We have discussed about the cloud computing in the environmental point of view and we explored the concept of Green Cloud Computing. Then we explored the general deployment model of Cloud computing and the Concept of Virtualization. Then we explored the security framework for the pool of Virtual Machines (VM), the authentication and the trust management and policy enforcement into the system. Then we explored the trust management or authentication mechanism for multiple pool system. Then we said that the virtualization technique is the best solution for making the green cloud computing and the use of virtualization can be the most beneficial which includes load balancing, resource management , server utilization and the most importantly, power savings. That makes the ordinary data centre Cloud Computing, the „Green‟ Cloud Computing