SOURCE TO TAP URBAN WATER CYCLE MODELLING

This work was supported by TRUST (TRansitions to the Urban Water Services of Tomorrow) research project.The continuous expansion of urban areas is associated with increased water demand, both for domestic and non-domestic uses. To cover this additional demand, centralised infrastructure, such as water supply and distribution networks tend to become more and more complicated and are eventually over-extended with adverse effects on their reliability. To address this, there exist two main strategies: (a) Tools and algorithms are employed to optimise the operation of the external water supply system, in an effort to minimise risk of failure to cover the demand (either due to the limited availability of water resources or due to the limited capacity of the transmission system and treatment plants) and (b) demand management is employed to reduce the water demand per capita. Dedicated tools do exist to support the implementation of these two strategies separately. However, there is currently no tool capable of handling the complete urban water system, from source to tap, allowing for an investigation of these two strategies at the same time and thus exploring synergies between the two. This paper presents a new version of the UWOT model (Makropoulos et al., 2008), which adopts a metabolism modelling approach and is now capable of simulating the complete urban water cycle from source to tap and back again: the tool simulates the whole water supply network from the generation of demand at the household level to the water reservoirs and tracks wastewater generation from the household through the wastewater system and the treatment plants to the water bodies. UWOT functionality is demonstrated in the case of the water system of Athens and outputs are compared against the current operational tool used by the Water Company of Athens. Results are presented and discussed: The discussion highlights the conditions under which a single source-to-tap model is more advantageous than dedicated subsystem models.Rozos, E.; Makropoulos, C. (2013). SOURCE TO TAP URBAN WATER CYCLE MODELLING. Environmental Modelling & Software. 41:139-150. https://doi.org/10.1016/j.envsoft.2012.11.0151391504

Mobility and Migrations in the Rural Areas of Mediterranean EU Countries

AbstractThis chapter focuses on the ambivalent nature of contemporary migrations in European rural areas. The growing presence of immigrants in these areas is a direct result of the restructuring of agriculture and global agri-food chains. Evidence indicates that while agricultural work and rural settings are decreasingly attractive to local populations, they represent a favourable environment to international newcomers, due to the higher chances to access livelihood resources. The non-visibility and informality that characterise rural settings and agricultural work arrangements provide on the one side opportunities for employment, while also fostering illegal labour practices and situations of harsh exploitation

Exergetic analysis and dynamic simulation of a solar-wind power plant with electricity storage and hydrogen generation

The ambitious vision of off-grid renewable energy autonomy of remote regions has yet to come to fruition. The development of comprehensive energy production systems would be needed to achieve such a goal. This study consists of the simulation and exergetic evaluation of a novel hybrid power plant for stand-alone operation aiming to provide electricity autonomy of a Mediterranean island. The considered power plant is simulated dynamically over an annual cycle and accounts for both energy input fluctuations and electricity surplus. The plant combines a photovoltaic array with wind turbines for energy input, coupled with electricity storage and a hydrogen generation facility to stabilize the power output of the plant. Unlike other similar studies, the energy system presented here relies on real-case weather and demand data of a relatively large remote community and is optimized to ensure continuous operation – even under extreme conditions. It is seen that this stand-alone hybrid power plant constitutes a robust and secure alternative to the current conventional energy situation; the combined renewable technologies succeed in complementing each other and offer stable performance throughout the year without the requirement of additional support by fossil fuels. The mean annual exergetic efficiency of the plant is found to be 17.9%, producing approximately 25,000 MWh of electricity per year, along with a secondary product (hydrogen) produced in the electrolyzer of the plant. Although this additional product is associated with additional investment cost, it offers the possibility to stabilize the power plant's performance and can be used as an additional source of financial income for the community.Fontina Petrakopoulou would like to thank the Universidad Carlos III de Madrid, the European Union's Seventh Framework Programme for Research, Technological Development and Demonstration (grant agreements n° 600371 and 332028), the Ministerio de Economía y Competitividad (COFUND2014-51509) and Banco Santander.Peer reviewe