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The Severn Estuary has the world's second largest tide range and a barrage across the estuary, located just seawards of Cardiff in Wales and Weston in the South West England, has been proposed for over half a century, with the objective of extracting large amounts of tidal energy. A Severn Barrage, as previously proposed by the Severn Tidal Power Group (STPG), would be the largest renewable energy project for tidal power generation in the world, if built as proposed, and would generate approximately 5% of the UK's electricity needs. However, concerns have been raised over the environmental impacts of such a barrage, including potential increase in flood risk, loss of intertidal habitats etc. In addressing the challenges of maximizing the energy output and minimizing the environmental impacts of such a barrage, this research study has focused on using a Continental Shelf model, based on the modified Environmental Fluid Dynamics Code (EFDC) with a barrage operation module (EFDC_B), to investigate both the far and near field hydrodynamic impacts of a barrage for different operating scenarios. Three scenarios have been considered to simulate the Severn Barrage, operating via two-way generation and using different combinations of turbines and sluices. The first scenario consisted of 216 turbines and 166 sluices installed along the barrage; the second consisted of 382 turbines with no sluices; and the third consisted of 764 turbines and no sluices. The specification of the sluice gates and turbines are the same for all scenarios. The model results indicate that the third scenario has the best mitigating effects for the far-field and near-field flood risks caused by a barrage and produces the most similar results of minimum water depth and maximum velocity distributions to those obtained from simulating the natural conditions of the estuary, i.e. the current conditions. The results also show that the flow patterns around the barrage are closest to those for the existing natural conditions with minimal slight changes in the estuary. Thus, the results clearly indicate that the environmental impacts of a Severn Barrage can be minimized if the barrage is operated for two-way generation and under the third scenario. Although it appears that the energy output for the third scenario is less than that obtained for the other two scenarios, if very low head (VLH) turbines are used, then the third scenario could generate more energy as more turbines could be cited along the barrage structure. Therefore, the study shows that a Severn Barrage, operating in two-way generation and with 764 turbines (ideally VLH turbines), would be the best option to meet the needs of maximizing the energy output, but having a minimal impact on environmental changes in the estuary and far-field.

Climate change and limited availability of fossil fuel reserves stress both the importance of deploying renewable energy sources (RES) for electricity generation and the need for a stronger integration of regional electricity markets. This analysis focuses on North African (NA) countries, which possess vast resources of renewable energy but whose electricity supply is still largely dependent on fossil fuels. An analysis of cost-optimized deployment scenarios for RES is conducted in five NA countries in 2030 and 2050. Three electricity models are combined to derive results covering trans-regional to sub-national level, including a detailed analysis of grid capacities and future transmission challenges. Further, opportunities for integration of European and NA electricity markets are evaluated. Results confirm that, by 2050, high RES shares – close to 100% – are possible in NA. Wind energy is the dominant technology. Concentrated Solar Power (CSP) plants also play an important role with rising RES shares due to the possibility to store thermal energy. Electricity exports to Europe gain particular importance in the period after 2030. Substantial transmission grid reinforcements on AC-level and the construction of a high voltage DC overlay grid are prerequisites for the forecasted scenarios.

This paper discusses an overall strategy for reducing energy demand in non-domestic buildings, mainly focusing on office developments. It considers four areas: reducing internal heat loads; addressing passive design through the building construction; using efficient and responsive HVAC systems and focusing on chilled (heated) surface systems; integrating renewable energy supply systems into the building design. The impact on energy use and carbon dioxide emissions will be discussed. The paper will draw from a range of design projects carried out in Europe, where this integrated approach has been applied, and then explore the benefits in relation to applications in the Middle East and China. Energy modelling results, to inform the design process will be presented, using energy simulation for three case study locations, in Zurich, the Chongqing and Abu Dhabi.

AbstractWe look at the variability of the power produced by the three-float M4 wave energy converter for locations in the North-East Atlantic and North Sea using the NORA10 hindcast data from 1958−2011. The aim is to investigate whether the produced power is also strongly affected by the climate variability (such as the North Atlantic Oscillations) in the winter, just as the ocean wave power resource as observed in previous studies. In this study, we demonstrate the use of proxy indices in combination with the climate indices to reconstruct a historic practical wave power climate from 1665−2005. We also conduct sensitivity studies to assess the changes in the practical wave power variability in response to perturbing the machine size, the power take-off coefficient, the response bandwidth and the power limit of the power take off. We find that the resultant temporal variation is still dominated by the climate variability. However, the overall variability important for power availability and energy supply economics is smaller than that of the ocean wave power resource because of the finite capture bandwidth of the M4 machine. The statistical methodology presented here is also potentially relevant to other wave energy converters in similar locations.

Abstract Consumers can choose from a wide range of electricity supply contracts, including green power options. Electricity produced from renewable energy involves information asymmetries. With a sample of more than 2,000 German electricity consumers, we tested the proposition of a “lemon market” for renewable energy in a discrete choice experiment. Specifically, we found that, compared to investor-owned firms, additional willingness-to-pay for renewable energy is approximately double when offered by cooperatives or municipally-owned electricity utilities. Consumers who are experienced with switching suppliers have an additional willingness-to-pay of one Eurocent per kilowatt hour for cooperatives and two Eurocents for public enterprises. The results demonstrate that organizational transformation in dynamically-changing electricity markets is not only driven by political initiatives but also by consumers' choices on the market. Public policy may reduce information asymmetries by promoting government labeling of green energy products.

AbstractAmongst academics and practitioners working in the fields of urban planning and design, there has been an on-going discussion regarding the relationships between urban morphology and environmental sustainability. A main focus of analysis has been to investigate whether the form of cities and neighbourhoods can be related to their energy efficiency, especially regarding the energy intensity of buildings and transportation. However, to analyse the overall energy performance of urban systems, both the consumption and the generation of resources need to be assessed. In terms of urban environmental sustainability, the potential to generate renewable energy within the city boundaries is a research topic of growing interest, being solar energy one of the main resources available.This study uses neighbourhood-scale statistical models to explore the relationships between aggregated urban form descriptors and the potential to harvest solar energy within the city. Different possible scenarios of urban morphology in Greater London are analysed and variables of urban form are tested with the aim of increasing the solar energy potential of neighbourhoods. Results show that by optimising combinations of up to eight variables of urban form the solar irradiation of roofs could be increased by ca. 9%, while that of façades could increase by up to 45%. Furthermore, based on these results, a series of trade-offs needed for the optimisation of conflicting variables is unveiled. Finally, some recommendations for design strategies are offered with the aim of helping urban planners and designers improve the solar energy potential of new or existing urban areas.

Abstract Wind energy development is booming worldwide with Germany and the United States being forerunners in installed capacity. Based on a review of relevant laws and regulations, policy, siting, and permitting documents, academic literature, and expert interviews, the paper compares the permit and environmental impact assessment (IA) policies and regulations pertaining to wind energy projects in both countries. The focus is on the potential of IAs in supporting an environmentally conscious development of wind power generation. This includes the analysis of IA regulations on the project level, strategic level impact assessment and planning processes, opportunities for public involvement and transparency of processes, and the clarity and predictability of the IA provisions. The findings suggest certain variations between both countries' permit and IA processes for wind energy projects and further research needs, inter alia on the actual effects of strategic assessment of wind development on subsequent permitting.

The adoption of solar photovoltaic (PV) technologies has expanded rapidly in recent years, leading to suggestions that this growth, which occurred mostly in high-latitude countries with often low levels of sunshine, may have come at an unnecessarily high price. However, the factors influencing the cost of solar PV, and the subsidies required to sustain its uptake, include more than just the level of sunshine. While cross-country differences in technology costs are hard to ascertain, it is possible to account for the cost of capital on a country-by-country basis. In this paper, we therefore map the cost of solar PV globally, accounting for differences in both the solar resource and the financing cost in order to calculate the levelized cost of electricity (LCOE) from solar PV systems in 143 countries. In contrast to the work of other researchers who typically treat financing costs as uniform across countries, our results suggest that the LCOE of solar PV systems in northern countries may in fact be lower than in equatorial countries, and high latitude countries may thus not have been an unwise location to subsidize the adoption of solar PV technologies in the past. Our results further suggest that efforts to expand PV installation in equatorial developing countries may benefit greatly from policies designed to make low cost finance more widely available, which underlines on-going efforts to “de-risk” low carbon investments.