85 research outputs found
Life cycle environmental analysis of a hydrogen-based energy storage system for remote applications
No full textEnergy storage systems are required to address the fluctuating behaviour of variable renewable energy sources. The environmental sustainability of energy storage technologies should be carefully assessed, together with their techno-economic feasibility. In this work, an environmental analysis of a renewable hydrogen-based energy storage system has been performed, making use of input parameters made available in the framework of the European REMOTE project. The analysis is applied to the case study of the Froan islands (Norway), which are representative of many other insular microgrid sites in northern Europe. The REMOTE solution is compared with other scenarios based on fossil fuels and submarine connections to the mainland grid. The highest climate impacts are found in the diesel-based configuration (1,090.9 kgCO2eq/MWh), followed by the REMOTE system (148.2 kgCO2eq/MWh) and by the sea cable scenario (113.7 kgCO2eq/MWh). However, the latter is biased by the very low carbon intensity of the Norwegian electricity. A sensitivity analysis is then performed on the length of the sea cable and on the CO2 emission intensity of electricity, showing that local conditions have a strong impact on the results. The REMOTE system is also found to be the most cost-effective solution to provide electricity to the insular community. The in-depth and comparative (with reference to possible alternatives) assessment of the renewable hydrogen-based system aims to provide a comprehensive overview about the effectiveness and sustainability of these innovative solutions as a support for off-grid remote areas
Online measurements of fluoride ions in proton exchange membrane water electrolysis through ion chromatography
No full textThis work investigates the online monitoring of fluoride ion concentration in proton exchange membrane water electrolysers (PEMWE) effluent water using an automated ion chromatography (IC) setup. Prototype catalyst coated membranes (CCMs) with different thicknesses have been tested and fluoride measurements under different operating conditions at both single cell and stack level have been carried out. The study reports the impact of both current density and temperature on the cathodic fluoride concentrations showing a maximum at low current densities, at around 0.4 A/cm2 for the single cells, and at 0.2–0.4 A/cm2 for the short stack. It is also reported that higher PEMWE working temperature has an adverse effect on the membrane stability, resulting in a significant increase of the fluoride release at the cathode outlet. Noticeably, CCMs with reduced membrane thickness exhibited lower values of area-specific fluoride release rates with respect to thicker CCMs. Finally, the study also reports that fluoride concentrations and water conductivity are very well correlated, displaying a linear correlation. This new finding could represent a low cost and straightforward method to obtain quantitative information about membrane degradation rates in larger commercial PEMWE systems
A study of the techno-economic feasibility of H2-based energy storage systems in remote areas
No full textThe development of efficient and sustainable energy solutions and the attempt to reduce carbon dioxide emissions are leading to an increasing penetration of Renewable Energy Sources (RES). Effective Electrical Energy Storage (EES) solutions need therefore to be developed to deal with the issue of fitting locally available RES and loads. Hydrogen can become an interesting option because of its high energy density, long-term storage capability and modularity. In particular, in isolated micro-grid and off-grid remote areas, intermittent RES integrated with H2-based storage systems can allow to lower, or even eliminate, the usage of diesel engines and avoid the need for expensive and invasive grid connections. The present study is part of the European REMOTE project, whose main goal is to prove the added value of H2-based energy storage solutions with respect to alternative technologies in terms of economics, technical and environmental benefits. Four demonstration sites supplied by renewable electricity will be installed in either isolated micro-grids or off-grid remote areas throughout all Europe, from Italy (two sites) and Greece to Norway. The aim of this work is to perform a techno-economic analysis and demonstrate the effectiveness of the hybrid H2-battery Power-To-Power (P2P) solution in reducing the usage of external sources (e.g., diesel engines or grid) in a cost-effective way, with different load and environment conditions. The economic viability of the considered scenarios was outlined by computing the Levelized Cost Of Energy (LCOE). For each of the four sites, the innovative renewable configuration was compared with the current/alternative one. The REMOTE project partners provided main input data for the analysis: techno-economic data from the technology suppliers, whereas electricity consumption and RES production values from the end users of the four isolated locations. LCOE values derived using cost inputs both from REMOTE and literature are presented for a comparison. Results from the energy simulations revealed that the need for an external source is significantly reduced thanks to RES together with the hybrid storage system. Moreover, for all the four sites the renewable solution was shown to be more profitable than the current or alternative one, either in the short term or in the longer term
Multiple isolated spinal aneurysms – A rare condition with uncertain treatment strategies: A case report and literature review
No full textPurpose: Isolated spinal aneurysms (iSAs) are rare, with an uncertain natural history and no established treatment guidelines. Multiple iSAs are even more uncommon, complicating treatment decisions. Methods: This study reports a case of a ruptured radiculo-pial artery aneurysm in a patient with multiple iSAs, treated with surgical excision, assisted by intraoperative neurophysiological monitoring (IONM). Further, we review and analyze all previously reported cases of multiple iSAs. Results: A 67-year-old woman with spinal subarachnoid hemorrhage and spinal cord compression due to a ruptured radiculo-pial artery aneurysm was treated surgically. Digital subtraction angiography (DSA) showed three spinal aneurysms. Intraoperative indocyanine green video-angiography (ICG-VA) revealed an aneurysm contributing to the left posterior spinal artery. The aneurysm was excised after proximal inflow occlusion under IONM. The other aneurysms spontaneously regressed, and the patient had a good functional outcome. Through a systematic literature review, we analyzed 13 multiple iSAs including our case, involving 34 aneurysms in total. Conclusions: There is no standardized treatment approach for multiple iSAs. These aneurysms are often fusiform and clustered in contiguous metameric regions. They can be classified into flow-related and wall-weakening aneurysms. Surgery offers definitive treatment for ruptured iSAs and relieves spinal cord compression. Due to the common fusiform shape, parent vessel sacrifice may be necessary, and should include IONM and ICG-VA to minimize complications. Conservative treatment is viable as spontaneous regression often occurs
The comparison of outcome after arthroplasty or fusion in single level cervical disc disease
No full textMagnetic resonance imaging evaluation after implantation of a titanium cervical disc prosthesis: a comparison of 1.5 and 3 Tesla magnet strength
No full textPurpose Cervical disc prostheses induce significant amount of artifact in magnetic resonance imaging which may complicate radiologic follow-up after surgery. The purpose of this study was to investigate as to what extent the artifact, induced by the frequently used Discover® cervical disc prosthesis, impedes interpretation of the MR images at operated and adjacent levels in 1.5 and 3 Tesla MR.
Methods Ten subsequent patients were investigated in both 1.5 and 3 Tesla MR with standard image sequences one year following anterior cervical discectomy with arthroplasty.
Outcome measures Two neuroradiologists evaluated the images by consensus. Emphasis was made on signal changes in medulla at all levels and visualization of root canals at operated and adjacent levels. A “blur artifact ratio” was calculated and defined as the height of the artifact on T1 sagittal images related to the operated level.
Results The artifacts induced in 1.5 and 3 Tesla MR were of entirely different character and evaluation of the spinal cord at operated level was impossible in both magnets. Artifacts also made the root canals difficult to assess at operated level and more pronounced in the 3 Tesla MR. At the adjacent levels however, the spinal cord and root canals were completely visualized in all patients. The “blur artifact” induced at operated level was also more pronounced in the 3 Tesla MR.
Conclusions The artifact induced by the Discover® titanium disc prosthesis in both 1.5 and 3 Tesla MR, makes interpretation of the spinal cord impossible and visualization of the root canals difficult at operated level. Adjusting the MR sequences to produce the least amount of artifact is important.
© The Author(s) 2013 Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited
A Novel Combination of Methods Developed for Decision Support on Abatement of Mercury in Europe
No full textThere is clear evidence from the global mercury cycle that there is an urgent need for actions to reduce global anthropogenic mercury emissions. A legally- binding global agreement to reduce emissions of mercury is soon in place, meaning that many countries need to take steps to lower their emissions. Identification and assessment of policy options that already are in place as well as setting pollution control objectives and developing effective strategies to meet these objectives, are depending on a decision support tool that allows for identifying current and future environmental problems and to reduce these problems by providing a holistic management approach. Recent scientific advancement allows a more complete picture of the mercury problems and solutions to the problems, which is of outmost interest when it comes to justifying spending resources on the relevant measures. To make sure that resource allocation is favoring human welfare, the economic costs of introducing these measures need to be compared to their economic benefits. The major goal of this study was to provide a novel combination of assessment tools that form a framework for a decision support system towards environmental policy on mercury in Europe. The decision support tool was intended to act as a guideline for policy makers for the purpose of introducing cost- effective abatement of mercury. It was for the EU 27 countries demonstrated that large economic benefits can be achieved globally with reduced mercury emissions in the EU region. The investigated Baseline scenario thus highlighted the importance of full implementation of existing measures and the importance of making further progress in reducing mercury emissions from European sources. Reducing emissions in developing countries may however, be more cost effective, which basically reconfirms the need for a global convention on mercury
Air quality and human welfare
No full textHuman welfare is generally referring to allocation of resources to fit the well being of humans. If high standard of well-being is to be maintained, the concerns for a healthy environment must be balanced against requirements of economic growth. In a natural capital system, human welfare is best served by improving the quality and flow of desired services delivered rather than merely increasing the total money flow. An ecosystem based management of living and natural resource use will steer this progress to the best of human welfare while the efficiency of ecosystem based management depends strongly on the availability of integrated assessment tools that will combine environmental models and monitoring data with ecological economic valuation methods. In applied welfare economics, the methodological approach to assess resource allocations towards societal optimality and thereby establish criteria for government intervention is often linked to tools as Cost-ffectiveness Analysis (CEA), Cost-Benefit Assessment (CBA) or Multi-criteria Analysis (MCA). By illustrating an assessment on costs and benefits of the implementation of Hg emission reduction measures in the coal sector, it becomes obvious that for a full analysis of societal costs and benefits, several aspects of Hg pollution, sources, impacts and co-benefits need to be considered
Development of a PC-Based System for Recording Flash Electroretinograms in Experimental Animals
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