Pencil and paper convert heat to electricity
17th February, 2018: Helmholtz-Zentrum Berlin für Materialien
und Energie (HZB), Germany has come out with an inexpensive and environmentally
friendly way of producing electricity from heat with the simplest of
components: a normal pencil, photocopy paper, and conductive paint. The
temperature difference produced between the media is converted into electricity
via the thermoelectric effect.
Thermoelectric materials need to have low thermal conductivity despite their high electrical conductivity. This is seldom realizable, since ordinarily both thermal and electrical conductivity vary similarly.
The materials used today to develop thermoelectric devices include inorganic semiconductor materials such as bismuth telluride. But they are extremely expensive to produce and toxic. Some flexible, non-toxic, organic materials based on carbon nanostructures are also being investigated for use in the human body.
A team of scientists of HZB, under the leadership of Prof. Norbert Nickel have identified a simple mechanism for developing photoelectric effect. They developed two materials; one based on a normal HB-grade pencil, covered by ordinary photocopy paper and the other based on conductive co-polymer paint applied on to the surface of the paper. The new system produced electricity at par with the more expensive nanocomposites as used today, which could be increased tenfold by adding some indium selenide to the graphite from the pencil.
This invention helps us to print thermoelectric components onto paper that are extremely inexpensive, environmentally friendly, and non-toxic. These tiny and flexible components could also be used directly on the body and could use body heat to operate small devices or sensors.