Industrial control and automation is not an obvious application for energy harvesting, although machinery, by its very nature, is an obvious source of energy, ripe for harvesting.
Nevertheless, why exploit energy harvesting in a plant or factory environment? Consider that two of the major trends affecting the industrial automation sector between now and 2015, according to Frost & Sullivan,¹ are energy efficiency (sustainability) and the integrated enterprise (networked automation). Incoming legislation for electric motors is one of the more pressing drivers of the first trend. The need to improve overall efficiency to remain competitive is stimulating the second.
So far, so good, but where does energy harvesting fit in? Wireless sensor networks have been found to deliver a host of technical, logistical, and commercial advantages in industrial monitoring, control, and automation applications. The employment of energy harvesting techniques to power these networks, thereby making them autonomous, is fast becoming a compelling dynamic. This combination of technologies can address both challenges facing the industrial automation sector: energy efficiency and networked automation.
This article will provide some insight into how these emerging technologies can be deployed with great advantage in control automation applications. A consideration of typical system construction will be followed by examples of complementary components that together can form a comprehensive solution. These include LTC3108/9 power management and LTC3588 power supplies from Linear Technology, ultra-low power Gecko microcontrollers from Energy Micro, MAX17710 power management IC from Maxim Integrated Products, Thinergy microenergy cells from Infinite Power Solutions, piezoelectric transducers from Midé, Ultracap supercapacitors from NessCap, and a development system combining some of these devices from Würth Electronics.
Industrial automation market
The availability over recent years of small, low cost, wireless sensors that can be reliably connected via a standards-based network has opened up a realm of new applications in areas such as smart buildings and industrial control, among many others. No longer the sole domain of remote applications, such as oil and gas pipelines, wireless systems are being increasingly installed throughout factories and plant networks to improve operational and energy efficiency.
A recent report from ARC Wireless for Process Manufacturing² predicted growth of 32% CAGR, reaching $1.1 billion in 2012. The appeal, according to ARC, is the ability to deploy sensor nodes that connect reliably to standard industrial network protocols, which themselves connect to higher-level networked process control systems.
In terms of wireless network technology, there are many industry standards emerging, some finding more appeal in certain markets, such as ZigBee in home automation. In the industrial, control and automation sector, the meshed architecture of the industry standard WirelessHART network provides a robust solution for wireless sensor networks in many installations. It has widespread and growing industry support and a substantial ecosystem of suppliers.
Market researchers cite WirelessHART as the most prolific wireless protocol used in industrial applications. Further, the recent announcement that the Hart Communication Foundation, Fieldbus Foundation, and Profibus & Profinet International have joined forces to ensure standard bi-directional communication between their systems has increased manufacturer confidence in the technology.
The ability to install autonomous wireless sensor networks, which harvest energy from ambient sources, in industrial control applications is the critical factor here. Whether the wireless network protocol used for the wireless sensor network is one of the many industry standards available, or whether it transmits directly to the WirelessHART network, is less material.