Sensor-Cloud is an emerging technology and popular paradigm of choice in systems development for various real-life applications. It consists in integrating wireless sensor networks with cloud computing environment. In fact, the cloud provides new opportunities of massive data storage, processing and analysing that wireless sensor networks can not offer. Despite the fact that the cloud have helped to overcome many wireless sensor networks limitations, there are other challenging issues that need to be addressed. The major problem that can significantly affect Sensor-Cloud performance is the short lifetime due to limited energy supply of sensors and sometimes some sinks. In this work, we propose a Sensor-Cloud Optimization problem (SCL-OPT) that maximizes lifetime as well as increases energy efficiency of sensors and sinks layers.