The electrothermodynamic cycle is described by the loop of the electric displacement, D , versus the electric fi eld, E ( D-E loop). In Figure 1 a, a schematic of the theoretical Olsen cycle is presented as ABCD. The cycle begins at a low temperature ( T low ) with no electric fi eld (point A). When the electric fi eld ( E 1 ) is applied, the state moves to point B (path AB), corresponding to the hysteresis loop section of the material obtained at T low (see Figure S1b, Supporting Information), denoting an increase in electric displacement. The temperature is increased to the value T high (path BC). Then, electric displacement corresponds to another hysteresis loop, obtained at T high (point C). Removing the external electric fi eld, the state moves to point D along the hysteresis loop at T high (path CD). Finally, the temperature is decreased to T low , and the state moves to point A (path DA). The produced loop area is considered as an energy density ( N D , the area of the D -E loop); the power density ( P D , = N D f ) is also evaluated from the area. [7][8][9][10][11][12][13][14] To the best of our knowledge, there is no application that satisfi es a true energy breakeven because of the diffi culties associated with fi nding a suitable energy source that can simultaneously give alternative heat and an electric fi eld. [7][8][9][10][11][12][13][14] In this study, a novel electrothermodynamic cycle is presented based on temporal temperature variation to obtain practical net energy from exhaust heat of automobile. Another representative heat electric conversion cycle, the Stirling cycle, is modifi ed, and this cycle has a higher potential than the Olsen cycle. [ 6,7 ] The most representative pyro and piezoelectric material, PZT (C-6, Curie temperature T C : 305 °C), is employed. The temperature variation is considered as a simple pseudo-sinusoidal wave based on the imaging of the temperature fl uctuation of the exhaust gas. An external electric fi eld is applied to the material corresponding to the temperature variation (see details in the Supporting Information). The general Sawyer-Tower (ST) circuit is redesigned by inductions of a Diode and a SWitch (named as DSW circuit, see Figure S2b, Supporting Information) to evaluate the D-E loop and simultaneously harvest the net energy.In Figure 1 a, a schematic of our cycle (ABC 1 D) is shown. The AB path is the same as the Olsen cycle. The material is then isolated and the electric displacement D is kept constant while the temperature is increased to T high . The voltage is increased to the E 2 value (path BC 1 ) based on the electrothermodynamic equation: [ 15,16 ] and p are the electric displacement, electric fi eld, temperature, dielectric permittivity, time, and pyroelectric coeffi cient, respectively (see details in the Supporting Information). Then, the material is reconnected to the circuit, and the state moves to point D (path C 1 D). Finally, temperature is decreased back to T low , and the D-E loop is closed. The triangular area BC 1 C is the additional ...

according to a given temperature variation during generating cycle:It was indicated that the D F could be effective as a FOM for the pyroelectric generating performance and the dielectric loss (tanδ) significantly affected the generating performance in addition to p under hightemperature and electric-field conditions. Furthermore, of the PZTs tested, the C-91 sample (see further), which showed the highest generating performance, resulted in a generated energy of 1.3 mW cm −3 in the engine dynamometer assessment. This is 13 times greater than the generated energy reported in a previous study of C-6 (0.1 mW cm −3 ). [1] How much wasted heat exists, and how can we utilize it as renewable energy? These questions have been explored in automotive applications. Recently, there has been increasing interest in thermoelectric generation as an energy-regeneration technology because of the increasing concerns about environmental pollution and commitments to a low-carbon society.Therefore, to improve the fuel efficiency (energy saving) of automobiles, in this study, we focus on exhaust losses (exhaust gas), which account for approximately 30% of the gasoline energy, which is equal to the driving energy, [2] and developed an exhaust energy-regeneration technology based on thermoelectric generation.In pyroelectric applications, the general figures of merit (FOMs) have been applied and reported near room temperature. We derived the modified FOMs in considering our electro-thermodynamic cycle for the usage environment of automotive applications. The relationship between the material properties and generating performance of PZTs was investigated at various temperatures. The F D was suggested from F D , a FOM for a pyroelectric sensor, based on the modified pyroelectric coefficient (p); p . p was calculated by the change of the spontaneous polarization (P S ) according to a given temperature variation during one cycle; ΔP S /ΔT (T max −T min ). It was indicated that the F F D D could be effective as a FOM for the pyroelectric generating performance and the dielectric loss (tanδ ) significantly affected the generating performance in addition to p p under high-temperature and electric field conditions. Furthermore, of the PZTs tested, C-91 sample which showed the highest generating performance resulted in a generating energy of 1.3 mW cm -3 in the engine dynamometer assessment. This is 13 times greater than the generating energy reported in a previous study of C-6 (0.1 mW cm -3 ).In pyroelectric applications, general figures of merit (FOMs) have been applied and reported at near room temperature. We derived modified FOMs for the usage environment of automotive applications by considering an electro-thermodynamic cycle. The relationship between the material properties and the generating performance of lead zirconate titanates (PZTs) was investigated at various temperatures. A general FOM F D for a pyroelectric sensor, quantifying the electrical noise caused by thermal energy (Johnson noise) was modified and suggested as D

The "SMAC module" is a low-cost, high-efficiency photovoltaic module that integrates three techniques: a "SMart stack," "Areal current matching," and "solar Concentration." This paper presents the result of a proof-of-concept study of the SMAC module conducted using device simulations and indoor experiments. The simulation results show that an SMAC module with a two-terminal GaAs/Si tandem solar cell can achieve an efficiency of approximately 30% and superior electricity generation per unit top cell area. The performance of the GaAs/Si solar cell developed in this study is similar to that of a GaAs/InGaAsP solar cell under concentrated artificial sunlight and is consistent with the simulation results.

A waste heat recovery system is investigated basically. Original electro-thermodynamic cycle and novel system are expected to be viable in any heat sources with time dependent temperature changes instead of the spatial temperature gradient.

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