Christopher Gould

A comprehensive review of thermoelectric technology, micro-electrical and power generation properties

Thermoelectric technology may provide an alternative to traditional methods of power generation, heating and cooling. A small amount of electrical power can be generated by a thermoelectric module if a temperature difference is maintained between two terminals, or can operate as a heat pump, providing heating or cooling of an object connected to one side of the module.

A Review of Thermoelectric MEMS Devices for Micro-power Generation, Heating and Cooling Applications

Thermoelectric technology can be used to generate a small amount of electrical power, typically in the µW or mW range, if a temperature difference is maintained between two terminals of a thermoelectric module. Alternatively, a thermoelectric module can operate as a heat pump, providing heating or cooling of an object connected to one side of a thermoelectric module if a DC current is applied to the module’s input terminals. This chapter reviews the development of microelectromechanical systems (MEMS) based thermoelectric devices suitable for micro-power generation, heating and cooling applications. The chapter begins with a brief overview of thermoelectric technology, macro-thermoelectric module construction and operation. Micro-thermoelectric modules are introduced, and a review of recent developments in research, commercial development, and typical application of MEMS based micro-thermoelectric devices is made. The chapter draws conclusions on the development and potential application of MEMS based thermoelectric devices suitable for thermoelectric cooling, heating and micro-power generation.

Energy storage systems: A review of the technology and its application in power systems

Increasing implementation of renewable energy sources within power systems means that the use of energy storage technologies will be ever more important for system stability and power quality purposes. A range of energy storage technologies currently exist, ranging from low-power, short term technologies such as capacitors to long-term high power systems such as Pumped Hydro. Future developments such as the use of Carbon Nanotube technology within super-capacitors look set to bring improvements in power density, efficiency and lifetime.

Three Dimensional TCAD Simulation of a Thermoelectric Module Suitable for Use in a Thermoelectric Energy Harvesting System

Thermoelectric technology can be used to generate electrical power from heat, temperature differences and temperature gradients, and is ideally suited to generate low levels of electrical power in energy harvesting systems. This chapter aims to describe the main elements of a thermoelectric energy harvesting system, highlighting the limitations in performance of current thermoelectric generators, and how these problems can be overcome by using external electronic components and circuitry, in order to produce a thermoelectric energy harvesting system that is capable of providing sufficient electrical power to operate other low power electronic systems, electronic sensors, microcontrollers, and replace or recharge batteries in several applications. The chapter then discusses a novel approach to improving the thermoelectric properties and efficiency of thermoelectric generators, by creating a 3D simulation model of a three couple thermoelectric module, using the Synopsys Technology Computer Aided Design (TCAD) semiconductor simulation software package. Existing published work in the area of thermoelectric module modelling and simulation has emphasised the use of ANSYS, COMSOL and Spice compatible software. The motivation of this work is to use the TCAD semiconductor simulation environment in order to conduct a more detailed thermal and electrical simulation of a thermoelectric module, than has previously been published using computer based simulation software packages. The successful modelling and simulation of a thermoelectric module in TCAD will provide a base for further research into thermoelectric effects, new material structures, module design, and the improvement of thermoelectric efficiency and technology. The aim of the work presented in this chapter is to investigate the basic principle of thermoelectric power generation in the TCAD simulation environment. The initial model, and simulation results presented, successfully demonstrate the fundamental thermoelectric effects, and the concept of thermoelectric power generation. Future work will build on this initial model, and further analysis of the thermal and electrical simulation results will be published. This chapter begins with a short background review of thermoelectric technology, followed by an overview of a typical thermoelectric module’s construction, highlighting the main elements, material structure, and connection details for thermoelectric power generation. The chapter then discuses a generic design of a thermoelectric energy harvesting system that incorporates a thermoelectric module with a boost converter, low power DC to DC converter, and a supercapacitor. The 3D modelling of a thermoelectric module is then presented, including the simulation results obtained for the thermal and electrical characteristics of the device when it is connected as a thermoelectric generator. Different thermoelectric couple and module designs have been investigated, and the simulation results have been discussed with reference to fundamental thermoelectric theory. The chapter draws conclusions on the application of thermoelectric technology for energy harvesting, and the validity and effectiveness of the 3D TCAD thermoelectric module simulation model for thermoelectric power generation.

Thermoelectric technology: Micro-electrical and power generation properties

A thermoelectric test system for measuring micro-electrical power generation has been designed. Standard thermoelectric modules have been tested to determine their micro-electrical and power generation properties, with typical test results presented. A module can generate a small amount of electrical power, typically mW, if a temperature difference is maintained between two terminals, and can be used in energy harvesting systems or provide electrical power for wearable electronics. Alternatively, a thermoelectric module can operate as a heat pump, providing heating or cooling of an object connected to one side of the module.

Review of current and future electrical energy storage devices

This review considers and compares different energy storage technologies currently available. It also identifies how they can be used in varying applications such as energy harvesting wireless sensor networks, creating a sustainable electrical power system and helping to enable renewable technologies. It also offers insight into the potential future applications of energy storage systems that will secure sustainable energy generation in years to come, and the advances predicted to increase battery and capacitor capacity.

Review of wind farm power collection schemes

The main development trend of wind power generation systems is large offshore wind farms (OWFs) with grid connection. However offshore wind farms have grown rapidly due to much better wind conditions. Hence, several large scale offshore wind farms are planned to be built and installed at distances greater than 100 km from the coast. Traditionally, an AC collector scheme collects energy from the wind farm and step up the voltages by power transformers and transmit power via AC submarine cables to the onshore substation. However, this is suitable for shorter distances about 50 km. When the distances are greater the AC transmission of bulk power from the wind farm to the onshore grid via undersea cables is not viable due the reactive power issues. Therefore HVDC transmission is now being considered for the grid connection of wind farms. However as wind farms constitute weak systems Line commutated converter (LCC) based HVDC is not viable and newer Modular Multilevel Converter (MMC) based Voltage Source Converters(VSC) are needed for AC-DC conversion. Opting for dc systems for both power collection and transmission pose a number of technical challenges in terms of developing HVDC breakers and DC -DC converters.

An investigation of power flow control methods in multi terminal high voltage DC grids

Some significant problems prevent the formation of multi terminal high voltage DC grids until now. Absence of power flow control is considered one of the main challenges that have to be solved in the near future to allow building of an efficient DC grid. This paper investigates different power flow control methods. Simulation of series insertion of AC/DC converters is carried out using MATLAB/SIMULINK software package and results are discussed.

Review on micro-energy harvesting technologies

This paper presents an overview of energy harvesting, and describes the methods used to generate electrical power from ambient or waste energy sources and includes; photovoltaic; thermoelectric; piezoelectric; pyroelectric; radio frequency (RF); electromagnetic induction; electrostatic; and capacitive methods. A brief description of the scientific principles, typical application, commercial success, and future prospects is discussed. The paper concludes that photovoltaic energy harvesting is the most commercially successful energy harvesting technology to date, partly due to its high efficiency and power density. However, parallel technology developments in low-power boost and DC-DC power conversion, along with energy storage in electrical double layer supercapacitors, have enabled thermoelectricity, piezoelectricity, and electromagnetic energy harvesting to achieve commercial viability and increasing application success. In future, it is likely that a greater focus will be placed on the integration of these different energy harvesting techniques into one overall system, taking advantage of the individual strengths of each technique.

Real time simulation of a current flow controller for HVDC grid applications

Interconnecting several offshore wind farms using High Voltage dc (HVDC) connections and forming multi terminal HVDC grid are some of the targets set by industry leaders to be achieved in the near future. Researchers have introduced a few methods of power flow control based on either the control of AC/DC converter stations or the connection of new power electronic equipment to the grid. In this paper, the operation and control of an extended three-port IGBT based current flow control (CFC) device suitable for multi terminal HVDC systems is presented. Features and functionalities of the proposed controller including the balancing of cable currents, limiting the magnitude of cable current and current nulling are demonstrated. The proposed three-port CFC is real time simulated using OP4510 real time simulator. Real time simulation studies explore fast dynamic response and the results show that the CFC studied may have a significant role to play in the control a of power flows in multi terminal high voltage DC systems.