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Wireless Applications

Perpetuum and CAP-XX Develop Battery-Free Condition Monitoring

June 3, 2008

The system combines a vibration energy–harvesting microgenerator and a supercapacitor, which together collect and store enough energy to transmit sensor data over wireless networks.


IRVINE, CA /BUSINESS WIRE/ -- On June 3, engineers from U.K.-based Perpetuum and Australia-based CAP-XX Ltd. will describe how Perpetuum's PMG17 vibration energy-harvesting microgenerator, together with a CAP-XX supercapacitor, allow wireless sensor system manufacturers to design battery-free condition monitoring systems that collect and report on machinery for improved asset management. They will also present the results of a field trial at the Nyhamna gas plant in Norway to evaluate the system in a challenging industrial environment.

Plants and refineries monitor pumps, machines, and processes to ensure optimum safety, up time, and efficiency. Condition monitoring solutions have traditionally involved maintenance engineers walking around to collect data, or the use of battery-powered wireless sensors. Engineers' time is valuable, and batteries may survive only two to five years in such harsh environments. So in plants with thousands of battery-powered wireless sensor nodes, the cost of replacing and disposing of batteries is significant.

Supercapacitor Complements Microgenerator
The PMG17 microgenerator converts unused mechanical vibration into useable electrical energy. After being stored in a CAP-XX supercapacitor, the energy can power wireless sensor nodes indefinitely.

The supercapacitor stores the energy harvested by the PMG17 microgenerator (a low but steady source of between 0.5 mW and 50 mW) and then delivers the peak power needed to transmit sensor data over wireless networks, such as IEEE 802.15.4 (Zigbee) and 802.11 (WLAN). The output of the microgenerator can easily cover the power needs of intermittent radio sensor systems, such as Wireless HART, SP-100, and Wi-Fi in industrial applications, but its output impedance is too high to supply the tens to hundreds of milliwatts required by sensor nodes during data collection and transmission. The high-capacitance and low-equivalent series resistance of the supercapacitor provides approximately one second of peak power to transmit data.

"The microgenerator and supercapacitor combination eliminates battery-reliability issues and time-consuming maintenance while enabling significant savings in operational costs and energy use," said Dr. Stephen Roberts, Technical Manager for Perpetuum.

CAP-XX Vice President of Applications Engineering Pierre Mars will present the collaborative paper, which was co-authored by Perpetuum Senior Engineer John Parker, at the Darnell nanoPower Forum, June 2–4 in Irvine, CA.

Mars commented, "Wireless system manufacturers can now easily design battery-free systems using this fit-and-forget self-generating power source."

During a field trial, the Nyhamna gas plant in Norway used the PMG17 and CAP-XX supercapacitors to power wireless sensor nodes in its network, which is now operational. Operating faultlessly despite a wide range of temperatures, the sensors monitored the condition of rotating equipment, the main culprit in production shutdowns, reporting temperature and overall vibration every 5 min.

An application note to aid engineers designing self-powered wireless condition-monitoring systems is available for download from Perpetuum.

For more information, contact sales@cap-xx.com by email.






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