Proponents of the notion that cloud computing delivers green benefits have developed a compelling argument. Based on the idea that the cloud represents the most efficient way of providing compute resources, the starting point for the green cloud argument is illustrated in the following well known graphic. In the figure, Amazon has drawn a capacity-utilization curve to demonstrate how on-demand services more closely align with actual usage – thereby avoiding the over-provisioning of computing resources. As Amazon CTO Werner Vogel explained at the most recent Uptime Institute Symposium, “Server utilization rates with some of their enterprise customers as low as single digits – with cloud, can always surpass an enterprise, and achieve maximum utilization. The benefits are what it’s all about. You reduce capital as well as operational expense. The reduction in operational expense comes from the fact that you do not run things. You do not use resources if you do not run them.”
Vogel’s “resource” reference is to server hardware and software, but also to the energy that powers them. In a whitepaper commissioned by Microsoft
, and authored by Accenture and WSP Environment & Energy consultancies, cloud computing was found to have a significant impact on energy use – and the resulting carbon emissions. Through comparison of the energy use per user for Microsoft Exchange Server 2007, Microsoft SharePoint Server 2007 and Microsoft Dynamics CRM and their cloud-based equivalents, the authors calculated energy savings in the range of 30%. In the case of smaller deployments (the study considered deployments of 100, 1,000 and 10,000 users), savings were even more substantial: when a smaller organization moved to the cloud, energy and carbon savings approached 90% as compared to running the same applications on on-premise server, network and storage infrastructure. In the study, reduced energy consumption was attributed to four key factors: dynamic provisioning, which matches server capacity to demand; multi‑tenancy, which allows thousands of companies to simultaneously share on massive public cloud infrastructure; improved server utilization, which enables performance of higher workloads with a smaller infrastructure footprint; and innovation in data centre design, targeted at minimizing facility energy use by large cloud providers.