• Energy Research
• UK Research and Innovation close
• 2008 close

Thermal energy storage is of critical importance in many engineering applications. The demand for CO2 reduction to curb global warming considerably increases the interest in utilizing renewable energy sources, especially solar energy. Due to the discrepancy between solar energy supply and energy demand, a thermal energy storage device has to be used. Thermal energy storage (TES) plays a vital role in solar energy applications in areas such as energy efficient buildings and solar power plants, and therefore, it has received significant attention. Thermal energy storage techniques can be classified as sensible heat storage and latent heat storage. Latent heat storage is particularly attractive, since it provides a high energy storage density and can store the energy as the latent heat of fusion at a constant temperature (phase change temperature of the corresponding PCMs). Although extensive investigations on low temperature latent heat storages mainly used for buildings have been conducted, very limited investigations on high temperature latent heat storages have been carried out for solar power plants. All the PCMs have a common problem of low thermal conductivity. The thermal conductivity is around 0.2 and 0.5 for paraffin and inorganic salts, respectively, which prolongs the charging and discharging period. Since metal foams have high thermal conductivities and high surface area density as well as good mechanical properties, they could be used as a metal skeleton embedded within PCMs to significantly enhance heat transfer both for low temperature and high temperature thermal storage systems reducing charge and discharge time. Most of PCMs undergo large change in volume (~10%) during melting. Volume contraction during solidification may not only reduce heat transfer area but also separate the PCM from the heat transfer surface, increasing the heat transfer resistance dramatically. But the presence of metal foams can quickly transfer heat through the structure surfaces embedded in the PCMs, and distribute the heat to the whole volume of PCMs from the heat transfer surface, thereby enhancing the heat transfer rate and reducing charge and discharge time. The energy storage mechanism in metal foams integrated with phase change materials (PCMs) is inherently complicated, since it involves solid/liquid phase change heat transfer, moving solid/liquid interface, porous metal foam microstructures, buoyancy induced natural convection etc.. Many underlying physical problems need to be understood, and all these warrant a detailed study for heat transfer enhancement of high temperature latent heat storages.The proposed research aims to experimentally and numerically study the feasibility of using metal foams to enhance the heat transfer capability of phase change materials (PCMs) in high temperature thermal energy storage systems used in solar power plants. The heat transfer enhancement caused by metal foam structures will be experimentally investigated. The effect of metal foam cell size and porosity on thermal energy storage will be examined. A numerical model will be developed to predict the complicated physical phenomena during the transient charging and discharging processes. Another major purpose of this collaborative research is to build the long-term concrete collaboration with one prestigious research group in China through the mutually interested research project. In this study, three inorganic PCMs: sodium nitrate (NaNO3), potassium nitrate, and an eutectic mixture of magnesium chloride, potassium chloride and sodium chloride (MgCl2/KCl/NaCl) will be employed as the latent heat storage materials. In this study, graphite foams will also be used for the experimental study, and the enhancing effect will be compared with the counterpart of metal foams (This work will be done by Xi'an Jiaotong University).

Develop an inifial specification for the turbine blades. We will develop a theorefical model for the composite structure based on conductive yarns of different impedance. Based on these models we will experimentally model the radar attenuation in the S-band and the X-band. The findings wili be validated using a DoE approach by producing small scale samples and measuring radar attenuation and comparing with theoretical findings. Based on the finding the models will be opfimised. • Flomerics - Develop and validate the initial EM modelling software solution. - Train consortium members in the use of the Flomerics software • Solent Composites -Involvement in setting the initial specification for the blades -Produce small scale composite samples • AMEC -Involvement in setting the initial specification for the blades • Pera - Modelling of the radar absorpfion of the composite structures -Testing of samples for radar attenuation (to be undertaken under sub-contract by organisation with large anechoic). Experimental invesfigafions will be undertaken using a DoE approach to determine the most appropriate yarns and conductive materials. Following a DoE approach, the yarns will be processed to give controlled conduction. The experiments will investigate co-mingled, coated and co-extruded yarns and the associated processing methods. The yarns be characterised to determine impedance and based on the findings, the materials and processes will be selected and optimised. • Oxley Threads - Develop a manufacturing process to create electrically conducfive yarns from conductive materials supplied by Hitek. • Hitek - Development and supply of the conducting materials for the conductive yarns that will later be used by Oxley Threads to produce the conducfive yarns. • Pera - Selection and modification of conductive materials and tesfing of materials for conductivity and mechanical behaviour. - Testing of conductive fibres for structure, conductivity and mechanical properties. - Testing of yams for conductivity and mechanical properties. The most appropriate conductive yarns from WP2 will be selected and base resins selected. A Jacquard 3D weaving process will be developed and optimised based on theoretical models developed in WPl. The pre-forms (with graded impedance) produced will be composites characterised for radar attenuation. Based on the results, the pre-form composite yarns and 3D structure will be optimised. • J&D Wilkie - Develop a 3D weaving technology that will allow us to create a textile structure made from yarns with different electrical conductivities that will enable us to create a textile with exponentially graded impedance through the z-axis. • Pera - Testing ofthe pre-forms for structure, mechanical behaviour, conductivity and radar attenuation. From the result of WP 1, 2 & 3, the optimal radar absorbing composite will be de signed and the 3D pre-forms will be manufactured on a lab-scale. The pre-form will be resin infused and metallic reflectors adhered to the back. The composite will be tested for radar attenuation and for mechanical performance and the composite structure (pre-form, resin and metallic reflectors) optimised. • Solent Composites - Develop a manufacturing process to enable the pre-form to be inserted into the blade mould, resin vacuum infusion of the pre-form and installation of the metallic backing sheet. - Testing ofthe blades for mechanical and other behaviour. • Hitek - Supply the conducfing materials forthe conductive yarns • Oxley Threads - Create electrically conductive yarns. . J&D Wilkie - Create textile structure. • Pera. - Testing of resin infused pre-form composites for structure, mechanical behaviour, conducfivity and radar attenuation. Fromthe result of WP 4, an optimised 3D pre-form will designed. The appropriate method of resin infusion will be determined. Tlie blade manufacturing process will be modified to allow the pre-form to be integrated during manufacture and then infused with resin to create a full scale turbine blade. The resultant blade structure will be tested and optimised for radar attenuation and mechanical properties. Tests for long term integrity will be started in this work package and may be completed after the end of the project to ensure we can achieve a 25 year useful lifetime including testing for the effects of lightening strikes. • Hitek - Supply the conducfing materials for the conducfive yarns - On-going management of long term integrity tests • Oxtey Threads - Create electrically conductive yarns • J&D Wilkie - Create textile structure. • Solent Composites - Produce full scale blade samples . AMEC - Provide end-user input and trial samples • Pera - Testing of samples for radar attenuation (to be undertaken under sub-contract by organisafion with large anechoic). - Testing of composites for structure, mechanical behaviour, conducfivity and radar attenuation. Application & exploitation of results, including development of an Exploitafion Strategy & protection of IPR. Hitek will be responsible for patents & exploitation and the other consortium partners will be responsible for exploitation of their parts of the technology & will participate in training & dissemination activities. Pera will undertake research and activities relating to technology transfer to the wider business community and development of wider business strategy in the form of workshop or the development of roadmaps. • Hitek leader - Exploitation and IPR protection activities. - Training and disseminafion activities - Patent applicafions - Development of Exploitation Strategy . J&D Wlkie - Exploitation of weaving technologies - Training and dissemination activities • Oxley Threads - Exploitafion of thread technologies - Training and dissemination activities • Flomerics - Exploitation of modelling technologies - Training and disseminafion activities • Solent Composites - Dissemination and exploitafion ofthe technology in the end markets - Training and dissemination acfivities • AMEC - Dissemination and exploitation ofthe technology in the end markets - Training and disseminafion activifies • Pera - Research and activities relating to technology transfer to the wider business community - Development of wider business strategy - Transfer knowledge from RTD pre-former to SME participants Management of project resource & technical activities at WP & Task level, including workflow scheduling. Work Plan change control & communication between partners & the DTl. Hitek - Chairing management board and running of quarterly steering committee meefings during the 2-year project duration. J&D Wlkie - Attendance at quarterly steering committee meetings Oxley Threads - Attendance at quarterly steering committee meetings Flomerics - Attendance at quarterly steering committee meetings -etc. Solent Composites - Attendance at quarterly steering committee meetings AMEC - Attendance at quarterly steering committee meetings Pera - Attendance at quarterly steering committee meetings - Ensure fimely, correct delivery of all milestones & deliverables throughout the lifefime of the project. - Monitor & integrate effort between R&D pre-formers & industrial partners for effective use of available resources. - Prepare project reports, patent drafts & provide effective IP protection of project results. - Management of resource & technical activities at WP & Task level, including workflow scheduling. Work Plan change control & communicafion between partners & TSB.

Moves to reduce carbon emissions and improve efficiency has primed interest in new technologies for the generation of electrical power. Unlike conventional plant, new generating technologies are not naturally suited to direct connection to the fixed frequency grid supply. Furthermore, in the case of renewable generation, restrictions on geographical location pose problems for electrical connection. Power electronic conversion thus plays a significant role in efficiently capturing and distributing the generated energy. This proposal addresses one important aspect of this research area: the efficient, robust and low-cost capture and transmission of renewable energy (RE) from multiple renewable resources. The use of DC networks to aggregate and transmit power from has been identified as a solution to such problems; to date work in this area has be concentrated at concept study and simulation level. Our collaborative proposal seeks to develop a novel and innovative DC current link system. The research will investigate the academic research aspects of realising a DC current link technology for the capture of renewable energy and other forms of low-carbon-derived electrical energy. Traditional wind turbine interfacing to the AC grid has been based on AC concepts. Recently ABB have installed the first offshore interconnect based on dc transmission. The system uses their standard HVDC Light technology, which offers bidirectional power flow control. Embedded renewable generation whether wind or wave, onshore or offshore, generally does not require the bidirectional power flow capability of HVDC Light (and similar techniques) but does require efficient, low-cost multi-source control. Existing techniques, e.g.HVDC Light, are not suitable. The proposed system departs from existing DC transmission technology. The proposed system is based on the concept that paralleling energy sources should always be based on paralleling current sources - not voltage sources as currently exemplified by HVDC systems. In our proposed system the single-ended step-up converter, operated with an outer current control loop, is the basic building block. The topology is scaleable, reliable and low-cost compared with existing AC and DC converter technologies used in distribution. Connection of additional sources is simple and low-cost thus the system lends itself to community-based schemes. Additionally, the majority of lower power RE systems utilise permanent magnet generators therefore require only unidirectional power flow from the RE source to the grid. The unidirectional nature of the power flow results in significant simplification of the DC system that is not realised in AC systems and existing bidirectional DC technology. The technology that will be developed by this project is a key enabler for the integration of multi-source low-carbon energy. The academic research team will investigate detailed modelling, simulation, design and experimentation on a demonstrator DC link system. Two PhD themes have been identified. The first will have a PhD student investigating the conversion electronics required to buffer and transform generates electrical energy onto the novel network. The second PhD student will research and address the important issue of regulating the flow of power from the low carbon energy source to the centralised grid interfacing converter. A post-doctoral research fellow will provide overall project management, liaise with the industry partner during development of the six-turbine demonstrator site, and assess and evaluate the performance of the demonstrator. On completion of this project, there will be a six 15kW turbine array that demonstrates the novel conversion technologies and innovative control algorithms developed through this important research. The demonstrator will be an exemplar of the synthesis between internationally-leading academic research, industrial experience and exploitation, and entrepreneurial skill.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Among technically and economically viable renewable energy sources, wind power is that which exploitation has been growing fastest in the recent years. This research focuses on modern Horizontal Axis Wind Turbines (HAWT's), which typically feature two- or three-blade rotors. The span of HAWT blades can vary from a few meters to more than 100 meters, and their design is a complex multidisciplinary task which requires consideration of strong unsteady interactions of aerodynamic and structural forces. Some of the most dangerous sources of aerodynamic unsteadiness are a) yawed wind, due to temporary non-orthogonality of wind and rotor plane, and b) blade dynamic stall. These phenomena result in the blades experiencing time-varying aerodynamic forces, which can excite undesired structural vibrations. This occurrence, in turn, can dramatically reduce the fatigue life of the blades and their supporting structure, yielding premature mechanical failures. Events of this kind can compromise the technical and financial success of the installation, which heavily relies on fulfilling the expectations of minimal servicing on time-scales of the order of 10 to 30 years. These facts highlight the importance of the aeroelastic design process of HAWT blades. The unsteady aerodynamic loads required to determine the structural response must be understood and accurately quantified in the development phase of the turbine. Due to the sizes at stake, in most cases it is infeasible to perform aeroelastic testing, not only from an economic but also logistic viewpoint. Hence these aeroelastic issues can only be tackled by using accurate simulation tools.The general motivation of this project is two-fold: it aims both at enriching the knowledge of unsteady flows relevant to wind turbine aeroelasticity, and advancing the state-of-the-art of the computational technology to accomplish this task. These objectives are pursued by using a novel Computational Fluid Dynamics (CFD) approach to wind turbine unsteady aerodynamics. The unsteady periodic flow relevant to aeroelastic analyses is determined by solving the three-dimensional unsteady viscous flow equations with the nonlinear frequency-domain (NLFD) technology. The NLFD-CFD approach has been successfully applied to fixed-wing and turbomachinery aeroelasticity. This research will exploit this high-fidelity methodology to enhance the understanding of the severe unsteady aerodynamic forcing of HAWT blades, and substantially reduce computational costs with respect to conventional time-domain CFD analyses. This method is particularly well suited to investigate the unsteady aerodynamic blade loads associated with stall-induced vibrations and yawed wind. On the other hand, this technology will greatly help designers to develop new blades without relying on the database of existing airfoil data on which the majority of present analysis and design systems depend. One of the main results of this project will be to greatly reduce the dichotomy between the conflicting requirements of physical accuracy and computational affordability of the three-dimensional unsteady viscous flow models for wind turbine unsteady aerodynamics and aeroelasticity. The achievements of this research will benefit the British and European industry in that they will offer an effective tool to design more efficient and reliable blades. The NLFD-CFD technology will also provide deeper insight into unsteady aerodynamic phenomena which affect the fatigue life of wind turbines. In the next few years, the certification process of wind turbines will enforce stricter requirements on the industry. The developed technology will support the analyses required to meet enhanced certification standards. The Unsteady Aerodynamics Research Community as a whole will also benefit from this research, because its findings will enhance and consolidate the deployment of the NLFD technology in rotorcraft, turbomachinery, and aircraft aeroelasticity.

Reducing the materials costs and improving efficiencies for solar cells is an ongoing research area that has global interest. Currently, crystalline silicon cells account for 90% of the PV market. Whilst conversion efficiency levels are considered high, the production costs for crystalline silicon are significantly higher than for thin film materials. However, the current conversion efficiency for thin film PV is significantly less than for crystalline silicon hence reducing some of the cost advantage. There is considerable scope for thin film solar cell development, where improvements in cell efficiency can be made with improved materials and device structures. One improvement that will lead to better conversion efficiency is to increase the photon absorption into the cell, close to the junction. A promising candidate for application as an absorbing layer in a photovoltaic device is iron pyrite (FeS2). The high absorption coefficient of FeS2 is consistent with its high density of states in the conduction band. The relatively small band gap allows for visible and infrared wavelengths to be absorbed, and the combination of direct and indirect band gap transitions contribute to its high absorption coefficient. However, this has not yet been turned into an efficient PV device. Iron pyrite has the potential to become a very important material for very large scale manufacture of thin film PV modules where the elemental constituents are very abundant and combines with the much smaller amounts of absorber material needed (thickness of 100 nm or less) making this a very sustainable and low cost material.This feasibility proposal will investigate the promising MOCVD route to deposit very thin films of FeS2 and introduce these into a novel p-i-n structure, taking advantage of the recent success with the MOCVD CdTe PV devices on the PV Supergen project. This structure will take advantage of the super-absorption characteristics to sandwich a very thin film absorber between n-type CdS and p-type CdTe:As layers. The purpose will be to show that high efficiency PV devices can be made from FeS2 where the photo-generated carriers are collected by drift in the electric field rather than by diffusion, thus reducing carrier loss. As part of the feasibility it is intended to scope future developments by replacing the CdS and CdTe n-type and p-type layers with more sustainable materials.

Rising atmospheric carbon dioxide levels, and concerns over energy security, mean that there is increasing interest in developing renewable energy technologies. Solar technologies are deemed to be particularly attractive, since over 100 000 TW of solar energy falls on the Earth every year. The human population currently use 10 TW of energy per annum, and by 2050, it is predicted that our energy demand will double to 20 TW per annum. It is therefore theoretically feasible that solar technologies could provide a significant proportion of our future energy requirement. However, harvesting a large proportion of this solar energy, in a cheap, efficient manner, poses many difficult technical challenges. At present, silicon based solar PV cells are the method of choice, but these devices tend to be very expensive to manufacture, since they contain highly purified, semi-conductive materials. In this application we propose to harness the photochemical reactions associated with photosynthesis, a fundamental biological process, to convert sunlight into a usable form of energy by means of a biological photovoltaic panel. Using a multidisciplinary consortium of groups based in Plant Science, Biochemistry, Genetics, Engineering and Chemistry we intend to develop, test and optimise biological photovoltaics for the production of hydrogen and/or electricity. A large amount of work has already been carried out in the field of biological hydrogen production, but so far it has proved difficult to overcome the major technical hurdle that limits the commercialisation of this technology, namely that the oxygen produced during photosynthesis inhibits the production of hydrogen from the hydrogenase enzyme in vivo. Although there has been some interest in fabricating artificial devices with purified protein complexes to overcome this problem, the instability of these proteins has prevented economic exploitation. In this application, we propose to separate the processes of oxygen evolution and hydrogen production in a semi-biological photovoltaic device using intact photosynthetic cells, in which protein complexes are intrinsically more stable, and which furthermore have mechanisms for self-repair. The device will be composed of two chambers, or half-cells, with oxygen evolution confined to one chamber and hydrogen production to the other. In addition, the approach can be used to produce a DC electrical current, in a manner analogous to standard silicon based photovoltaic panels.

The depletion of oil reserves, spiralling fuel costs, concerns about the security of global energy supplies, and belated worldwide recognition of fossil-fuel induced climate change have sparked an urgent and unprecedented demand for sustainable energy sources. Amongst all of these sources solar photovoltaic (PV) energy stands out as the only one with sufficient theoretical capacity to meet global electricity needs, but high costs of silicon based PV prohibit widespread take-up. In this programme, we focus on the development of organic photovoltaics (OPV) as a low cost technology with the potential to displace conventional power sources. The proposed programme links Imperial College London with four leading Chinese institutions, building on ICL's strengths in the physics and application of molecular electronic materials and devices and on our partners' strengths in speciality materials development and scale-up. A collaborative programme between the UK and China in this area is particularly timely, given the pressing need for alternative power sources that are capable of meeting the rapid development rate and large energy demand of China. Our proposal focuses on solution-processable organic molecules and polymers which share many of the chemical, structural and rheological properties of the inks used in conventional printing and which are amenable to large-scale production through the existing printing and coating industries. Although the project is focused on fundamental research in enhancing the efficiency and lifetime of OPV devices, the technology developed in this project will be compatible with high throughput manufacturing processes for large-scale production. In addition, the programme stands to benefit from the capabilities in China for transferring technological developments into local production. Solution processable OPV devices are typically based on the combination of an electron donor material (usually a conjugated polymer) and an electron acceptor (typically a fullerene derivative) in a bulk heterojunction structure. Absorbed photons of light create excitons which dissociate at the donor/acceptor interface to yield separated charges. The composite film is sandwiched between two different electrodes which drive photocurrent generation through the asymmetry in their electron affinities. The power conversion efficiency of OPV devices currently stands at 5%, and increases in both efficiency and lifetime are required to stimulate commercialization. Device models indicate that power conversion efficiencies of 8 % or more are available with polymer materials possessing sufficiently high oxidation potential and electrode materials with higher work function than those currently available. In this proposal, new polymer and electrode materials will be developed which possess the required properties for higher efficiency, new material which offer higher device stability will be designed and evaluated, and processing techniques compatible with large scale, high volume production will be developed. The programme brings together the expertise of the ICL team in device design, fabrication, characterisation and processing with the expertise of four leading Chinese institutions in synthesis of specialized organic semiconductors and their application in light emitting devices. Application of materials and device designs to light emission will also be investigated where appropriate, in order to explore the potential for energy savings in the lighting market.