Harvesting Energy from waste heatusing pyro electric
• 36.2% of the energy contained in raw energy sources is useful.
• 57.8% is wasted mainly in the form of heat. • The efficiency in transport sector is only 20-30
%.
Energy Harvesting
• Wind• Water• Solar• Temperature• Vibration
Energy Harvesting Mechanisms
• Piezoelectric energy harvesting• Electrostatic energy harvesting• Thermoelectric energy harvesting• Photonic energy harvesting • Pyro electric energy harvesting
PiezoelectricPiezoelectricity is the ability of certain materials to produce a voltage when subjected to mechanical stress.
Piezoelectric materials also show the opposite effect, where application of an electrical field creates mechanical stress (size modification) in the crystal.
The Piezoelectric Effect
• the ability of certain materials to generate an electric charge in response to applied mechanical stress or vice versa.
PIEZOELECTRIC EFFECT
Sound waves striking a PZ material produce an electrical signal
Can be used to detect sound (and echoes)!
REVERSE PIEZOELECTRIC EFFECT
Applying an electrical signal causes the PZ element to vibrate
Produces a sound wave
Application of Piezoelectric
• POWER GENERATING SIDEWALK• GYMS AND WORKPLACES• POWER GENERATING BOOTS OR SHOES
Pyro electric
Pyro electric energy conversion offers a novel and direct way to convert heat into electricity
Pyro electric effect
• The displacement of the atoms from their equilibrium positions upon heating and cooling results is a result of the pyro electric effect.
• Changes in temperature cause proportional changes in the electric displacement
Pyroelectricity
• the ability of certain materials to generate a temporary voltage when they are heated or cooled.
Pyro electric material
• The most important component in pyroelectric energy conversion is the pyroelectric material.
Performance of pyroelectric materials
• Large pyroelectric coefficient in order to generate a large pyroelectric current
• Large spontaneous polarization so that more charges can be stored on the material’s surface to produce a large pyroelectric current.
• Large dielectric strength to enable large applied electric field during the Olsen cycle without breakdown.
• Small leakage current caused by electrical conduction through the material that reduces the energy density.
• Short discharge time of the surface charges in order to minimize cycle period and to maximize power density.
• Small heat capacity to enable rapid isoelectric heating and cooling processes of the Olsen cycle to maximize power density.
Harvesting of waste heat using pyro electric material
Conculsion
• dealing with small-power energy harvesting from heat, it can be achieved using both thermoelectric and pyroelectric effects
• Temperature gradients are necessary, which is just the main difficulty of thermoelectric energy harvesting. In case of pyroelectric energy harvesting, a time varying temperature is necessary.
• or instance, using a limited temperature gradient due to the limited heat exchange, a maximum efficiency of 1.7% of Carnot efficiency can be expected using a thermoelectric module. On the contrary, a pyroelectric device may reach an efficiency up to 50% of Carnot efficiency