What products can we expect to see in the near future that use thermal energy harvesting?
21.04.2015
Part 2 of our interview with Dr John Allen on thermal energy harvesting
“Various forms of thermal energy harvesting are already in use and have been for some time. For example, geothermal energy is used in places like Iceland to produce electricity and hot water. Solar thermal collectors are being used to produce hot water, primarily for domestic use. High intensity solar collectors are being used to heat water to steam for power generation. Thermoelectric devices are used in space craft where they harvest heat given off by the decay of a supply of radioactive material. More recently thermoelectric modules have been fitted to domestic stoves for use in developing countries where electrical power is hard to supply, or not available, by other means. The same technology is also used in camping stoves for charging electronic devices and batteries in the field.”
“An increased demand for more sustainable energy and advances in energy harvesting technology, in particular developments in thermoelectric devices, mean we are likely to see thermal energy harvesting expanding into a wide range of new applications in the near future. Thermoelectric modules, and other energy harvesting devices, are finding their way into a range of wireless and other remote sensor and communication systems as replacements for batteries. This is partly because they offer a more environmentally friendly solution, and partly because they eliminate the need to replace a battery that has run out. This also makes it possible to place these systems where it would be impossible to replace batteries, such as harsh or hazardous environments. Thermoelectric generators are likely to be imbedded in the structure of aircraft to power wireless condition monitoring sensors scattered through them. In this application the use of energy harvesting reduces the requirement for wiring saving weight and cost. Thermoelectric generators are also being considered for powering wireless sensors in power stations, factories, pipe lines and district heating systems.
The emerging sector of wearable electronic technology also offers potential for thermoelectric energy harvesting by powering devices with body heat. A number of projects are on-going to place thermoelectric generators in vehicle exhaust systems to supplement or ultimately replace the vehicle’s alternator with the aim of increasing overall fuel efficiency. Some other thermal energy harvesting technologies are being considered for vehicle exhaust applications, but the majority are focused on thermoelectric generators. A wide range of energy harvesting technologies are also being considered for intelligence and defence applications.”
What needs to be taken into consideration when switching a product from using a battery to a thermoelectric generator?
“It may seem obvious, but the most important consideration when looking at switching to a thermoelectric generator is: ‘Do you have a temperature difference available for it to exploit?'
Assuming the operating environment of the device in question does offer a temperature difference from which to generate power, there are several other considerations to take into account:
- How much energy is available?
- What are the hot and cold side temperatures that the TED will experience? This is important as it will influence the thermoelectric material and device construction to be used
- How much power is required?
- What is the conversion efficiency of the TED to be used?
- How many TEDs are required and how many are there room for in the system?
- Is the temperature difference constant or does it vary or even cease to be for some of the time?
- Will a thermoelectric generator offer a cost effective solution for the specific application?
This concludes a two-part interview on thermal energy harvesting. For any further questions, including how a thermoelectric generator could replace a battery in your product, use the contact form or e-mail us at info@etdyn.com.
