Lead-free ferroelectric ceramics (1-x)(Ba0.7Ca0.3)TiO3-xBa(Zr0.2Ti0.8)O-3 (BCTZ100x) with x=0.20, 0.30, 0.40, 0.50, 0.60, 0.70, and 0.80 were evaluated for their pyroelectric energy harvesting performance, using the Olsen cycle. As the composition ratio x increased, the crystal phase changed to tetragonal, orthorhombic, rhombohedral, and cubic; the phase boundaries crossed each other in the vicinity of BCTZ70. The crossover phase transition behavior between first-order and diffuse phase transition changed to only the diffusion phase transition with increasing x. A pinching effect occurred because an increase in dielectric constant was also observed. Energy densities N-D of 229mJ/cm(3) and 256mJ/cm(3) for BCTZ50 and BCTZ80 were obtained, respectively, in temperature of 30 degrees C-100 degrees C and an electric field of 0-30kV/cm. These N-D values are over two times higher than that of soft-Pb(Ti,Zr)O-3 (PZT), which exhibits piezoelectric performance equivalent to BCTZ50 at room temperature. Compared with soft-PZT, BCTZ50 and BCTZ80 exhibited larger N-D values owing to their lower Curie temperatures (T-C similar to 50 degrees C-110 degrees C). We conclude that low-T-C ferroelectrics are useful for pyroelectric energy conversion based on the Olsen cycle even if they are unsuitable for piezoelectric applications at high temperatures.