Energy group

The energy group staff are Andrew Knox, Calum Cossar, James Buckle and Andrea Montecucco. The associated PhD students include Liam MacIsaac, Graham Morton, Jeremiah Matthey, Craig Clanachan, Matthias Willig and Jonathan Siviter. Collaborations within the group include with Profs Cartmell, O'Reilly and Paul in the School of Engineering. One of the energy areas we focus on is microgeneration technologies. Microgeneration is a term often used in the context of electrical power generation and and with space and water heating. Typically these systems are aimed at the domestic and small commercial market, up to approx 50kW output. We have active research in the following areas:

• Application of thermoelectric devices

• Stirling engines

• Maximum power converters and Smart microgrids

• Optical fibre sensor for harsh environments

More details on the research activities of the enrgy group are also available in the following posters:

• poster 1: Stirling engines 
• poster 2: energy scavenging  
• poster 3: smart microgrids 
• poster 4: domestic microCHPs
• poster 5: micro energy harvesting 

Several members of the Energy group are also highly active in the University of Glasgow’s Formula Student team, UGRacing. Through 4th year team project supervision and during spare time, the team guide and help create the electronics to support the team vehicles, from design to fabrication and installation. Projects include engine management systems, tyre temperature measurement systems, electronic gear control, optical ground speed measurement and supporting engine tuning by creation of an engine dynamometer and software. All projects aim to use the minimum energy possible and in keeping with the trend in commercial vehicle manufacturers, the team aim to create a full-electric vehicle.

Application of thermoelectric devices

Project 1. Heat exchangers and heat pumps. Work conducted in partnership with Doosan Power Systems.

The Energy Act 2010 introduced CO2 Capture and Storage (CCS) incentives to support the construction of four commercial-scale CCS demonstration projects in UK. This legislative goal has spurred development of CCS and Doosan Power Systems has invested significantly in the development of Post Combustion CO2 Capture and Oxyfuel technologies to target this market.
New supercritical plants and CCS retrofits have been designed to improve thermal efficiency with the use of advanced high temperature materials, and sophisticated boiler technologies. However, there are issues with low grade temperature waste, and the high cooling duty of PCC and Oxyfuel plants. The plant cycle efficiency can be improved by implementing heat scavenging technology in each plant configuration where heat is rejected.
Heat exchangers are normally used around a plant to control the temperature of specific fluids and processes. Thermoelectric devices can be used in a heat exchanger to either aid cooling by pumping heat (Peltier effect) or, extract electrical energy using the temperature difference between the fluids (Seebeck effect).
The aim of this work is to study the effect of both a Peltier device and a Seebeck device (thermoelectric generator) in particular configurations, in order to maximise energy efficiency and ultimately improve the cycle efficiency of power plants with and without CCS technologies.

Project 2. Off-grid thermoelectric power generation from biomass energy sources

Thermoelectric generators (TEGs) are semiconductor devices which generate a voltage when the two junctions are maintained at different temperatures, exploiting the Seebeck effect. Our aim is to use TEGs in conjunction with traditional solid-fuel stoves to supply up to 100W of electrical power, thereby enabling the use of a fan or circulating pump to move hot air or water around the system without the need for a mains electricity source.
TEG efficiency is around 5%, but they can be successfully used as a sustainable source of energy in applications where waste heat is rejected from other necessary processes. Separate research work is addressing the efficiency of TEGs.
Our research is focused on 1)  understanding their physical and electrical behaviour, developing a Matlab and Simulink model, 2) utilising TEG modules available in the market to improve the efficiency of households and industry equipment, and 3) design a complete system composed by TEG modules, power converters with MPPT control to exploit waste heat to produce usable electrical power.
A related activity is the development of high efficiency DC-DC converters which will be used to stabilise the power developed by the TEG arrays. Most analog and digital electronic systems require a regulated DC power supply, which means that the voltage must be held constant within a specified tolerance level. This task is done by DC-DC power converters together with a feedback controller. Nowadays the control is usually designed with analogue electronics, but digital control is a valid alternative which provides some advantages like sequencing, monitoring, auto-tuning, communication, sleep-mode.
Our research is focused on designing fast and robust digital control for DC-DC converters, using microcontrollers. As their price is decreasing and their computational power increasing, they will increasingly be of importance in future power control. Present research is investigating problems related to  the error in the ADC conversion, the computational speed and the precision of the digital PWM.

Stirling engines

Project 1. High Power Stirling Engines and Heat Recovery

Stirling engines are a form of heat engine that uses a sealed quantity of gas to extract power from a difference in temperature across its extremities. This temperature difference can be created by any method, from solar to biomass fuels, purposefully created or recovered from another process that wastes heat. These have seen a recent increase in popularity in combined heat and power micro-generation systems due to their high thermal efficiency, low noise and low maintenance requirements. Work is on-going to develop a pressurised, high temperature difference, twin-alpha style Stirling engine designed to operate up to the 1kW output range. This engine is designed to function over a range of operating temperatures and pressures and is heated by a novel internal electric heating device, allowing precise and rapid power input control. It has been designed in a modular fashion to allow rapid component interchange to test material properties and examine differences in working fluid temperature and pressure. The concept of active Stirling control, modifying specific engine parameters in order to obtain an extended operating envelope and higher efficiency, as well as the possibilities of other forms of waste heat recovery such as thermoelectric generation are under investigation.

Project 2. Stirling engine dynamics and kinematics

Detailed investigations of the mechanical aspects of the Stirling engine are underway with a view to increasing power output and engine efficiency in order to boost the technology's viability as an energy generation unit for the modern market.  As part of the investigation a dynamic model of a Stirling engine is being developed, looking at ways to accurately simulate the theoretical aspects of the engine and correlate this with practical engine characteristics.   Another area of focus is in controlling the phase angle between the two pistons in the engine, allowing greater periods of heat transfer and larger power densities for any given engine.  Investigations of the dynamic effects of modifying the phase angle throughout the cycle and how this will impact on other engine characteristics such as component wear and external vibrations are also underway.  Additionally a physical engine is being built to allow comparison and this will provide a test bed for different configurations and mechanisms for controlling the pistons' phase angle.

Project 3. Electronic engine control

This project is investigating the viability of controlling a Stirling engine using electronic means, analogous to an Electronic Control Unit used in modern cars. A large range of different sensors and actuators are fitted to measure crank phase angles, temperatures and pressures, RPM, etc. Work is presently focussed on the control of the position of the displacer piston in the Stirling engine thereby regulating the gas flow and hence work extractedIn the near future a fully functioning Stirling engine which includes complete instrumentation and control through electronic means will be assembled. The aim is to show that additional control enables greater work output than is available using a fixed phase angle between the pistons.

Smart microgrids

Smart Grids are an emerging technology in which elements of the grid such as generation, monitoring and control are distributed throughout the network. This is in contrast to the hierarchical layout of these elements that is often seen in traditional power grids. Future developments that have been proposed for smart grid technology include the control of small-scale distributed generation and storage devices and the control of energy consumption through the use of smart appliances.

A software simulation package is being developed which will allow for the modelling of smart grids at the end user level. The package allows for the simulation of systems involving electrical, heating and communication elements. Within this package, complete energy consumption models of domestic or business premises including smart grid control elements can be created and analysed. One particular system which has been modelled in the package is a maximum power point tracker for photovoltaic panels. A comparison of maximum power point tracking algorithms was carried out and a new, more efficient algorithm was created.

Optical fibre sensors for harsh environments

Energy security is one of the key issues facing us today. In addition to developing sustainable energy generation technologies it is imperative that current energy sources such as those based on fossil and nuclear fuels are used with maximum efficiency and safety in order to minimise environmental impact. Key to efficient operation is the accurate monitoring of combustion parameters and in particular temperature. Current sensors can fail due to the harsh operating environment which leads to corrosion, fracture and erosion of sensor components over prolonged exposure. Single-crystals such as sapphire, yttria and zirconia are attractive materials on which to base sensors since they are extremely robust and can withstand the elevated temperatures, high pressures as well as the aggressive and corrosive chemicals typically found under combustion conditions in commercial plant. Similar conditions can be found in gas turbines (e.g. aircraft engines) where fuel efficiency, minimum sensor weight and electrical passivity are critical.

In nuclear power generation long term exposure to high levels of radiation can prove problematic for sensor systems. Sapphire is an extremely radiation hard material which can withstand long term exposure to extremely high levels of radiation with little effect on its optical or mechanical characteristics. Strain sensing is commonly used in structural monitoring and sapphire based strain sensors are being developed for long term monitoring of structural integrity. The figure in the left column shows a sapphire fibre with grating.