Download Pyroelectric-Based Solar and Wind Energy Harvesting System

Pyroelectric-Based Solar and Wind Energy
Harvesting System
Abstract :
Inherent scarcity of thermal sources with a time varying temperature profile is the reason
why the pyroelectric- based energy harvesting is not as prominent as its counterpart,
thermoelectric generators, in the thermal energy harvesting domain. In this paper, a practical
solution for generating thermal oscillations required for sustainable pyroelectric-based energy
harvesting from the solar and wind energies, is presented. The main focus of the work is to
modulate the concentrated solar radiation using a vertical axis wind turbine for producing higher
rate of change of temperature on the pyroelectric material. The maximum energy and power
density produced by the prototype device using PZT-5H as pyroelectric material are 6.927
mJ/cm /cycle and 421.18 W/cm , respectively, and on average it can produce a power density of
304.78 W/cm , which concurs with the theoretical model.
Objective:
In this paper, a pyroelectric-based energy harvesting system which converts the radiant
energy from the Sun into useful power is designed and tested. The principle aim of the present
work is to maximize the rate of change of temperature of the pyroelectric material, as it directly
influences the power output from the pyroelectric material using the freely available solar and
wind energies. A well-known technique to increase solar intensity by means of concentrating
solar collector based on Fresnel lens and the mechanical input from the Savonius wind turbine
are combined to produce the desired large rate of change of temperature on the pyroelectric
material PZT-5H. The distance between the pyroelectric material and Fresnel lens are adjusted to
keep the maximum temperature of the active material well within its Curie temperature during
testing
Existing system
The solar thermoelectric generators make use of the Seebeck effect to generate voltage
from a spatial thermal gradient. Instead, the temporal changes of thermal energy can be captured
by means of pyroelectricity. The existence of spontaneous polarization, which is a permanent
electric dipole moment with a specific crystal axis, is the basic constraint for a material to exhibit
pyroelectricity. It is the vulnerability of this spontaneous polarization to thermal changes which
leads to charge redistribution on the surface of the material resulting in a current flow in an
external circuit and thus creating a physical phenomenon called pyroelectricity.
There have been many studies related to pyroelectric-based energy harvesting mostly
involving the Olsen cycle [4], which is based on the thermodynamic Ericsson cycle, with two
isothermal and two isoelectric field processes. This cycle has been realized for different materials
like polymers, single crystals, and relaxor ferroelectrics and for different electrical fields and
temperature ranges. It should be noted that the presence of an electric field allows the
thermodynamic cycle to operate around the Curie temperature where phase transition occurs
between the ferroelectric and paraelectric and subsequent large changes in polarization.
Proposed system
In this paper, a new solar energy harvesting system through pyroelectricity, which does
not require any external means to generate thermal fluctuations other than wind energy, is
proposed. The principle of the proposed energy harvesting system relies on the increased
intensity of solar radiation on the pyroelectric material by means of an optical concentration
system. By concentrating solar radiation, higher temperature can be achieved which may not be
possible by normal exposure to solar radiation. And this incident concentrated radiation on the
pyroelectric material has to be modulated in order that the pyroelectric material heating is
periodic.Modulation can be achieved by means of a rotating mechanical chopper disc which is
placed in between the optical concentration system and the pyroelectric material.
Block diagram
The energy required to rotate the chopper can be derived from the kinetic energy of the
wind by means of a wind turbine attached to the optical concentration system. The mechanical
energy input from the wind turbine is transmitted to the chopper disc using a belt drive
mechanism via a speed reduction unit. The speed reduction unit is necessary in order to reduce
speed of rotation of the chopper disc, so that the active material will have a longer period of
heating and cooling resulting in a high rate of change of temperature. Further, a heat sink is
placed under the pyroelectric material with good thermal contact to passively cool the material
during the cooling phase of the thermal cycle
ADVANTAGE
 light weight,
 more compact,
 low cost