Promotion of wind energy in isolated energy systems: The case of the Orites wind farm

With the establishment of the first wind farm on the island, Cyprus has made progress to satisfy the European Union's 2020 renewable energy targets. Operational since September 2010, the 174 M€ Orites wind farm is currently the largest wind project in the Mediterranean region. In this article, the main characteristics of the project with regard to Cyprus's national action plan for the promotion of renewable energy sources are presented. The socio-economic impacts of the project and its feasibility in the context of an isolated energy system are also examined. The results of a public survey to identify the attitudes of surrounding households and neighbouring cities towards the wind farm are presented. The assessment was based on face-to-face interviews conducted with 50 households from the surrounding communities and 100 interviewees from neighbouring cities. According to the survey, the public opinion on the wind farm was generally positive, and the majority of the respondents considered the wind farm to be acceptable as of no considerable environmental impact

CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area: Evaluation using “air delay”

Outdoor urban ventilation in a real complex urban area is investigated by introducing a new ventilation indicator – the “air delay”. Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The up-to-date literature shows the lack of detailed evaluations of the two approaches for real compact urban areas. This study further presents a systematic evaluation of steady RANS and LES for the assessment of the ventilation conditions in a dense district in Nicosia, Cyprus. The ventilation conditions within the urban area are investigated by calculating the distribution of the age of air. To better assess the outdoor ventilation, a new indicator, the “air delay” is introduced as the difference between the local mean age of air at an urban area and that in an empty domain with the same computational settings, allowing the comparison of the results in different parts of the domain, without impact of the boundary conditions. CFD results are validated using wind-tunnel measurements of mean wind speed and turbulence intensity performed for the same urban area. The results show that LES can accurately predict the mean wind speed and turbulence intensity with the average deviations of about 6% and 14%, respectively, from the wind-tunnel measurements while for the steady RANS, these are 8% and 31%, respectively. The steady RANS simulations overestimate the local mean air delay. The deviation between the two approaches is 52% at pedestrian level (2 m).status: publishe

Spatio-temporal variability of desert dust storms in Eastern Mediterranean (Crete, Cyprus, Israel) between 2006 and 2017 using a uniform methodology

The characteristics of desert dust storms (DDS) have been shown to change in response to climate change and land use. There is limited information on the frequency and intensity of DDS over the last decade at a regional scale in the Eastern Mediterranean. An algorithm based on daily ground measurements (PM10, particulate matter ≤10 μm), satellite products (dust aerosol optical depth) and meteorological parameters, was used to identify dust intrusions for three Eastern Mediterranean locations (Crete-Greece, Cyprus, and Israel) between 2006 and 2017. Days with 24-hr average PM10 concentration above ~30 μg/m3 were found to be a significant indicator of DDS for the background sites of Cyprus and Crete. Higher thresholds were found for Israel depending on the season (fall and spring: PM10 > 70 μg/m3, winter and summer: PM10 > 90 μg/m3). We observed a high variability in the frequency and intensity of DDS during the last decade, characterized by a steady trend with sporadic peaks. The years with the highest DDS frequency were not necessarily the years with the most intense episodes. Specifically, the highest dust frequency was observed in 2010 at all three locations, but the highest annual median dust-PM10 level was observed in 2012 in Crete (55.8 μg/m3) and Israel (137.4 μg/m3), and in 2010 in Cyprus (45.3 μg/m3). Crete and Cyprus experienced the same most intense event in 2006, with 24 h-PM10 average of 705.7 μg/m3 and 1254.6 μg/m3, respectively, which originated from Sahara desert. The highest 24 h-PM10 average concentration for Israel was observed in 2010 (3210.9 μg/m3) during a three-day Saharan dust episode. However, a sub-analysis for Cyprus (years 2000-2017) suggests a change in DDS seasonality pattern, intensity, and desert of origin. For more robust conclusions on DDS trends in relation to climate change, future work needs to study data over several decades from different locations

Dispersion Experiments in Central London: The 2007 DAPPLE project

In the event of a release of toxic gas in the center of London, the emergency services would need to determine quickly the extent of the area contaminated. The transport of pollutants by turbulent flow within the complex street and building architecture of cities is not straightforward, and we might wonder whether it is at all possible to make a scientifically-reasoned decision. Here we describe recent progress from a major UK project, ‘Dispersion of Air Pollution and its Penetration into the Local Environment’ (DAPPLE, www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London (UK) during 2003, 2004, 2007, and 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because (i) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft, (ii) measurements were made under a wide variety of meteorological conditions, and (iii) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data