Energy Neutral Wireless Sensing for Server Farms Monitoring

Energy harvesting techniques are consolidating as effective solutions to power electronic devices with embedded wireless capability. We present an energy harvesting system capable to sustain sensing and wireless communication using thermoelectric generators as energy scavengers and server's CPU as heat source. We target data center safety monitoring, where human presence should be avoided, and the maintenance must be reduced the most. We selected ARM-based CPUs to tune and to demonstrate the proposed solution since market forecasts envision this architecture as the core of future data centers. Our main goal is to achieve a completely sustainable monitoring system powered with heat dissipation of microprocessor. To this end we present the performance characterization of different thermal-electric harvesters. We discuss the relationship between the temperature and the CPU load percentage and clock frequency. We introduce a model to simulate the power characteristic of the harvester and a prototype has been realized to demonstrate the feasibility of the proposed approach. The resulting system achieves a minimum 5 min sampling frequency of environmental parameters such as temperature, humidity, light, supply voltage, and carbon-monoxide/volatile organic compounds gases using a MOX sensor mounted on a commercial wireless node with a power budget in the microwatt range.