Assessing wave energy effects on biodiversity: the wave hub experience

Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.     

Green energy?

The UK gets nearly all its energy from the fossil fuels (coal, oil, gas etc.) and nuclear power, approximately 15% being consumed in the form of electricity. It is now well known that the burning of fossil fuels is accompanied by atmospheric pollution in the form of acid rain, ozone depletion and the greenhouse effect. Renewable energy sources, e.g. wind, solar, tidal, wave, hydroelectric and geothermal power do not at present contribute significantly to the UK energy supply and are also accompanied by adverse effects on the environment. The best hope for meeting future energy needs may lie in containing energy consumption, increased generation efficiency and an expanded nuclear power programme. The author discusses the problems of acid rain and the greenhouse effect and describes several forms of renewable energy: wind energy, solar energy, tidal power, wave power, hydroelectricity, biomass geothermal power and nuclear power     

Electricity generation: options for reduction in carbon emissions

Historically, the bulk production of electricity has been achieved by burning fossil fuels, with unavoidable gaseous emissions, including large quantities of carbon dioxide: an average-sized modern coal-burning power station is responsible for more than 10 Mt of CO(2) each year. This paper details typical emissions from present-day power stations and discusses the options for their reduction. Acknowledging that the cuts achieved in the past decade in the UK CO(2) emissions have been achieved largely by fuel switching, the remaining possibilities offered by this method are discussed. Switching to less-polluting fossil fuels will achieve some measure of reduction, but the basic problem of CO(2) emissions continues. Of the alternatives to fossil fuels, only nuclear power represents a zero-carbon large-scale energy source. Unfortunately, public concerns over safety and radioactive waste have still to be assuaged. Other approaches include the application of improved combustion technology, the removal of harmful gases from power-station flues and the use of waste heat to improve overall power-station efficiency. These all have a part to play, but many consider our best hope for emissions reduction to be the use of renewable energy. The main renewable energy contenders are assessed in this paper and realistic estimates of the contribution that each could provide are indicated. It appears that, in the time-scale envisaged by planners for reduction in CO(2) emission, in many countries renewable energy will be unlikely to deliver. At the same time, it is worth commenting that, again in many countries, the level of penetration of renewable energy will fall short of the present somewhat optimistic targets. Of renewable options, wind energy could be used in the short to medium term to cover for thermal plant closures, but for wind energy to be successful, the network will have to be modified to cope with wind's intermittent nature. Globally, hydroelectricity is currently the largest developed source of renewable electricity, but future large-scale projects will probably be limited to the less-developed world: the best schemes in the developed countries have already been exploited. Wave and tidal can be looked on as medium- to long-term generators of electricity, as their respective industries are not as mature as competing renewable resources. Municipal solid-waste combustion and landfill gas technologies can also be seen as short term, as can their rural equivalents, agriculture and forestry waste. Any widespread exploitation of renewable energy will depend on being able to transmit the energy from source to point of use, so the implications for the electrical network from the penetration of substantial levels of renewable energy are presented. Effective management of renewable energy installations will require technical assessment of the range of exploitation strategies, to compare local production of, say, hydrogen and the more traditional transmission of electricity. Such resources will have to compete with others in any national, or grid, system and detailed economic analysis will be necessary to determine the deployment that best fits the trading regime under which the energy will be sold. Consideration will also be necessary to determine how best to control the introduction of this radically new resource such that it does not attract punitive cost overheads until it is mature enough to cope. Finally, it is inescapable that nuclear power is a proven technology that could take its place in any future generation portfolio. Unfortunately, suspicion and mistrust surround waste management and radioactivity release. Unless this is overcome, the lack of confidence engendered by this public mistrust may result in few, if any, new nuclear power stations being built. In the event of that decision, it is difficult to see how CO(2) levels can be significantly reduced: the irony is that nuclear energy may emerge as environmentally essential.     

Flood risk management in the Thames Estuary looking ahead 100 years

The River Thames tidal defences have provided protection against the increasing threat of tidal flooding from the North Sea for more than 2000 years. The flood of 1953 was the catalyst for the construction of the current system of River Thames tidal defences, which includes the Thames Barrier, and has provided one of the best standards of flood defence in the UK for over 20 years. Substantial growth is planned through "Thames Gateway", a regeneration initiative of the United Kingdom government. These new developments will fundamentally change the developed footprint in the Thames Estuary flood-plain, and will be in place for at least the next 100 years. This presents a challenge of planning future defence against a background of uncertainty over climate and other environmental change, while ensuring that correct decisions are made concerning the nature and location of new building in the tidal flood-plain. Through its "Thames Estuary 2100" project, the Environment Agency is developing a long-term strategy for flood risk management in the estuary. Implementation of major construction works on the River Thames could commence from around 2015. Alternatively, it may be decided that minimum works are undertaken to provide security and major investment is delayed until uncertainties over climate change have abated. Whatever long-term option is chosen, this must be preceded by a period of collaboration with the Thames Gateway developments to ensure appropriate and sustainable flood defences are incorporated in new riverside construction.     

Developing a multivariate manufacturing company performance model: Effects of technology and investment on two-dimensional firm performance

The research aims to make a methodological contribution to the field of manufacturing practice-performance relationship studies by researching the relationships between cumulative investment, technology usage and two-dimensional performance measures in particular. A multivariate regression model has been developed to test the relationships and to explore the utility of the model. A UK cross-sectional manufacturing database covering a long period has been used to test the developed multiple outputs model. The conclusions are given on the relationships between these factors and are also generalized to define the useful contribution that such models make to the theory development for relationship studies and the possible benefits to practitioners.     

Decoding the energy landscape: extracting structure, dynamics and thermodynamics

Describing a potential energy surface in terms of local minima and the transition states that connect them provides a conceptual and computational framework for understanding and predicting observable properties. Visualizing the potential energy landscape using disconnectivity graphs supplies a graphical connection between different structure-seeking systems, which can relax efficiently to a particular morphology. Landscapes involving competing morphologies support multiple potential energy funnels, which may exhibit characteristic heat capacity features and relaxation time scales. These connections between the organization of the potential energy landscape and structure, dynamics and thermodynamics are common to all the examples presented, ranging from atomic and molecular clusters to biomolecules and soft and condensed matter. Further connections between motifs in the energy landscape and the interparticle forces can be developed using symmetry considerations and results from catastrophe theory.     

Competition between recovery and recrystallization in two tungsten supplies according to ITER specifications

In thermonuclear fusion devices, tungsten, implemented as armour material of plasma facing components, is in direct contact with the plasma. Due to high heat flux (20 MW/m\(^{2}\) ), a premature cracking can be observed in relation with the loss of tungsten mechanical properties. It is usually attributed to two competing restoration processes: recovery and recrystallization. A recent investigation on two tungsten supplies according to ITER specifications has highlighted that hardness abatement at high temperature leads to overestimate the recrystallization fraction, which may be a consequence of the significant contribution of recovery during annealing. The present article aims at investigating this phenomenon through the use of a dedicated mean field recrystallization model that, unlike JMAK models, accounts for physical parameters at the microstructure scale such as recovery parameter or grain boundary mobility. The methodology is applied on the two tungsten supplies for ITER. It allows discriminating, for the first time, the respective contributions of recovery and recrystallization to the macroscopic softening in the high temperature range (from 1450 to \(1800\,^{\circ }{\text {C}}\)) and annealing times (0–3500 s). The approach has led to the conclusions that the two supplies merely differ from their initial (delivery) state through the stored energy, the initial recrystallized fraction and the grain size but not from intrinsic physical parameters such as recovery parameter or grain boundary mobility.

     

Fabrication–microstructure–performance relationships of reversible solid oxide fuel cell electrodes–review

Abstract

A reversible solid oxide fuel cell system can act as an energy storage device by storing energy in the form of hydrogen and heat, buffering intermittent supplies of renewable electricity such as tidal and wave generation. The most widely used electrodes for the cell are lanthanum strontium manganate–yttria stabilised zirconia and Ni–yttria stabilised zirconia. Their microstructure depends on the fabrication techniques, and determines their performance. The concept and efficiency of reversible solid oxide fuel cells are explained, along with cell geometry and microstructure. Electrode fabrication techniques such as screen printing, dip coating and extrusion are compared according to their advantages and disadvantages, and fuel cell system commercialisation is discussed. Modern techniques used to evaluate microstructure such as three-dimensional computer reconstruction from dual beam focused ion beam–scanning electron microscopy or X-ray computed tomography, and computer modelling are compared. Reversible cell electrode performance is measured using alternating current impedance on symmetrical and three electrode cells, and current/voltage curves on whole cells. Fuel cells and electrolysis cells have been studied extensively, but more work needs to be done to achieve a high performance, durable reversible cell and commercialise a system.     

Towards sustainable photovoltaics: the search for new materials

The opportunities for photovoltaic (PV) solar energy conversion are reviewed in the context of projected world energy demands for the twenty-first century. Conventional single-crystal silicon solar cells are facing increasingly strong competition from thin-film solar cells based primarily on polycrystalline absorber materials, such as cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). However, if PVs are to make a significant contribution to satisfy global energy requirements, issues of sustainability and cost will need to be addressed with increased urgency. There is a clear need to expand the range of materials and processes that is available for thin-film solar cell manufacture, placing particular emphasis on low-energy processing and sustainable non-toxic raw materials. The potential of new materials is exemplified by copper zinc tin sulphide, which is emerging as a viable alternative to the more toxic CdTe and the more expensive CIGS absorber materials.     

物理学与中国能源可持续发展——献给2005世界物理年

物理学与工程技术有着密切的相互联系，能源工程技术与物理学的关系具有典型的代表性，物理学的应用可以对我国能源事业的发展做出重要的贡献。文章着重阐述了原子核物理学和核能工程（包括裂变核能和聚变核能），光电效应与光伏发电，风能、生物质能与物理学，物理化学与煤的多联产、洁净化技术，地球物理学与能源资源勘探等能源问题；讨论了物理学在节能中的三个应用：节能照明、建筑节能和交通节能；分析了中国能源的可持续发展前景     

Intricacies of medical drones in healthcare delivery: Implications for Africa

Unmanned aerial vehicles, also known as drones, can play a critical role in delivering health care. In this paper, we reviewed the literature to ascertain (1) the various medical supplies delivered by drones, (2) the challenges to the successful use of medical drones and (3) the potential benefits of medical drones. Implications for the African context is then provided. In achieving this objective, we employed a systematic literature review methodology and defined search strings, searched for relevant literature from PubMed, Scopus and Web of Science databases following a review protocol. The snowball technique was similarly used to search for other papers as well. A total of 17 out of 69 papers were included in the review after screening and applying a quality appraisal criterion. The results indicate that blood, AEDs, drugs, vaccines, and laboratory test samples etc were identified as part of the medical supplies aerially delivered by drones. Regulations, cost, misuse (evasion of people's privacy) and psychological effect on people who experienced drones used for bombing are part of the challenges that could result from using the technology for delivery of medical supplies. The benefits derived from drones range from reducing response times during health emergencies thus helping to save more lives, to being environmentally friendly as the CO₂ emissions levels are lower than conventional delivery by trucks and cars. In conclusion, drone technology has opened a new phase for the health sector and to sustain this technological innovation in Africa, there is the need for inclusive innovation to make drones safer and acceptable. This could be achieved by developing the needed policy framework with the regulators, providing other health resources to complement the use of drones, embarking on sensitizations on the usefulness of drones through cultural underpinnings of rural communities about drones and training the needed health personnel to handle dispatches of medical supplies with drones.     

The potential of biomass supply for energetic utilization in a small Italian region: Basilicata

The European Union Directive 2009/28/EC (European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing directives 2001/77/EC and 2003/30/EC, Directive 2009/28/EC) establishes a common framework for the use of energy from renewable sources in order to reduce both greenhouse gas emissions and reliance on fossil fuels from foreign markets; more specifically the EU has the ambitious goal of reaching a 20 % share of energy from renewable sources in the overall energy mix by 2020. These objectives could drive policies that offer substantial economic subsidies for the use of renewable energy, both in Italy and in many other European countries. For all these reasons, biomass (one of the major sources of renewable energy) plants are getting a lot of attention in Italy, but it is necessary to determine whether using of this type of energy is environmentally beneficial and economically feasible. In this study, we evaluate the energy and so the environmental aspects by considering both current and potential biomass supplies available for energy utilization in a small region in the South of Italy: Basilicata, as well as the consequences of this energy conversion at both the local and the global scale.     

Development of test methodologies for experimental lifetime investigations of tidal turbines

As a regenerative energy source, tidal energy can significantly contribute to greenhouse gas reduction, even though the potentially achievable energy output is lower than that of wind or solar energy. The decisive advantage of tidal turbines lies in the simply and reliably predictable energy output. However, their commercial use has so far been impeded by the fact that on the one hand complex mechanical systems are required to convert energy of tidal currents and on the other hand multi-axial loading conditions caused by turbulent ocean currents act on the turbine. For this reason, field tests on prototypes are an essential part of the development strategy to ensure operational reliability. However, in-field tests do not allow for accelerated lifetime testing, so that test bench experiments are becoming an increasingly important alternative. Today, established procedures for testing the turbines main bearings and gearing system are already available, both for setting up the required test configuration and for determining the corresponding test loads. However, the use of advanced calculation methods, such as the finite element method for stress calculation, requires a deep understanding of the examined components and hinders the transfer of the approaches to other components.

To simplify the process of test loads determination, a general methodology is presented, which relies exclusively on standardized empirical calculation rules. Doing this, fatigue equivalent loads can be determined for any component in a simple process. It was shown that the achieved reduction in complexity opens further potential for test acceleration, since several components can be tested simultaneously.

     

Optimal algorithm for constructing the embedded atom method potential for liquid metals

An optimal algorithm has been developed for calculating the embedding potential in the embedded atom method (EAM) with the aim of describing not only the temperature-dependent density of a liquid metal but also its energy up to its critical temperature. The algorithm is based on the unification of the form of the potential and calculation of its parameters from known density and energy data for the liquid metal. The basis of the algorithm is the use of least squares fitting of the pressure and energy in molecular dynamics simulations to data for a series of states of the liquid along an isobar. To describe liquid potassium, the pair contribution to the potential is represented by a power series in interparticle distance. Data on the properties of potassium at 343, 473, 723, 1000, 1500, 2000, and 2200 K were used. The embedding potential was expanded in terms of 1 − ρ, where ρ is the effective electron density in the EAM. In least squares fitting, fifteen equations were included: eight for the energy and seven for the pressure. The number of unknown coefficients was seven. Iterative calculations allow one to find optimal expansion coefficients and construct equilibrium models through molecular dynamics simulations. It is shown that the discrepancy in energy between simulations and the real metal at high temperatures can be eliminated by taking the electron excitation energy into consideration. The difference between the actual energy of a metal and the energy obtained in EAM simulations is very close to the contribution of the electron heat capacity.     

Modelling the perennial energy crop market: the role of spatial diffusion

Biomass produced from energy crops, such as Miscanthus and short rotation coppice is expected to contribute to renewable energy targets, but the slower than anticipated development of the UK market implies the need for greater understanding of the factors that govern adoption. Here, we apply an agent-based model of the UK perennial energy crop market, including the contingent interaction of supply and demand, to understand the spatial and temporal dynamics of energy crop adoption. Results indicate that perennial energy crop supply will be between six and nine times lower than previously published, because of time lags in adoption arising from a spatial diffusion process. The model simulates time lags of at least 20 years, which is supported empirically by the analogue of oilseed rape adoption in the UK from the 1970s. This implies the need to account for time lags arising from spatial diffusion in evaluating land-use change, climate change (mitigation or adaptation) or the adoption of novel technologies.     

Assessment of driving after stroke--a pluridisciplinary task

The aim of the study was to analyze the assessment procedure and identify predictors for the team decision when assessing fitness to drive a car after stroke. The material used was a retrospective data set with 200 stroke clients from Queen Elisabeth's Foundation Mobility Centre at Banstead UK. Fifty-four percent of clients were considered fit to continue driving where 9% could resume driving after car adaptation and training. Important factors for the outcome were vision (acuity and field), neuropsychological functions (divided attention), and track and/or on road test (reaction time, anticipation, speed, and positioning). Cognitive impairment was the main problem in those who failed the driving test and judged not fit for continued driving. Car adaptation, mainly comprising infrared transmitted secondary controls together with automatic transmission was recommended in 35% of the cases. CONCLUSIONS: The contribution of different specialist groups appears to be necessary for an effective evaluation, but the assessment procedure can be done more cost-effectively by dividing it into two separate parts and removing certain subtests. The in-car track test is an important part of the assessment procedure with a high face validity and could in many cases make it unnecessary to perform in-traffic tests with unsafe drivers. Car adaptation is often necessary for a client with pronounced hemi-paresis and a full road test can for those only be performed after training the use of car controls.     

Nuclear energy: current situation and prospects to 2020

For close to half a century nuclear fission has been providing reliable supplies of electricity to the UK, with virtually no emissions of carbon dioxide. Over that period, the UK nuclear industry has avoided the emission of over one and a half billion tonnes of CO2. Yet no nuclear plant has been built in the UK for over two decades even though many of the stations in our current fleet are now within a decade or so of the end of their lifetime. Without new plants being ordered soon, the UK's nuclear capacity will decline dramatically, from 23% today to 3% post-2020--just as considerations of supply security and climate change are becoming increasingly important. Elsewhere in the world, many countries such as China, India, Japan, South Korea, Finland and France are building new stations. Other countries such as the USA, South Africa, and some nations that currently do not have nuclear stations (such as Indonesia and Poland) are making preparations for future nuclear stations. Globally capacity factors for nuclear plants are higher than they have ever been, averaging around 85% and with the best stations achieving well over 90%. Lifetime can be 60 years. That the economics of such stations compete well with other technologies is well founded and easily verifiable--especially in the face of rising fossil fuel prices and the pricing in of costs for CO2 emissions--both of which stand to improve the economics of nuclear energy still further. Waste volumes arising from modern plants are just a fraction of those of some earlier stations, and the technologies are in place to deal with them safely and effectively. Following recent reviews and international developments, there is growing confidence that internationally available competitive designs of nuclear plant will provide part of the solution to the UK's long-term energy needs.     

不同热泵空调技术的对比

介绍了热泵技术的原理及分类,分别对空气源热泵、水源热泵、土壤源热泵、太阳能热泵空调系统的运行原理、特点、存在的问题及改进方法进行了分析;总结对比了这四种空调方式的优缺点,为不同地区选用热泵空调机组提供了参考依据。结论指出,通过合理热泵空调形式的应用,可以大大节约空调能耗,为我国节能减排工作做出重大贡献。     

Modelling approaches for coastal simulation based on cellular automata: the need and potential

The paper summarizes the theoretical and practical needs for cellular automata (CA)-type models in coastal simulation, and describes early steps in the development of a CA-based model for estuarine sedimentation. It describes the key approaches and formulae used for tidal, wave and sediment processes in a prototype integrated cellular model for coastal simulation designed to simulate estuary sedimentary responses during the tidal cycle in the short-term and climate driven changes in sea-level in the long-term. Results of simple model testing for both one-dimensional and two-dimensional models, and a preliminary parameterization for the Blackwater Estuary, UK, are shown. These reveal a good degree of success in using a CA-type model for water and sediment transport as a function of water level and wave height, but tidal current vectors are not effectively simulated in the approach used. The research confirms that a CA-type model for the estuarine sediment system is feasible, with a real prospect for coupling to existing catchment and nearshore beach/cliff models to produce integrated coastal simulators of sediment response to climate, sea-level change and human actions.     

On the activation energy of vacancies in solid helium

Contrary to existing theories, we have taken into account the fact that the effective potential between a pair of particles will be affected by the presence of a vacancy. This charge gives rise to a contribution to the activation energy which is of the same order of magnitude as the contribution due to the vacancy nonlocalization.