Demand for Green services is increasing con- siderably as people are getting more environmental con- scious to build a sustainable society. Therefore, enter- prise and clients want to shift their workloads towards green Cloud environment offered by the Infrastructure-as- a-Service (IaaS) provider. The main challenge for an IaaS provider is to determine the best trade-off between its profit while using renewable energy and customers satisfaction. In order to address this issue, we provide a Cloud energy broker, which can adjust the availability and price combi- nation to buy Green energy dynamically from the market to make datacenter green. We investigate a simplified power model from where we can formulate and predict power demand. Our energy broker tries to maximize of using renewable energy under strict budget constraint whereas it also tries to minimize the use of brown energy by capping the limit of overall energy consumption of datacenter. The energy broker was evaluated with a real workload traced by PlanetLab. Experimental results show that our energy broker successfully keeps the best trade-off.