Challenges in the Development of Micro Gas Turbines for Concentrated Solar Power Systems

Parabolic solar dish systems have gained more interest recently as a reliable way for harnessing the solar power in form of electricity. Micro gas turbines can be usedas engines in such system to convert the heat available from the solar collector o electricity. In this paper the technical challenges related to using micro gas turbines for utilising concentrated solar power will be addressed based on the experience gained from the EU funded project OMSoP (Optimised Microturbine Solar Power system) which aims todevelop and demonstrate a micro gas turbine coupled to a parabolic dish for the power range of 5–10 kW. The technical challenges related to the turbomachinery design, rotordynamics and dynamic stability, control system, power electronics and thermal storage will be briefly reviewed. Techno economic considerations of the system will also be discussed

Development and Validation of a Thermo-Economic Model for Design Optimisation and Off-Design Performance Evaluation of a Pure Solar Microturbine

The aim of this paper is to present a thermo-economic model of a microturbine for solar dish applications, which demonstrates the applicability and accuracy of the model for off-design performance evaluation and techno-economic optimisation purposes. The model is built using an object-oriented programming approach. Each component is represented using a class made of functions that perform a one-dimensional physical design, off-design performance analysis and the component cost evaluation. Compressor, recuperator, receiver and turbine models are presented and validated against experimental data available in literature, and each demonstrated good accuracy for a wide range of operating conditions. A 7-kWe microturbine and solar irradiation data available for Rome between 2004 and 2005 were considered as a case study, and the thermo-economic analysis of the plant was performed to estimate the levelised cost of electricity based on the annual performance of the plant. The overall energy produced by the plant is 10,682 kWh, the capital cost has been estimated to be EUR 27,051 and, consequently, the specific cost of the plant, defined as the ratio between the cost of components and output power in design condition, has been estimated to be around EUR 3980/kWe. Results from the levelised cost of electricity (LCOE) analysis demonstrate a levelised cost of electricity of EUR 22.81/kWh considering a plant lifetime of 25 years. The results of the present case study have been compared with the results from IPSEpro 7 where the same component characteristic maps and operational strategy were considered. This comparison was aimed to verify the component matching procedure adopted for the present model. A plant sizing optimisation was then performed to determine the plant size which minimises the levelised cost of electricity. The design space of the optimisation variable is limited to the values 0.07–0.16 kg/s. Results of the optimisation demonstrate a minimum LCOE of 21.5 [EUR/kWh] for a design point mass flow rate of about 0.11 kg/s. This corresponds to an overall cost of the plant of around EUR 32,600, with a dish diameter of 9.4 m and an annual electricity production of 13,700 [kWh]

Reducing Levelised Cost of Energy and Environmental Impact of a Hybrid Microturbine-Based Concentrated Solar Power Plant

A multi-objective optimisation of a hybrid solar dish power plant aiming to minimise the levelised cost of energy while keeping emissions as low as possible is presented in this paper. The analysis was carried out for both regenerative Brayton-Joule regenerative cycle and inter-cooled and re-heated regenerative cycle using an analysis tool developed during this research and validated against available experimental data. The plant optimisation was performed using a fast and computationally efficient optimisation technique called “response surface optimisation”, which generates an approximated function (or response surface) that can be used to find a set of thermodynamic parameters that maximise the plant efficiency while minimising emissions. A Design of Experiment (DOE) Latin hypercube technique was used to generate the training database and a one-dimensional model were used to evaluate the output variables for each point of the database. The DOE was then coupled to a Second Order Polynomial regression technique to approximate the behaviour of the system in the design space. A genetic algorithm was then applied in order to find a high performance arrangement. Results show a good trade-off between emissions and levelised cost of energy for both plant layouts. The first arrangment shows a minimum levelised cost of energy in the range between 38.5 and 38.8 €cts/kWh with an electrical power production of about 8kW. The second showed a LCOE in the range between 50.5 and 51 €cts/kWh and a net electrical power output of 16 kW

Contribution of encouraging the future use of biomethane to resolving sustainability and energy security challenges: The case of the UK

The focus of this research is the potential of biomethane in Britain's gas grid. It examines its relative ability to address Britain's sustainability and energy security challenges from an economic perspective. Such research is important because UK is wedded to gas for heat production and power generation and is increasingly dependent on imported gas, in line with shrinking domestic production, and uncertain future trading relationships. Also, dependency on natural gas, threatens Britain achieving its legally-binding carbon budgets. The study included a thorough literature review, primary research to finally uncover the views of key UK market participants plus analytical modelling. The findings reveal that the market is cautiously optimistic, despite reservations regarding feedstock availability and the impending cessation of subsidy approvals. Investors are in greater need of long-term certainty, however, and the challenge of decarbonising heat and heavy-duty transport warrants this. Retail price premiums are polarised but, in line with wholesale costs, relatively high compared to electricity. The key recommendation is for the policymakers to follow precedents in renewable electricity and liquid biofuels, by mandating that energy suppliers, owners of heavy-duty road fleets and occupiers of new buildings purchase biomethane. In tandem, feedstock and grid-entry restrictions must be tackled creatively

Multi-Objective Optimisation of A Centrifugal Compressor for a Micro Gas Turbine Operated by Concentrated Solar Power

Solar powered micro-gas turbines (MGTs) are required to work over a wide range of operating conditions due to the fluctuations in the solar insulation. This means that the compressor has to perform efficiently over a wider range than in conventional MGTs. To be able to extend the efficient operating range of a compressor at the design stage, both impeller blades and diffuser passage need to be optimised. Vaneless diffusers could offer more flexibility to extend the operating range than typical diffuser vanes. This paper presents a methodology for the design and optimisation of a centrifugal compressor for a 6 kW micro-gas turbine intended for operation using a Concentrated Solar Power (CSP) system using a parabolic dish concentrator. Preliminary design parameters were obtained from the overall system specifications and detailed cycle analysis combined with practical constraints. The compressor’s geometry optimisation has been performed using a fast and computationally efficient method, which involves the Latin hypercube Design of Experiment (DoE) technique coupled with the response surface method (RSM) in order to build a regression model through CFD simulations. Three different RSM techniques were compared with the aim to choose the most suitable technique for this specific application and then a genetic algorithm was applied. The CFD analysis for the optimised compressor showed that the high efficiency operating range has increased compared to the baseline design. Cycle analysis for the plant has been performed in order to evaluate the effect of the new compressor design on the system performance. The simulations demonstrated that the operating range of the plant was increased by over 30%

A methodology for techno-economic and operation strategy optimisation of micro gas turbine-based solar powered dish-engine systems

This paper focuses on the optimisation of small-scale micro gas turbines totally powered by the concentrated solar power to generate electricity in the range of 5–30kWe. The objective of this paper is to investigate of the potential of such systems for solar power generation at reasonable costs. The computational model uses a component-based approach for thermodynamic performance simulation and features an integrated economic model which allows for the evaluation of economic performance indicators including levelised cost of electricity. The integrated model is coupled to a genetic algorithm optimisation framework to find system designs with optimal techno-economic performance. Two cases of fixed 5kWe rated power and 5-30kWe systems are studied. The performance simulation considers the operation strategy and the safe operation limits. A multi-objective optimisation is performed for each case to find trade-offs between the performance and cost of the system. The levelised cost of electricity and annual solar to electric efficiency are considered for comparison purposes. Results show that a levelised cost of electricity of about 170€/MWh can be achieved for a system installed in Italy. Lower cost of electricity as low as 85€/MWh could be achieved when considering economy of scale and locations with higher annual insolation.OMSoP project (https://etn.global/research-innovation/projects/omsop/) provided by the European Commission's FP7 programme, grant agreement No 30895

A System Dynamics Approach to Assess the Impact of Policy Interventions on the Market Penetration of Micro Gas Turbines

Paper No: GT2023-101952, V005T06A009.Decentralized power generating systems, such as micro-gas turbines (MGT) for micro combined heat and power (CHP), can contribute to achieving the global energy and emission targets thanks to features like low emissions, primary energy savings, and fuel flexibility. It can also help increase the share of renewables due to its ability to easily integrate with renewable energy systems. Micro gas turbines, despite being such a promising technology, have achieved very limited market success due to barriers like high investment costs and a lack of supporting policies. The large-scale market penetration of MGT requires clear and strong policy support to achieve widespread adoption. This paper establishes a quantitative model to assess the impact of the policy measures on the long-term market penetration of MGT for the domestic micro-CHP to establish a relationship between policy parameters, economic factors, technological advancements, and the market share of MGT. The work compares five different policy scenarios for the case study of the UK market. The results demonstrate that the usual economic forces are insufficient for MGT to achieve its long-term market growth. Several combinations of direct and indirect policies are to be implemented by the regulatory authorities to promote the commercial growth of the technology. Finally, some insight into policy and decision-making in the UK for micro-CHP is provided, indicating promising policies to pursue.European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No 861079. City, University of London

Numerical study of longitudinal vein effects on the aerodynamic characteristics of a corrugated bio-airfoil

The purpose of the present study is to investigate the influence of cross-sectional veins topology on the flow pattern and aerodynamic performance of a pitching corrugated bio-inspired airfoil. To demonstrate the vein effects, a cross-section of Ashena Cyanea wing is modelled with three configurations. The airflow passing bio-airfoil is subjected to three Reynolds numbers of 1000, 5000, and 14000 and selected reduced frequencies () and angular amplitude (). The results show that as the Reynolds number increases, the effects of veins structure become more significant. The lift coefficients of the three modelled bio-airfoils are almost identical over the range of selected Reynolds number. At the Reynolds numbers of 1000 and 5000, the thin bio-airfoil has a minimum drag coefficient, and the drag coefficients of thick and veined bio-airfoils are quite similar. The veins in the bio-airfoils increase the drag coefficient significantly for the Reynolds numbers of 14000 compared to the Reynolds number of 5000. Finally, the numerical simulations provide hysteresis of lift and drag coefficients subjected to an increment for Reynolds number, reduced frequency, and angular amplitude

Development of a Model for Performance Analysis of a Honeycomb Thermal Energy Storage for Solar Power Microturbine Applications

Solar power microturbines are required to produce steady power despite the fluctuating solar radiation, with concerns on the dispatchability of such plants where thermal energy storage may offer a solution to address the issue. This paper presents a mathematical model for performance prediction of a honeycomb sensible-heat thermal energy storage designed for application of concentrated solar power microturbine. The focus in the model is to consider the laminar developing boundary layers at the entry of the flow channels, which could have a profound effect on the heat-transfer coefficient due to large velocity and temperature gradients, an effect which has not been considered in the modelling of such storage systems. Analysing the thermal and hydrodynamic boundary layer development, the Nusselt number and the friction factor were evaluated using a validated conjugate heat-transfer method. The simulations results were used to develop accurate regression functions for Nusselt number and friction factor. These formulations have been adopted within a one-dimensional model to evaluate the performance of the storage under different operating conditions. The model was in good agreement with conjugate heat transfer results with maximum relative error below 2%. Two case studies are presented to demonstrate the applicability of the proposed methodology

A methodology for techno-economic and operation strategy optimisation of micro gas turbine-based solar powered dish-engine systems

This paper focuses on the optimisation of small-scale micro gas turbines totally powered by the concentrated solar power to generate electricity in the range of 5e30kWe. The objective of this paper is to investigate of the potential of such systems for solar power generation at reasonable costs. The computational model uses a component-based approach for thermodynamic performance simulation and features an integrated economic model which allows for the evaluation of economic performance indicators including levelised cost of electricity. The integrated model is coupled to a genetic algorithm optimisation framework to find system designs with optimal techno-economic performance. Two cases of fixed 5kWe rated power and 5-30kWe systems are studied. The performance simulation considers the operation strategy and the safe operation limits. A multi-objective optimisation is performed for each case to find trade-offs between the performance and cost of the system. The levelised cost of electricity and annual solar to electric efficiency are considered for comparison purposes. Results show that a levelised cost of electricity of about 170V/MWh can be achieved for a system installed in Italy. Lower cost of electricity as low as 85V/MWh could be achieved when considering economy of scale and locations with higher annual insolation