The field of sintering has experienced in the last decades an increasing improvement to satisfy the industrial, scientific and social demands. Recently, Field Assisted Sintering Technologies (FAST) have achieved interesting developments towards low temperature densification of functional materials. The challenge to face is the fabrication of more and more sophisticated materials with controlled functional properties while reducing the environmental footprint. Even if leadbased perovskite materials such as Pb(Zr,Ti)O3 (PZT) are still largely investigated because of their unrivalled piezoelectric properties, research is currently focusing on environmentally friendly materials such as lead-free piezoceramics. In this work, our strategies towards lowering the sintering temperature of the lead-free KNN ((K,Na)NbO3) piezoelectric ceramics by Spark Plasma Sintering (SPS) will be shown and evaluated in terms of density, structure/microstructure control and dielectric and piezoelectric properties. Furthermore and aiming an integration of KNN as the active material in Energy Harvesting MEMS, some results of co-sintering KNN screenprinted layers on a metal substrate will be shown. The main challenge is to develop sintering strategies for low temperature processing of vibration energy harvesters using piezoelectric MEMS which are effective, low-cost and with smaller impact on the environment.