Energy harvesting wireless technology is important for realizing interconnected M2M systems more reliably, conveniently, and economically while utilizing existing communication technologies.
Machine-to-Machine (M2M) communication enables equipment to interact with other equipment without human intervention, creating an intelligent network that automatically manages everyday tasks in production, logistics, monitoring, or smart buildings. This has to work infallibly, even in complex installations, because M2M requires open, standardized technologies that can be seamlessly networked to form a system.
Different wireless standards, such as GSM, Bluetooth, and Wi-Fi can be used for this purpose, because these standards support M2M applications where large volumes of data must be transmitted quickly. However, the high data rate comes at the price of high energy demand at the remote node, which requires a continuous supply of power either over cables or using high-capacity batteries. For smaller devices, such as sensors for detecting data, these technologies are suitable to a point, especially when measured data from many different points must be available to an intelligent controller.
From Building Automation to M2M
An increase in common building automation wireless standards are coming into play for M2M communication, because the more extensive the network, the more devices need to be integrated – and as easily as possible. Protocols such as KNX, LON, BACnet, and DALI are used to automate lighting, HVAC shades, and security systems. Sensors detecting temperature, moisture, occupancy, or CO2 provide data to the automation systems so they can properly control the building and its energy consumption.
It is not much of a stretch to go from building automation to an M2M system. Facility managers can integrate and network building services, multi-media devices, and other technological areas into the building automation system, while controlling them from mobile devices. This building automation principle can also be transferred to other automation processes, such as industrial control or logistics.
Traditionally, wireless solutions required power cables or batteries, which can be a drawback in complex M2M applications. Depending upon the application, batteries last for a limited time and must be replaced and disposed of properly. In a large system, this can be costly and lead to downtimes.
Energy harvesting wireless technology can overcome this challenge by connecting a large number of batteryless and maintenance-free sensors into existing Wi-Fi or mobile networks. Energy harvesting wireless technology stems from a simple observation where sensor data resides, sufficient ambient energy exists to power sensors and radio communications. Harvestable energy sources include motion, indoor light, and temperature differentials. These sources provide sufficient energy to transmit and receive radio signals between wireless switches, sensors, actuators, and controllers, sustaining vital communications within an energy management system. Instead of batteries, miniaturized energy converters generate power for the wireless communication devices.
The radio protocol is standardized as ISO/IEC 14543-3-10, uses sub one GHz frequency bands, and provides a safeguard against other wireless transmitters, while offering fast system response and elimination of data collisions. Telegrams transmitted by the protocol are less than one millisecond in duration (a minimum for switch commands), and are transmitted at a data rate of 125 kb/s. The range of energy harvesting wireless sensors is about 300 meters in an open field and up to 30 meters inside buildings.
A major requirement of reliable and cost-efficient systems is interoperability between the products of different manufacturers, which is why M2M calls for standardized technologies. Interoperability of different end-products based on energy harvesting technology has been an important factor for the establishment of the technology on the market. For this reason, the EnOcean Alliance, a consortium of companies working to further develop and promote self-powered wireless monitoring and control systems for sustainable buildings, have formalized standardized application profiles (EnOcean Equipment Profiles, EEP 2.5) that allow for products from different manufacturers to communicate and work amongst themselves. EnOcean wireless devices can be connected to different communication standards such as BACnet, LON, TCP/IP, KNX, or DALI via gateways.
Smart Energy Management
Wireless energy harvesting is rapidly becoming the established standard for the last leg communication level in M2M applications, because it eliminates the need to pull wiring, is batteryless, and is maintenance-free. An example is the smart grid, which is becoming a major part of the energy supply network for today and tomorrow. It’s intended to network centralized and decentralized energy suppliers to an intelligent system that provides energy only when needed, updating in real-time. This requires continuous data flow and processing from all involved parties from millions of information points.
One key to this is a smart metering system. To work reliably and cost-efficiently, interoperability between the meters is supplied by different manufacturers. The members of the EnOcean Alliance have defined a specific device communication protocol: The Automated Meter Reading (AMR) profile for batteryless wireless devices. Smart meter systems based on this open protocol are available from a number of manufacturers, such as the meters from Eltako and the control system from BSC. The Eltako components read and transmit the current electricity, water, and gas consumption, including accumulated meter figures, by means of energy harvesting wireless technology located at a variety of points inside a building. In addition, the software monitors and displays the current meter readings, and compares them against default values. This makes all relevant data available for systems processing it for intelligent energy management on demand.
Message from a Mouse
M2M systems including energy harvesting wireless technology can simplify company-relevant workflows and processes in a variety of ways. M2M communication can help make pest control in the food industry more efficient. No business in this industry can afford a mouse infestation. National and international hygiene standards do not permit poison traps, therefore permanent systems to monitor the inflow of rodents need to be equipped with snap or live traps. These have to be checked regularly – depending on the size of the company, this can be time-consuming.
The eMitter traps from BioTec-Klute and BSC offer a sophisticated and cost-efficient alternative. The traps are equipped with EnOcean energy harvesting wireless technology. When a mouse enters the trap, it activates a switch and triggers an EnOcean radio signal. A GSM controller receives this message and informs an inspector via mobile communication, either by text message or e-mail. The animal can then be removed from the trap. This round-the-clock monitoring shortens the process. The key to this solution is the integration of EnOcean wireless technology and mobile communications. EnOcean radio signals are able to cover the short distance to the next controller. The GSM transmission technology is then used for the next stage of communication – from the controller to the cell phone or PC of the employee.
Other M2M applications for energy harvesting wireless technology include monitoring maritime shipment containers or cold chain systems in supermarkets. In all these scenarios, wired systems would be too elaborate in their technology and by no means cost-effective. Energy harvesting wireless technology is consequently set to play an increasingly important role in realizing deeply interconnected M2M systems more reliably, more conveniently, more economically, and utilizing existing communication technologies.