In the presence of limitations in the availability of energy for data centres, especially in dense urban areas, a novel system that we call an Energy Packet Network is discussed as a means to provide energy on demand to Cloud Computing servers. This approach can be useful in the presence of renewable energy sources, and if scarce sources of energy must be shared by multiple computational units whose peak to average power consumption ratio is high. Such a system will use energy storage units to best match and smooth the intermittent supply and the intermittent demand. The analysis of such systems based on queueing networks is suggested and applied to a special case for illustration.