Energy Management Group
Department of Electrical & Electronic Engineering
Merchant Venturers Building
Woodland Road
Bristol BS8 1UB
United Kingdom
T +44 117 954 5499
F +44 117 954 5206
E energy-management
@bristol.ac.uk
Recent developments in functional materials, micro-engineering and nanoscience have provided us with the possibility of creating completely autonomous miniature sensors that are powered by energy taken from their immediate surroundings instead of requiring batteries or power leads. At the same time, small renewable energy generation is emerging as a viable method of powering off-grid communities, zero-carbon homes, and industry in areas with an unreliable electricity network. New generation concepts are being developed, such as wind turbines for turbulent conditions, or hydropower turbines for very low heads. The interconnection of dynamically changing power usage and these variable sources requires bidirectional energy flow, effective storage of intermittently supplied energy, and the integration and management of multiple and diverse energy sources.
The improvement of efficiency and power density of electric power conversion technology assumes an ever-increasing importance, in part due to the progressing electrification of systems. High efficiency power conversion is key to any electrical system that incorporates variable or bidirectional energy flow, effective storage of intermittently supplied energy, and the use of multiple and diverse energy sources.
Example projects in this area have included the control of off-grid renewable power systems with multiple wind and solar power sources, and small hydropower projects. Wind tunnel and hydro flume facilities are available in the Faculty of Engineering for this type of research.
An ongoing research project in this area has improved the understanding of electromagnetic interference (EMI) generation mechanisms in switch-mode power electronics, and of how to increase the energy efficiency without increasing electromagnetic interference. The project is now focused on developing improved methods of power device control that will allow these efficiency improvements. High-frequency measurement, simulation and control of device switching behaviour are the tools being used to achieve these aims.
Another ongoing area of research is the use of new materials in the power conversion components. Gallium Nitride (GaN) allows the active components of power converters to operate at much higher current densities, thus significantly improving energy efficiency and power density of switch-mode power electronic converters. Commercially available Gallium Nitride on Silicon field-effect transistors have been evaluated in the laboratory, and simulated using group computing facilities. Switching techniques for maximising the benefit that may be achieved from using these devices are being identified and developed. New semiconductor technologies such as Gallium Nitride potentially offer a step change in the performance of future energy management systems.
The Group is working on developing ultra energy-efficient electronic systems for emerging applications including mobile digital health, and autonomous wireless monitoring in environmental and industrial settings. An example project is the development of automated control of miniature energy harvesters in order to tune them to the frequency of ambient vibration, and the intelligent management of integrated electronic systems in order to reduce their power consumption. Related projects include ‘extreme sensing’, for example the measurement of unwanted vibrations on rotor blades, or the measurement of indicators of global warming under glaciers. By use of ‘smart baubles’ packed with sensors and ultra-low-power radio transmitters, the basal hydrology of the Greenland Ice Sheet can be traced.
A dual-rotor electric vehicle is currently being developed by engineering students with a view of competing at an upwind race in Denmark.
A largely untapped source of energy is the almost 26,000 impoundment structures or barriers that the UK Environment Agency has identified in UK waterways. The head loss in the water flowing over or through these barriers represents a significant opportunity for hydro-power generation if a technology could be found to retro-fit to these structures. World-wide, there is an urgent need for small, low-head, run-of-the river power generation systems, that can be plugged together to form independent but reliable energy networks. The Group is researching both the generation and the networking methods for such systems, and working with charities such as Engineers Without Borders to assure successful deployment.
