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This paper explores how the requirement for energy storage capacity will grow as the penetration of renewables increases. The UK's electric grid is used as a case study. The paper aims to provide insight on what is the most economical solution to decarbonize the electric supply. A two-dimensional study varying the penetrations of wind and solar PV is carried out to identify the most appropriate generation mix for the country. The study is based on 9 years of demand and generation data with a 1hr resolution. It discusses the risk of underestimating the storage capacity needed, by failing to capture the inter-annual variability of renewables and analyzes the economic trade-off between over-generation (curtailment) and storage capacity. It also aims to determine the percentage of over-generation that minimizes the total cost of electricity. Results suggest that the UK could need a storage capacity of approximately 43 TWh to decarbonize its electricity supply. This figure considers a generation mix of 84% wind +16% solar PV, a roundtrip storage efficiency of 70%, and 15% of curtailment. Based on current costs of bulk energy storage technologies, this storage capacity translates into an investment of ∼£165.3 billion or approximately 7% of the country's GDP. • The UK will need 43 TWh of storage for a 100% renewable penetration with 15% curtailment. • If no overgeneration is allowed; storage increases to reduces to 116.5 TWh. • The generation mix has a very strong impact on the storage capacity required. • The optimum mix for the UK is a wind penetration of 84% and a solar PV penetration of 16%. • Considering current costs, a 100% renewable supply would have a LCOE of 80.2 £/MWh. [ABSTRACT FROM AUTHOR]

Various studies have assessed the energy performance alterations affected by the novel technology of Building-Integrated Photovoltaic in Double-Skin Facades (BIPV-DSF), while lighting performance tied to the BIPV-DSF has not received much attention. This paper provides numerical modelling to assess the effect of BIPV-DSF on both indoor visual condition and energy consumption for an office module under a typical climate in the United Kingdom. The proposed study was focused on the comparisons between a reference case (a DSF office module with both layers using clear double glazing) and a design case of the same office module with BIPV-DSF using semi-transparent Amorphous Silicon PV glazing. Results show a significant drop in maximum daylight illuminance of 73% by configuring the BIPV-DSF with reference to the regular DSF. It was also reported the resultant average and minimum daylight factors (0.65% and 0.00%) were not able to meet indoor visual comfort requirements for office environments. Furthermore, it was found that the use of BIPV-DSF resulted in a net increase of 8% in building energy consumption over the reference DSF. Therefore, it is concluded that in the present context the BIPV-DSF is not viable for a commercial installation under the UK's climate conditions. [ABSTRACT FROM AUTHOR]

This paper explores the effect of having a nuclear baseload in a 100% carbon-free electricity system The study analyses numerous scenarios based on different penetrations of conventional nuclear, wind and solar PV power, different levels of overgeneration and different combinations between medium and long duration energy stores (hydrogen and compressed air, respectively) to determine the configuration that achieves the lowest total cost of electricity (TCoE). At their current cost, new baseload nuclear power plants are too expensive. Results indicate the TCoE is minimised when demand is supplied entirely by renewables with no contribution from conventional nuclear. However, small modular reactors may achieve costs of ∼£60/MWh (1.5× current wind cost) in the future. With such costs, supplying ∼80% of the country's electricity demand with nuclear power could minimise the TCoE. In this scenario, wind provides the remaining 20% plus a small percentage of overgeneration (∼2.5%). Hydrogen in underground caverns provides ∼30.5 TWh (81 days) of long-duration energy storage while CAES systems provide 2.8 TWh (∼8 days) of medium-duration storage. This configuration achieves costs of ∼65.8 £/MWh. Batteries (required for short duration imbalances) are not included in the figure. The TCoE achieved will be higher once short duration storage is accounted for. [ABSTRACT FROM AUTHOR]

A primary drawback of solar thermal technologies, especially in a domestic setting, is that collection of thermal energy occurs when solar irradiance is abundant and there is generally little requirement for heating. Thermochemical Energy Storage (TCES) offers a means of storing thermal energy interseasonally with little heat loss. A combination of a Solar Thermal Collector (STC) and TCES system will allow a variety of different heating applications, such as domestic space and hot water heating as well as low temperature industrial process heat applications to be met in a low carbon way. This paper describes and assesses the feasibility of two novel technologies currently under development at Loughborough University; i) an evacuated flat plate STC and ii) composite TCES materials, coupled together into a system designed to store and supply thermal energy on demand throughout the year. Experimental results of composite TCES materials along with predicted performance of STC's are used within a developed model to assess key metrics of conceptual TCES + STC systems feasibility, including; charging time, payback time, cost/kWh, energy savings and CO 2 savings. This paper demonstrates the economic, energy and carbon savings potential of conceptual TCES + STC systems suitable for domestic use. • Economic feasibility of novel TCES + STC conceptual systems presented. • Conceptual systems using a Vacuum Flat Plate Collector are the most economical. • 30% of the domestic space heating demand can be supplied using these systems. • Significant CO 2 reductions possible if systems installed in UK households. • Systems predicted to result in financial savings to the homeowner. [ABSTRACT FROM AUTHOR]

For the physical model testing of wave energy converters (WECs) in the wave basin, it is necessary to test the models in a small number of sea states. Previously, the H – T binning method was widely used to determine the sea states that are representative of an ocean area. However, it omitted much useful information such as the wave directionality. In this paper, a novel method, the K -means clustering technique is used in combination with High Frequency (HF) radar measured data from Wave Hub, UK. The results show that K -means clustering method better preserves the characteristics of the ocean area than the binning method. Furthermore, the impact of different regrouping methods on assessing the annual energy output of the model is investigated, by applying the K -means clustering method to a 1:25 two-body hinged raft WEC. It is found that although non-linear performance can be clearly observed in the model both physically and numerically. Due to the fact that most sea states from Wave Hub are out of the non-linearity range of the model, the non-linear effect on the overall performance of the WEC model in this ocean area is limited. It allows the annual energy output to be accurately predicted by using only a small number of representative sea states (defined as K) ≤15, based on K -means clustering method. • K -means method selected representative sea states tested on a physical WEC model. • K -means method is effective in selecting the sea states for WEC model testing. • Representative sea states can obtain accurate annual energy output estimation. • Non-linearity of WEC tested had limited influence on annual energy output estimation. [ABSTRACT FROM AUTHOR]

Low carbon technologies along with smart control have a role in residential demand side response (DSR) to shift the timing of household energy consumption away from peak times and align it with generation of renewable electricity. This paper empirically evaluates the impact of DSR trials on grid electricity import and resident experience regarding disruption to daily routines, thermal comfort and noise disturbance in 17 thermally efficient social housing dwellings (Barnsley, England). Four types of DSR trials were run through 22 interventions performed in March to April 2021. Each dwelling was equipped with a 5 kWh electro-chemical battery and air source heat pump, and all but one dwelling had solar photovoltaic (PV) panels (1.3–3.0 kWp). Interventions were applied against a flat (single) rate tariff as well as dynamic time-of-use tariffs. On average, secure turn-down interventions between 5 and 7 p.m. resulted in a reduction in grid electricity import of 1.2 kWh per household and a reduction in controllable load (heat pump plus battery energy) of 3.7 kWh per household. The batteries enabled 2.5 kWh per household of electricity to be exported to the grid for these interventions. On average, turn-up interventions between 1 and 3 p.m. resulted in an increase of 2.3 kWh per household in grid electricity import. Individual dwellings showed different levels of demand response depending on the levels and patterns of household electricity consumption. The resident experience was evaluated by means of a series of telephone surveys. Householders were generally accepting of the trials in terms of changes in indoor temperature, hot water availability, noise disturbance and disruption to household routines. However, some general concerns were raised about the energy systems relating to indoor temperature, hot water temperature and energy costs. The general acceptability of automated DSR, conditional on thermal comfort limits and manual override, is promising for the wider application of residential DSR driven by price signals, although ongoing household engagement in DSR schemes will require a continued focus on the householder experience with training and support in using new technologies. A routine period of inspection should be employed to identify any issues with energy system issues ahead of DSR initiation. • Empirical evaluation of residential demand response trials. • Homes equipped with heat pumps, solar photovoltaic panels and batteries. • General householder acceptance of demand response under automated smart control. • System issues can be a potential barrier to residential demand response. • Engagement requires continued focus on householder experience, training and support. [ABSTRACT FROM AUTHOR]

5th generation district heating and cooling networks operating at near ground temperature offer a low-cost, zero-carbon energy solution. Detailed understanding and accurate estimation of ground behaviour for its heat storage and recharge potential are of paramount importance for the success of such networks. In this paper, an advanced modelling tool, based on a coupled Thermal-Hydraulic (TH) modelling framework, is presented to calculate and predict temperature and soil-moisture behaviour of a shallow ground under complex atmospheric, temperature and hydraulic boundary conditions. Atmospheric data e.g., solar radiation, rainfall, humidity, air temperature, wind velocity is considered together with subsurface soil data to investigate thermal and hydraulic responses of the ground, and its individual soil layers. Furthermore, a transient method for estimating shallow ground source heat (SGSH) resources is proposed based on the simulated temperature and saturation distributions of the ground. The model is applied to predict the long-term ground temperature and saturation level of a test site located in Warwickshire County, UK. The total heat content per unit area and the annual/seasonal/monthly net heat content per unit area of the site are predicted for a five-year period. The total heat content of the sandy clay layer varied between 2.32 and 11.6 MJ/m2, silty clay from 34.0 to 50.5 MJ/m2, and mudstone from 50.7 to 55.0 MJ/m2. A parametric sensitivity study is also conducted to investigate the effects of soil types and hydraulic drainage conditions on the ground heat supply potential, and it revealed that the spatial and temporal distributions of ground heat is significantly affected by the underlying soils. This study highlights the influences of atmospheric conditions and coupled ground processes, and the parameters that should be considered for designing a 5th generation low-temperature heat network. [Display omitted] [ABSTRACT FROM AUTHOR]

The objective of this paper is to develop an optimal scheduling scheme for an Energy Storage System (ESS), in a grid-connected microgrid, which is used for two main energy services, namely Operating Cost Minimization Service (OCMS) and Contracted Service (CS). OCMS refers to minimizing the overall operating cost of the microgrid. CS is a specified balancing service for the grid operator in UK to manage the actual demand when the demand is greater than forecast or generation availability. In this service, a constant contracted level of power is delivered by the ESS on instruction from the grid. A linear programming (LP) based optimization method is proposed to effectively combine these two services. Different simulation studies are conducted to test the effectiveness of the proposed method under variations in the renewable energy sources such as photovoltaic (PV) and wind in given microgrid. The proposed method is compared with a conventionally used Fuzzy Logic Control (FLC) based optimization method and is also experimentally validated. Simulation and experimental studies show that LP based optimization method can achieve a lower operating cost (up to 20%) in the microgrid and thus maximize the economic benefits of using an ESS by effectively managing different energy services. [ABSTRACT FROM AUTHOR]

Delivering low-carbon heat will require the substitution of natural gas with low-carbon alternatives such as electricity and hydrogen. The objective of this paper is to develop a method to soft-link two advanced, investment-optimising energy system models, RTN (Resource-Technology Network) and WeSIM (Whole-electricity System Investment Model), in order to assess cost-efficient heat decarbonisation pathways for the UK while utilising the respective strengths of the two models. The linking procedure included passing on hourly electricity prices from WeSIM as input to RTN, and returning capacities and locations of hydrogen generation and shares of electricity and hydrogen in heat supply from RTN to WeSIM. The outputs demonstrate that soft-linking can improve the quality of the solution, while providing useful insights into the cost-efficient pathways for zero-carbon heating. Quantitative results point to the cost-effectiveness of using a mix of electricity and hydrogen technologies for delivering zero-carbon heat, also demonstrating a high level of interaction between electricity and hydrogen infrastructure in a zero-carbon system. Hydrogen from gas reforming with carbon capture and storage can play a significant role in the medium term, while remaining a cost-efficient option for supplying peak heat demand in the longer term, with the bulk of heat demand being supplied by electric heat pumps. [Display omitted] • A multi-model approach is proposed to link two established energy system models. • Iterating between the two models focused on low-carbon heat and electricity sectors. • Various technologies are considered for electricity and heat decarbonisation. • Contributions of hydrogen and electricity to heat supply are assessed until 2050. • Evolution of the cost-effective portfolio of hydrogen sources is characterised. [ABSTRACT FROM AUTHOR]

This paper proposes a comprehensive analysis method for levelized costs of energy (LCOE) in tidal current power generation farms (TCPGFs). The detailed investment and operation costs in the life cycles of TCPGF projects are all quantified and incorporated in the calculation of LCOE, including the emission reduction benefits brought by TCPGFs. An annual electricity production (AEP) evaluation technique is proposed, in which the impacts of wake effects, TCPGF reliability and tidal current velocity (TCV) characteristics in the planning sea area are considered. A detailed capital expenditures (CAPEX) model is developed to incorporate all related costs at different stages of TCPGF project. An evaluation model considering the variations of annual operation expenditures (OPEX) is presented. The accuracy of the proposed method is verified using the measured data, which are collected from MeyGen Phase 1A project in UK and two sites located in UK and America. It can be seen from Figs. 2–3 that the repair and maintenance costs change synchronously with failure rate. This change shows a trend of first decreasing, then smoothing, and finally rising. Repair and maintenance costs account for more than 50% of OPEX. Therefore, the change trend of OPEX is similar to that of repair and maintenance costs. • A comprehensive model of levelized cost of energy is proposed. • The variations of annual operational expenditures are considered. • Reliability of tidal current power generation farms is analyzed. • The emission reduction benefits are quantified. [ABSTRACT FROM AUTHOR]

The inherent uncertainties associated with offshore wind are substantial, as are the investments. Therefore, investors are keen to identify and evaluate the risks. This paper presents a model to economically evaluate projects from an offshore transmission owner's perspective by considering the revenue streams, capital costs, and operational expenditure. To allow a more realistic economic evaluation, data, regulatory information, and expert knowledge are collected, curated and, where necessary, combined with statistical techniques. A generic 1.2 GW project is used as a case study. This research contributes to a deeper understanding of the severe uncertainties involved in offshore transmission planning and their impact on a project's expected profit. Understanding their impact, through a sensitivity analysis where individually one factor is varied within an interval, supports informed decision making with limited information. Uncertainty in interest rates, planned operational expenditure and, particularly, cable failure rates were found to be critical to an investor's return. For the case study considered, comparing cable failure rates based on operational experience to inputs based on literature, resulted in a 64.2% lower net present value. In conclusion, further research into cable failures, and addressing the uncertainty in inputs used for economic evaluations could be beneficial to the industry. • Economic model formulation from a UK offshore transmission owner's perspective. • Proposes model to support decision making of future offshore transmission systems. • Discusses input uncertainties regarding economic analysis of offshore transmission. • Impact of severe uncertainty on the investor's expected profit is investigated. • Severe uncertainty in cable failure rate significantly impacts the expected profit. [ABSTRACT FROM AUTHOR]

Domestic hot water (DHW) has a significant share in building's energy consumption. In order to reduce this consumption, various solutions have been proposed such as controlling the system in an efficient way, using renewable sources and using phase change materials (PCM) in the system to increase heat capacity. However, this study is not only offering heat capacity improvement of the DHW storage unit but also proposing that energy efficiency can be improved by controlling the heat releasing time of the PCM. In this study, supercooled PCM tubes are placed in a water tank and charged with a solar assisted heat pump unit, these supercooled PCM tubes can then be discharged anytime when the hot water is required. In this paper, a transient thermodynamic model is built for the whole system including solar collector, heat pump, water tank with PCM and DHW demand profile. System components are modelled and a 24 h of demand profile is used in simulation for a UK home for summer and spring weather conditions. The results show that the PCM tubes effectively compensate the morning peak hot water demand and reduce daily energy consumption around 12.1% and 13.5% by shifting heating provision from immersion heater to solar heat pump. • Solar assisted heat pump unit for DHW is modelled in transient state. • Supercooled PCM are placed inside the water tank. • Comparison of PCM enhanced and common tank performances in SAHP. • Supercooled PCMs compensate the morning peak DHW demand. • Supercooled PCMs reduce daily electricity consumption. [ABSTRACT FROM AUTHOR]

The contract for difference (CfDs) auctions are the cornerstone of the UK electricity sector's decarbonization policy and were introduced as part of the Electricity Market Reform in 2013. The CfD auctions appear to have been successful in achieving low bids for low-carbon technologies, especially offshore wind power. However, the design of the auction increases the probability of speculative bidding, while the one-shot nature of the auction prevents bidders from learning and from utilizing information efficiently. We show that implementing a stringent non-delivery penalty to induce truth telling can improve deployment rate without increasing support costs. Moreover, by holding regularly scheduled (annual, for example) auctions, information on technology cost decreases can be better incorporated into the bids, lowering investor uncertainty and thus having a positive effect on support costs. • This paper analyses auctions for allocation of offshore wind CfD contract in the UK. • We argue that CfD auction design increases possibility of speculative bidding. • We show a stringent penalty improves deployment rate without raising support costs. • Also, by holding regular auctions investors' uncertainty and costs can be lowered. [ABSTRACT FROM AUTHOR]

The work presented in the paper provides a detailed TRaNsient System Simulation (TRNSYS) model that simulates the performance of a solar photovoltaic – thermal (PV/T) collector and examines its potential contribution for household heating applications in the UK. Based on this, a system is modelled to simulate the hot water demand of a house through connecting the solar – thermal panel with a thermal storage tank, a pump and a controller. The results obtained from the simulation indicated by how much the solar panel is able to convert solar energy into electrical power and heat over different seasons of the year and provide the hot water needs of the household. The model was validated based on the experimental configurations of a hybrid heat pipe based solar PV/T module and through applying cooling cycles, the thermal and electrical outputs and efficiencies of the system were indicated. Through this, it is investigated that the temperature of the solar panel can be reduced on average by almost 25%, which subsequently, will result in an increase of the electrical power output by nearly 15%. The simulation results also assisted in investigating and analysing aspects such as the effectiveness and efficiency of the panel over different times of the year and helped to optimise the performance of the system. For instance, it is simulated that the system can provide hot water for the household throughout all seasons of the year and under different solar radiation conditions. However, it is discovered that in order for the system to meet the required output demand, input from an auxiliary power unit may always be necessary. • The performance of a solar PV/T collector is simulated through TRNSYS software. • The simulation models the hot water and electricity demand of a household in the UK. • The simulation is run to indicate the effect of cooling on the performance of the panel. • The results indicate by how much solar energy is converted into electricity and heating. • The results assist in analysing the efficiency of the PV/T over the course of a year. [ABSTRACT FROM AUTHOR]

Abstract: The variability of renewable energy is widely recognised as a challenge for integrating high levels of renewable generation into electricity systems. However, to explore its implications effectively, variability itself should first be clearly understood. This is particularly true for national electricity systems with high planned penetrations of renewables and limited interconnection such as the UK. Variability cannot be considered as a distinct resource property with a single measurable parameter, but is a multi-faceted concept best described by a range of distinct characteristics. This paper identifies relevant characteristics of variability, and considers their implications for energy research. This is done through analysis of wind, solar and tidal current resources, with a primary focus on the Bristol Channel region in the UK. The relationship with electricity demand is considered, alongside the potential benefits of resource diversity. Analysis is presented in terms of persistence, distribution, frequency and correlation between supply and demand. Marked differences are seen between the behaviours of the individual resources, and these give rise to a range of different implications for system integration. Wind shows strong persistence and a useful seasonal pattern, but also a high spread in energy levels at time scales beyond one or two days. The solar resource is most closely correlated with electricity demand, but is undermined by night-time zero values and an even greater spread of monthly energy delivered than wind. In contrast, the tidal resource exhibits very low persistence, but also much greater consistency in energy values assessed across monthly time scales. Whilst this paper focuses primarily on the behaviour of resources, it is noted that discrete variability characteristics can be related to different system impacts. Persistence and predictability are relevant for system balancing, whereas statistical distribution is more relevant when exploring issues of asset utilisation and energy curtailment. Areas of further research are also identified, including the need to assess the value of predictability in relation to other characteristics. [Copyright &y& Elsevier]

Abstract Incorporating PCMs into traditional building envelops is an effective way to minimise indoor temperature fluctuations and maximise thermal comfort in summertime. PCMW is of particular interest due to its ease of installation. This paper presents a theoretical analysis in which both outdoor air temperature and solar radiation are considered to predict the optimal melting temperature of an internal PCMW for passive indoor temperature control. Key factors influencing the selection of optimal melting temperature are studied including outdoor temperature, solar radiation, window size, air change rate (ACH), and external wall and window U-values. A case study was carried out on a lightweight building using real weather data for the summer months in the UK. The simulation was developed in EnergyPlus with the potential to reduce energy use while maintain the desired internal temperatures determined. The optimal melting temperature was found to be 23.4 °C during summer in the UK from a theoretical analysis, which showed good agreement with the numerical simulations performed. In summer, the percentage energy savings can be as high as 40% compared with a similar building without PCMWs and the period which temperatures are maintained within the thermal comfort range can be improved by up to 7.2%. Highlights • A method for predicted optimal melting temperature of internal PCMW was presented. • Solar radiation has a large effect on the selection of optimal melting temperature. • The optimal melting temperature was between 23 and 24 °C in summer time in the UK. • The percentage of energy savings can be as high as 40%. [ABSTRACT FROM AUTHOR]

This paper presents monitoring results of two examples of building integrated PV system investigated at the School of the Built Environment, University of Nottingham in the UK. One of the systems is installed on an educational building, and consists of a thin film PV fac¸ade appropriate for commercial or office suites. The other system is installed on a detached house, and uses crystalline PV roof slates, appropriate for domestic buildings. As the two buildings are significantly different in size, construction and occupancy, the design and selection of the PV system for each was also different. The monitoring investigation has assisted identification of shortfalls in performance and possible explanations have been suggested. The results presented in this paper provide information on the design process, and highlight similarities and differences in the design, installation, performance and economics of the two systems. [Copyright &y& Elsevier]

This paper presents an exploratory analysis of microgeneration installer businesses in the UK during a period of intense change in policies supporting microgeneration from 2010 to 2012. The research examines the influence of installer businesses on rates of uptake and standards of installation, and the interplay between business practices and the policy environment. The research developed new detailed datasets through a nationwide survey, to which 388 installers responded, and follow-up interviews with 22 installers. Focusing on solar photovoltaics and air source heat pumps installed in households, the results show the fundamental dependence of installer businesses on government financial incentives and on the quality assurance scheme in operation. Market confidence was compromised by the sharp reduction in the Feed-In Tariff (FIT) for residential solar PV in 2012 and long delays to the equivalent Renewable Heat Incentive for residential installations. Nevertheless, more modest FIT levels have reduced the risk of sub-optimal installations and inappropriate specification of microgeneration systems. The findings underline the need for consistent policy to allow installer businesses and their supply chains to develop and mature, and thus facilitate commercial deployment of microgeneration of high quality, raise its competiveness with incumbent forms of energy supply and contribute to decarbonisation goals. [ABSTRACT FROM AUTHOR]

In recent years there has been a significant change in the distribution of wind farms in Great Britain, with a trend towards very large offshore farms clustered together in zones. However, there are concerns these clusters could produce large ramping events on time scales of less than 6 h as local meteorological phenomena simultaneously impact the production of several farms. This paper presents generation data from the wind farms in the Thames Estuary (the largest cluster in the world) for 2014 and quantifies the high frequency power ramps. Based on a case study of a ramping event which occurred on 3rd November 2014, we show that due to the large capacity of the cluster, a localised ramp can have a significant impact on the cost of balancing the power system on a national level if it is not captured by the forecast of the system operator. The planned construction of larger offshore wind zones will exacerbate this problem. Consequently, there is a need for accurate regional wind power forecasts to minimise the costs of managing the system. This study shows that state-of-the-art high resolution forecast models have capacity to provide valuable information to mitigate this impact. [ABSTRACT FROM AUTHOR]

The integration of large capacities of wind and solar generation into the France and Great Britain (GB) power systems is expected to pose significant operational challenges. Electricity interconnectors can play a role in facilitating the integration of renewable generation in neighbouring countries by allowing power to flow freely between power systems and therefore smooth the net electricity demand. In this paper, role of the electricity interconnectors in efficient balancing of supply and demand in the France and GB power systems was evaluated in terms of overall reduction in the operational costs and curtailment of renewable generation, and also its impact on operation of gas-fired plants. The value of the France-GB interconnectors was studied for two generation mix scenarios in 2030 using PLEXOS. The outputs of the modelling showed the interconnectors will result in larger amount of wind and solar to be absorbed by both power systems which consequently will reduce overall operational costs and CO 2 emissions. In addition, the interconnectors will reduce burden on gas-fired plants compensating for variation in wind and solar generation. This can have a significant value in operation and required investment of gas networks in both countries. [ABSTRACT FROM AUTHOR]

This paper reports the methodology established in the application of a numerical wave model for hindcasting of wave conditions around the United Kingdom, in particular for Scottish waters, for the purpose of wave energy resource assessment at potential device development sites. The phase averaged MIKE 21 Spectral wave model has been adopted for this study and applied to the North Atlantic region bounded by latitudes 10° N–70° N and longitudes 10° E−75° W. Spatial and temporal wind speeds extracted from the European Centre for Medium Range Weather Forecast (ECMWF) have been utilised to drive the wave model. A rigorous calibration and validation of the model has been carried out by comparing model results with buoy measurements for different time periods and locations around Scotland. Significant wave height, peak wave period and peak wave direction obtained from the model correlated very well with measurements. Spatially varying statistical mean and maximum values of the significant wave height and wave power obtained based on a one-year wave hindcasting are in good agreement with the UK Marine Atlas values. The wave model can be used with high level of confidence for wave hindcasting and even forecasting of various wave parameters and wave power at any desired point locations or for regions. The wave model could also be employed for generating boundary conditions to small scale regional wave and tidal flow models. [ABSTRACT FROM AUTHOR]

Solar energy use in the UK is increasing dramatically, providing both heat energy and generation of electricity. This trend is expected to continue due to solar technologies becoming cheaper and more readily available along with low carbon government legislation such as the Renewable Heat Incentive (RHI) and Feed in Tariffs (FiTs) supporting solar energy deployment. However, the effects of climate change on the solar resource remain largely unstudied. Climate change affects cloud cover characteristics and consequently directly affects the performance of solar energy technologies. This paper investigates the UK solar irradiation resource for both the present and future climates. The present solar irradiation level was assessed through the conversion of 30 years of observed historical monthly average sunshine duration data. The method and results are validated by comparing the converted solar irradiation levels to actual solar irradiance measurements at weather stations with significant historical records of solar irradiance data. The impact of climate change is investigated across different regions of the UK by using the UKCP09 probabilistic climate change projections. We find that the current average UK annual solar resource is 101.2 Wm −2 , ranging from 128.4 Wm −2 in the south of England to 71.8 Wm −2 in the northwest of Scotland. It seems likely that climate change will increase the average resource in the south of the UK, while marginally decreasing it in the Northwest. The overall effect is a mean increase of the UK solar resource, however it will have greater seasonal variability and discrepancies between geographical regions will be reinforced. [ABSTRACT FROM AUTHOR]

Abstract: The study investigates the impact that construction of a Severn Barrage in the Severn Estuary, on the west coast of the UK, might have on local wave conditions. Implementation of a barrage will impact on tidal currents and water elevations in the wider region. There is strong tidal modulation of wave conditions under the natural regime and therefore barrage-induced changes to tidal conditions could affect wave modulation in the region. This paper uses Swan, an open source 3rd generation spectral wave model, to investigate the possible impacts of construction of a barrage on tidal modulation of the wave conditions. It is found that current variations, rather than water level variations, are the dominant factor in tidal modulation of wave conditions. Barrage implementation does not substantially change the modulation of the wave period or direction. However, barrage implementation does affect the tidal modulation of wave heights in the area of interest. The tidal modulation of the wave heights is generally reduced compared to the natural case; the peaks in the wave heights on an incoming tide are slightly lowered and there is lesser attenuation in wave heights on the outgoing tide. This modulation leads to net changes in the wave heights over one tidal cycle. For all of the tested wave conditions, this net change is small for the majority of the tested domain, namely to within ±5% of the no barrage case. There are some areas of greater change, most notably larger net increases in the wave heights near the North Somerset coast where the post-construction net wave height increase over a tidal cycle approach 20% of the pre-construction conditions. These changes do not impact coastal flooding because the wave height increase is not co-incident with high tide. Importantly, the maximum wave height is not increased and thus the likelihood of extreme events is not increased. The area of greatest reduction is between Swansea and Porthcawl. Changes over a neap tidal cycle show similar patterns of net change, but the modulation over the tidal cycle is different; primarily the magnitude of modulation is half that for the spring tide case and the shape is altered in some locations. [Copyright &y& Elsevier]

Abstract: This paper considers life cycle environmental sustainability of solar water heating systems in regions with low solar irradiation, such as the UK. The results suggest that flat plate collectors have slightly lower environmental impacts than evacuated tube designs. Reducing the current energy losses of 65%–45% would reduce the impacts by around 35%. Compared to a gas boiler, solar thermal systems are a better option for only five out of 11 environmental impacts considered, with global warming and depletion of fossil resources being lower by 88% and 83%, respectively. Other impacts such as human and eco-toxicity are up to 85% higher. The solar systems score better relative to electrical water heating for eight out of 11 impacts. They are also environmentally more sustainable than heat pumps for seven categories. However, their potential is hampered because they need a back-up heating system, typically gas boiler. For this reason as well as due to a lack of suitable locations and poor efficiency, the potential of solar thermal systems to contribute to a more sustainable domestic energy supply in the UK is limited. [Copyright &y& Elsevier]

Abstract: An analytical methodology for predicting above-roof mean wind speeds in urban areas is first used to map wind speeds over four different UK cities. The methodology utilises detailed geometric data describing buildings and vegetation to calculate the aerodynamic characteristics of the urban surfaces, and accounts for the influence of building height heterogeneity and wind direction upon wind profiles. The initial objective of the work is to determine the accuracy of the methodology when using detailed geometric data describing building roof shapes in addition to their heights, to estimate surface aerodynamic parameters. By integrating detailed LiDAR (light detection and ranging) data into the methodology and comparing the predictions with measured data, predictive accuracy is found to improve significantly with respect to previous results obtained using less detailed geometric datasets which describe each building with a single height. Subsequently, a preliminary evaluation of the cumulative, city-scale potential for generating wind energy is made, using the UK City of Leeds as a case study. The results suggest that from the point of view of wind resource, 2000 to 9500 viable building-mounted wind turbine locations may exist in Leeds, highlighting the potential for this technology to be far more widely deployed than has presently been achieved. However, the calculations are shown to be highly sensitive to the viable wind speed selected, which in turn depends on financial support and technological progress. An investigation is then made into where, in general, viable roof-top turbine locations may be found. The results suggest that there are viable sites distributed throughout the city, including within the complex city centre, where at the most suitable locations above-roof wind speeds may be comparable to those observed at well exposed rural sites. However, in residential areas, consisting of groups of buildings of similar heights, it is likely that the majority of properties will be unsuitable turbine locations. The wind maps and methodology described in this paper may be utilised by turbine suppliers and customers for assessing the viability of potential sites, as well as being instructive for policymakers developing subsidies for small-scale renewable energy projects. [Copyright &y& Elsevier]

Abstract: A case study of the development of an overall resource assessment for the Wave Hub site in the southwest UK is presented. Wave Hub is one of the earliest large-scale wave farms planned. Several resource assessment studies have been performed for the site, but the published results are high-level and predicted power availability varies significantly. This paper provides a detailed overview and re-analysis of the multiple datasets used in the original studies, which consisted of a combination of physical measurement and numerical modelling. The quality of the datasets is assessed, and reasons for the discrepancies between predicted resource levels investigated. Results from a SWAN model for the region illustrate significant levels of spatial variability in the resource due to the complexity of the local bathymetry, and examination of long-term global model datasets shows notable inter-annual variability. It is thus concluded that a resource assessment methodology utilising datasets from multiple locations and of short duration significantly reduces the accuracy of the predicted levels of resource. From these results, key learnings for future developments are discussed. [Copyright &y& Elsevier]

Abstract: Decentralised energy sources, such as small-scale-wind energy, have a number of well-known advantages. However, within urban areas, the potential for energy generation from the wind is not currently fully utilised. One of the most significant reasons for this is that the complexity of air flows within the urban boundary layer makes accurate predictions of the wind resource difficult to achieve. Without sufficiently accurate methods of predicting this resource, there is a danger that wind turbines will either be installed at unsuitable locations or that many viable sites will be overlooked. In this paper, we compare the accuracy of three different analytical methodologies for predicting above-roof mean wind speeds across a number of UK cities. The first is based upon a methodology developed by the UK Meteorological Office. We then implement two more complex methods which utilise maps of surface aerodynamic parameters derived from detailed building data. The predictions are compared with measured mean wind speeds from a wide variety of UK urban locations. The results show that the methodologies are generally more accurate when more complexity is used in the approach, particularly for the sites which are well exposed to the wind. The best agreement with measured data is achieved when the influence of wind direction is thoroughly considered and aerodynamic parameters are derived from detailed building data. However, some uncertainties in the building data add to the errors inherent within the methodologies. Consequently, it is suggested that a detailed description of both the shapes and heights of the local building roofs is required to maximise the accuracy of wind speed predictions. [Copyright &y& Elsevier]

Abstract: Tidal energy has the potential to play a key role in meeting renewable energy targets set out by the United Kingdom (UK) government and devolved administrations. Attention has been drawn to this resource as a number of locations with high tidal current velocity have recently been leased by the Crown Estate for commercial development. Although tides are periodic and predictable, there are times when the current velocity is too low for any power generation. However, it has been proposed that a portfolio of diverse sites located around the UK will deliver a firm aggregate output due to the relative phasing of the tidal signal around the coast. This paper analyses whether firm tidal power is feasible with ‘first generation’ tidal current generators suitable for relatively shallow water, high velocity sites. This is achieved through development of realistic scenarios of tidal current energy industry development. These scenarios incorporate constraints relating to assessment of the economically harvestable resource, tidal technology potential and the practical limits to energy extraction dictated by environmental response and spatial availability of resource. The final scenario is capable of generating 17 TWh/year with an effective installed capacity of 7.8 GW, at an average capacity factor of 29.9% from 7 major locations. However, it is concluded that there is insufficient diversity between sites suitable for first generation tidal current energy schemes for a portfolio approach to deliver firm power generation. [Copyright &y& Elsevier]

Abstract: This paper explores the photovoltaic (PV) industry in the United Kingdom (UK) as experienced by those who are working with it directly and with consideration of current standards, module efficiencies and future environmental trends. The government''s consultation on the comprehensive review for solar PV tariffs, proposes a reduction of the generation tariff for PV installations in the UK of more than 50%. The introduction of the Feed-In Tariffs scheme (FITs) has rapidly increased deployment of PV technologies at small scale since its introduction in April 2010. The central principle of FIT policies is to offer guaranteed prices for fixed periods to enable greater number of investors. A financial analysis was performed on two real-life installations in Cornwall, UK to determine the impact of proposed cuts to the FIT will make to a typical domestic PV system under 4 kW. The results show that a healthy Return on Investment (ROI) can still be made but that future installations should focus on off-setting electricity required from the national grid as a long term push for true sustainability rather than subsidised schemes. The profitability of future installations will have to be featured within in-service and end-of-service considerations such as the feed-in tariff, module efficiencies and the implications of costs associated with end-of-life disposal. [Copyright &y& Elsevier]

Abstract: Airflow through urban environments is one of the most important factors affecting human health, outdoor and indoor thermal comfort, air quality and the energy performance of buildings. This paper presents a study on the effects of wind induced airflows through urban built form using statistical analysis. The data employed in the analysis are from the year-long simultaneous field measurements conducted at the University of Reading campus in the United Kingdom. In this study, the association between typical architectural forms and the wind environment are investigated; such forms include: a street canyon, a semi-closure, a courtyard form and a relatively open space in a low-rise building complex. Measured data captures wind speed and wind direction at six representative locations and statistical analysis identifies key factors describing the effects of built form on the resulting airflows. Factor analysis of the measured data identified meteorological and architectural layout factors as key factors. The derivation of these factors and their variation with the studied built forms are presented in detail. [Copyright &y& Elsevier]

Abstract: Wind power, especially offshore, is considered one of the most promising sources of ‘clean’ energy towards meeting the EU and UK targets for 2020 and 2050. Deployment of wind turbines in constantly increasing water depths has raised the issue of the appropriate selection of the most suitable support structures’ options. Based on experience and technology from the offshore oil and gas industry, several different configurations have been proposed for different operational conditions. This paper presents a methodology for the systematic assessment of the selection of the most preferable, among the different configurations, support structures for offshore wind turbines, taking into consideration several attributes through the widely used multi-criteria decision making method TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) for the benchmarking of those candidate options. An application comparing a monopile, a tripod and a jacket, for a reference 5.5 MW wind turbine and a reference depth of 40 m, considering multiple engineering, economical and environmental attributes, will illustrate the effectiveness of the proposed methodology. [Copyright &y& Elsevier]

Abstract: This paper reports on the current UK scenario of islanded operation of active distribution networks with renewable distributed generators (RDGs). Different surveys indicate that the present scenario does not economically justify islanding operation of active distribution networks with RDGs. Anti-islanding protection schemes currently enforce the renewable distributed generators (RDGs) to disconnect immediately and stop generation for grid faults through loss of grid (LOG) protection system. This greatly reduces the benefits of RDG deployment. With rising RDG penetration, much benefit would be lost if the RDGs are not allowed to island only due to conventional operational requirement of utilities. For preventing disconnection of RDGs during LOG, several islanding operation, control and protection schemes are being developed. Technical studies clearly indicate the need to review parts of the ESQCR (Electricity Safety, Quality and Continuity Regulations) for successful islanded operations. Commercial viability of islanding operation must be assessed in relation to enhancement of power quality, system reliability and supply of potential ancillary services through network support. Demonstration projects under Registered Power Zone and Technical Architecture Projects should be initiated to investigate the usefulness of DG islanding. However these efforts should be compounded with a realistic judgement of the associated technical and economic issues for the development of future power networks. [Copyright &y& Elsevier]

Abstract: The benefits of reducing the thermal effect of global warming and structural damage by severe storms have renewed interest and drives to heavyweight constructions. One type of heavyweight construction using earth-sheltered construction known as an ‘Earthship’ has been developed and pioneered by US architect Michael Reynolds and recently introduced to the UK. The ‘Earthship’ takes on the concept of an ‘independent vessel’, which operates on a self-sufficient basis and is constructed largely from recycled and reclaimed materials. Although there are up to 3000 globally, only two Earthships have been built in the UK – one in Brighton and one in Scotland. The publicity resulting from the planning approval granted in April 2007 for the construction of sixteen domestic Earthships at the seafront of Brighton have raised public awareness to this type of unconventional construction. A key feature of the Earthship design is the use of a thermal store, which acts as a seasonal heat buffer to absorb heat in the summer and to release heat in the winter, to regulate the room temperature. This paper reports on the initial findings of a long-term study on the thermal behaviour of the thermal store and its effect to the indoor environment. It introduces the design and construction principles of the Earthship and outlines the process and equipment used in the thermal monitoring of the building. Indicative results from the analyses of the data collected at the early stage are reported and discussed. Initial findings have demonstrated the effectiveness of the thermal charging and discharging of the earth-rammed thermal mass, which appeared to moderate the extreme external temperatures. [Copyright &y& Elsevier]

Abstract: This paper compares conditions and costs for RES-E grid connection in selected European countries. These are Germany, the Netherlands, the United Kingdom, Sweden, Austria, Lithuania and Slovenia. Country specific case studies are presented for wind onshore and offshore, biomass and photovoltaic power systems, as based on literature reviews and stakeholder interviews. It is shown that, especially for wind offshore, the allocation of grid connection costs can form a significant barrier for the installation of new RES-E generation if the developer has to bear all such costs. If energy policy makers want to reduce the barriers for new large-scale RES-E deployment, then it is concluded that the grid connection costs should be covered by the respective grid operator. These costs may then be recouped by increasing consumer tariffs for the use of the grid. [Copyright &y& Elsevier]