A device including a liquid's flow path having an upstream side and a downstream side, a plurality of flow restrictive elements providing material communication between the upstream side to the downstream side, a thermoelectric generator or a thermophotovoltaic cell in thermal connection with a portion of the device located at the downstream side with respect to the plurality of flow restrictive elements. The portion is provided with roughness elements for, in use, contacting a fluid flowing through the device and facilitating collapse of cavitation bubbles.