disease unsuccessfully managed by transsphenoidal surgery. It represents the definitive therapy for those patients in whom hypophysectomy was not able to provide satisfactory control of the disease

Alternative maize ensiling techniques for anaerobic digestion process: Economic and energetic comparison

Currently, biomasses contribute to the European energy supply-chain by an average amount of 4%. With reference to the Italian situation, in the last years about 10% of the overall maize area is earmarked to biogas production causing a changing in its harvesting operations. In particular, due to the wide surface to collect in a short harvesting period, the mowing, chopping, transport and ensiling operations must be well adapted in order to avoid bottlenecks that otherwise would lead to unproductive periods of delay, idle machines and, as a result, higher costs that could reduce the overall efficiency. Ensiling, in this sense, is one of the key issues that could affect the sustainability of such biomass, both from an economical and environmental point of view. In fact, several ensiling techniques can be carried out. However, among them, in Europe, the two most widespread are: bunker silos (traditional systems) and plastic bag-silos. While the bunker silos represent so far the most utilized solution, the plastic bag silos could be a potentially cheaper alternative to traditional silage storage systems. The aim of this study is to compare the economical and energy aspects of the two most important ensiling techniques for maize silage production aiming to detect the solution having lower costs and impact on the environment

Energy parameters and feedstock management in farm-scale biogas plants: Survey in the North-East of Italy

Biogas production from agricultural energy crops is considered as a promising alternative to reduce the current dependence on non-renewable energy sources. Among these, Anaerobic Digestion (AD) of different feedstock has proved to be an interesting energy source in rural areas, especially when the AD plants are fed with local available feedstock and the energy generated is used near the plant. Nowadays, more than 1100 agricultural biogas plants are operating in Italy, particularly in the northern regions. In Italy biogas plants are mainly concentrated in Po Valley regions, (Lombardia, Piemonte, Emilia-Romagna and Veneto); although the biogas policy scheme concerns all the country, these regions have a highly productive agricultural system and densely populated urban areas. In this paper, real operative data (gas yield and feedstock management) of 28 farm-scale biogas plants localized in the Po Valley (North-Eastern Italy) are summarized and analyzed to investigate the increasing factors of biogas production and identify the important parameters for further positive developments. The survey results suggest a positive outlook for other crops and agricultural waste integration into the AD supply chain. More than half of the biogas plants present a nominal power higher than 2.2 MW and electric power values that in 60.7 % of the cases amount to 0.999 MWe, in order to remain into the dimensional limits and to benefit from the maximum energetic incentive