Converting Heat to Electricity? Sounds Good!

Category: Green Electricity Production | 22/05/2009 - 05:16:47

Most people are aware of renewable energy sources - hydro, wind and solar power – along with the advantages they offer the environment compared to processes like industrial fossil fuel burning (a known contributor to climate change).

New Source of Renewable Energy

Scientists in the US, however, have recently been developing technology which, in the words of one, provides electricity from “a new source of renewable energy” – waste heat.

Based at the University of Utah, the scientists have been coming up with methods of lowering household energy consumption by indirectly transforming heat into electricity. Technology like this could ultimately lead to new advances in renewable energy use in the home, and could also have military applications. Additionally, it could work in tandem with other types of technology, such as PCs which, as they get ever-more advanced and sophisticated, require more powerful cooling devices.

The head scientist involved in the electricity-from-heat venture is Professor Orest Symko who, four years ago, launched a project called TAPEC (Thermal Acoustic Piezo Energy Conversion), in partnership with scientists based at the University of Mississippi and at Washington State University.

Thermo Acoustic Piezo Energy Conversion

Thermo Acoustic Piezo Energy Conversion

Here’s a brief explanation of exactly what ‘Thermal Acoustic Piezo Energy Conversion’ - as exploited by Professor Symko and his colleagues - actually refers to.

Thermal Acoustic (or ‘Thermoacoustic’) devices are a type of technology capable of either:

  • Drawing on sound waves to drive heat from location A to location B
  • Capitalising on the difference between two temperatures to create sound which can, subsequently, be turned into electricity by introducing a piezoelectric device.

‘Piezo’ is a Greek term meaning to apply pressure to, or to press. Piezoelectric, therefore, refers to the way in which certain materials can generate a current when pressure is applied to them.

Symko’s heat to electricity conversion technology involves two processes, then. Firstly, thermoacoustic devices (known as heat engines) convert heat into sound. Secondly, piezoelectric devices convert this sound into electricity when pressure is applied to them. Symko himself compares the effects of pressure on piezoelectric devices to hitting your elbow – a sudden, painful impulse.

TAPEC Electricity

Professor Symko has drawn attention to how the electricity created as a result of Thermo Acoustic Piezo Energy Conversion (TAPEC) could actually be used. Potential applications include a number of areas in the home, where the TAPEC electricity could replace that produced by household photovoltaic devices, like solar panels, which draw on the energy in the sun’s rays, and for which another term is ‘solarelectric.’ Small TAPEC devices could also be incorporated into PCs or laptops, which could draw on the machines’ internal heat to produce electricity from and which, in turn, the PC or laptop could derive power from – thus creating a satisfying and efficient renewable energy circuit.

TAPEC electricity could also have military applications and, recognising this, the US military is involved in the Utah team’s research - the US Army having injected finance into the venture. Technology capable of providing a combat edge within a conflict zone could obviously prove highly advantageous to those that own it and, according to Professor Symko, the US Army is keen on “taking care of [i.e. utilising] waste heat from radar, and...producing a portable source of electrical energy which you can use in the battlefield to run electronics.”

Another application is within the manufacturing industry. The purpose of industrial cooling towers is to remove the heat associated with industrial processes. Rather than have this waste heat pass into the atmosphere, however, the Utah scientists propose drawing on it and applying TAPEC technology in order to create electricity.

“We are converting waste heat to electricity in an efficient, simple way by using sound”, Symko says.

“It is a new source of renewable energy from waste heat.”

Advantages of TAPEC

Among the advantages of TAPEC technology is the fact that it generates little or no noise pollution. According to Symko, once the devices are able to be made more compact, they will able to transform heat into sounds that the human ear cannot detect (ultrasonic). What’s more, the sound-to-electricity conversion processes already involves an inherent loss of volume anyway. Finally, the sound can be reduced through the application of muffling devices.