Nanotechnology used to reduce
cost of thermoelectric generators
Materials that generate energy from
waste heat could help to produce more fuel-efficient cars and power plants.
Thermoelectric generators (TEGs)
produce electricity from a temperature difference between two types of
electrical conductors, in a process known as the Seebeck effect.
Since the devices have no moving
parts, they are extremely reliable. However, they typically require the use of
toxic or scarce materials, limiting their use to niche applications such as
powering space probes, for example.
Now a UK research team, led by Dr
Jan-Willem Bos at Heriot-Watt University in Edinburgh, is attempting to use
nanotechnology to reduce the cost of thermoelectric generators, allowing them
to be used in a wider range of applications.
The team, which also includes researchers
from Glasgow and Royal Holloway Universities and Leicestershire-based European
Thermodynamics, will focus on so-called Heusler alloys, which contain
combinations of abundant metals such as nickel, titanium and tin.
The researchers hope that by manipulating
the nanostructure of the alloys they will be able to increase their energy
conversion efficiency to that of more toxic materials.
To achieve good thermoelectric
efficiencies, a material must have a high Seebeck coefficient, as well as low
electrical resistivity and low thermal conductivity, said Bos.
Heusler alloys typically have a high
Seebeck coefficient and low electrical resistivity, but a high thermal
conductivity.
The researchers plan to alter the
nanostructure of the alloys, to create a semiconducting matrix, with inclusions
of a metal inside this matrix, said Bos. “This creates interfaces inside the
material, which can be used to reduce its thermal conductivity, and that is
important to achieving good thermoelectric efficiencies,” he said.
The devices could be embedded in car
exhaust systems, where they could generate electricity from the waste heat.
This in turn would allow the size of the alternator to be reduced, improving
fuel efficiency.
The most efficient TEG for the
temperatures found inside car exhausts is a compound of toxic lead and rare
tellurium, said Bos. “That is a non-starter for practical applications, so we
are trying to get similar performance, but from something that is a bit more
feasible,” he said.
The technology could also be used to
generate electricity from waste heat from power plants, for building combined
heat and power units for remote locations, and to replace batteries in wearable
microelectronics.
European Thermodynamics will build
prototype TEG devices as part of the project.
Comentários
Enviar um comentário