Applications of low-cost wireless sensing are increasing in the power industry. With the addition of energy harvesting capability, the sensors become easy to deploy, install and retrofit to existing equipment. This paper will summarize progress on low-cost, easy-to-deploy, self-powering wireless sensor nodes integrated with existing solutions into wireless sensor networks, to monitor the temperature of selected equipment in an industrial power plant (motor, pump, etc.). Temperature data is important for monitoring the operating conditions of the equipment. Each sensor node includes: (a) energy-harvesting device and transducer, which converts the vibrational motion of the equipment into electricity, made by a piezoelectric material; (b) a power management circuit with cold start function for AC to DC, DC to DC, and voltage regulation; (c) temperature sensor; (d) an ultra-low power wireless communication unit using ZigBee protocol. The quiescent current consumption of the circuit is calibrated to be less than 15 µA, and the sensor and RF transmitter have an average current consumption of less than 10 µA. Multiple sensors in a network communicate with a powered hub unit intermittently while continuously harvesting and storing energy, maintaining always-on operation without external energy input. A robust packaging method is developed for easy installation and facile retrofitting in the relevant industry environment. The temperature information of an equipment is monitored for about 2 months. We demonstrate that the self-powering wireless sensor node can be implemented in a generic industrial power plant equipment with minimal cost and effort for maintenance while providing real-time temperature sensing and long-term, continuous monitoring.