M2M communication enables equipment to interact with other equipment, typically without human intervention. This results in an intelligent network automatically managing everyday tasks in production, logistics, monitoring or smart buildings. The next step in M2M is the so called “Internet of Things” (IoT). There, it is conceivable that each and every end node—in other words, every sensor and device—will be connected to other devices and to the Internet. This includes devices which monitor the environment and report information as well as intelligent equipment which makes decisions locally and can interact with control solutions that communicate remotely, often over the Internet. With the help of open software platforms and secure data connections, every device could be controlled via mobile devices or the cloud. 

But the realization of IoT requires highly flexible technologies and portable devices that can be applied wherever needed. There are already well established protocols to share information over the Internet, TCP/IP, but this is primarily a computer to computer based protocol with sophisticated provisions. The requirements and capabilities for the remote nodes are often different and cannot support complex TCP/IP communication. But there are straightforward ways to bridge energy efficient wireless devices to TCP/IP, typically performed by gateways to BAS (building automation systems) or IP.

Deploying the millions of distributed devices introduces the challenge of: how should they be powered and how will they communicate. One of these ways to the success of the IoT is energy harvesting wireless technology. Wireless sensors and relay receivers enable simple deployment of intelligent nodes, however, wireless devices require power—historically this meant pulling a lot of wires or installing and replacing batteries. Devices powered by energy harvesters are maintenance-free and independent of batteries or other external energy sources, paving the way to a simpler installation of millions of devices connected to each other and the Internet. 

The Specifics of Energy Harvesting Wireless 

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 ever-present 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 wirelessly communicating devices. 

The devices are low energy, but not low power. They have been optimized to operate from small solar cells for example, with only indoor light, while storing enough energy to last over a weekend in darkness. For optimal RF effectiveness, the radio protocol uses 315 MHz and 902 MHz frequency bands in the US. The 902 MHz band in particular, offers the ideal characteristics for M2M applications and the future requirements of the IoT. Due to its efficient use of energy, the 902 MHz band achieves double the range of common 2.4 GHz devices for the same energy budget, which is 90 feet in buildings, for example. Simple and short wire antennas enable the integration of energy harvesting wireless technology into very small product enclosures. The result is an effective, robust wireless platform for applications in the building automation sector, for smart home solutions, health care products as well as consumer appliances or machine-to-machine communication. Standardized application profiles inform networked devices of the nature of the data, ensuring the interoperability of devices from different vendors. 

These features make energy harvesting wireless technology the ideal communication standard to easily and reliably interconnect thousands of individual devices in a system, as well as network them with other wireless protocols.

The Way to the IoT

Today, energy harvesting wireless technology is very well established providing M2M solutions in the building automation sector, bridging the control of light, HVAC and other fields of building technology to smart home, smart metering and energy management systems. This is the starting point to actuate further applications that lead to the IoT in the long term. The four following steps show what this could look like:

1. Monitoring and Control

Wireless and batteryless technology significantly eases energy monitoring and control in buildings with only little intervention into the existing systems. The wireless devices are highly flexible to install so that individual components, wall switches, sensors and relay receivers can be easily networked to form an intelligent system without complex cabling. In addition, dispensing with batteries eliminates the burdensome need to maintain the devices’ energy supply in a regular time period, which can be up to each year.

 

An example for such a flexible automation system is HVAC control. Here, a thermostat, VAV (variable air volume) or fan coil controller receives information related to occupancy, temperature, humidity, window position or CO2 from the respective batteryless sensors and controls the opening and closing of valve actuators for radiators, or dampers for VAV systems. At the same time, the controller sends status information to a central building automation system, and receives control messages from the BAS system. This enables the building to be monitored from a central location, that can be remote from the building itself, and to implement building wide settings, such as holiday shutdown, for example. Enormous progress is also being made on the product side, leveraging advancements in energy harvesting: Revolutionary self-powered radiator valves, from Kieback&Peter for instance, generate energy from the difference in temperature between the hot water and the surrounding air. This energy powers both the communication with a controller or BAS system, and to turn the valve itself. Without cables or batteries, these wireless devices are especially easy to install, and they require no maintenance.  

In further optimized systems, central equipment such as boilers or air handling units are integrated into the wireless communication system enabling scalable HVAC generation, visible and controllable over the Internet on a PC, tablet or smartphone. 

2. Performing Tasks 

Alarm systems are a second field, which batteryless wireless technology is opening up, due to its specific features. Here, the reliability requirements are a lot more stringent than those required for lighting controls. A system failure not only means a malfunction but can cause much more serious consequences for other systems that depend upon the equipment being monitored.  It’s a fact that more malfunctions are caused by battery failures than by the electronics, especially in large systems. Energy harvesting overcomes this issue. 

There are already various batteryless wireless water detectors, for example, from AFRISO using miniaturized solar cells or motion energy converters to power wireless signals that report water leaks in areas such as washing machines, under the bathtub (also in complete darkness), in the kitchen or in the bathroom. The wireless signal immediately sends the leakage information to a gateway controller or directly to a valve, causing that the main water pipeline or the affected supply line to be shut off. A notification is sent to the user’s smart phone or smart pad at the same time to inform them about the incident. In addition, the water valve can be opened and closed, independent of leakage notifications, by GSM connection via smartphone or smartpad. 

3. Embedded Processing

A major requirement of today’s and the future’s energy supply is the smart grid. It’s intended to network centralized and decentralized energy suppliers, including private homes producing electricity by photovoltaic installations, 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, which means from millions of information points. 

One key to this are smart metering systems. To work reliably and cost-efficiently, interoperability between the meters is supplied by different manufacturers – this is why smart metering calls for standardized technologies. Consequently, the members of the EnOcean Alliance have defined a specific device communication protocol, the AMR (automated meter reading) profile for batteryless wireless devices. Smart meter systems based on this open protocol are already available from a number of manufacturers, for example 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 BSC software monitors and displays the current meter readings, for example, and compares them against default values. This makes all relevant data available for systems processing it for intelligent energy management on demand.

4. Bridge to the Cloud

Via similar gateways, the standard-based energy harvesting technology can also communicate with Ethernet, Wi-Fi, GSM/UMTS/CDMA and other networks for integration in cloud services. Here, all data collected by batteryless wireless sensors is encrypted and transmitted to a cloud service over the Internet. The gateways connected to a control and visualization software by TCP/IP can be used to control all relay receivers and sensors bidirectional. Magnum Energy Solutions (MES) and BSC Software, for instance, have developed a cloud solution which offers energy management as-a-service. Therefore facility managers, building owners and businesses can monitor important inventory, equipment, assets and energy related information from anywhere at any time, via the cloud. Critical building related data is automatically pushed to the cloud, freeing owners and managers from the often-challenging coordination and expense of hosting onsite servers. 

One of the major advantages of such a cloud-based solution is that the management system arrives completely pre-commissioned from the manufacturer and ongoing device commissioning is expertly done on behalf of the client and pushed out from the cloud. The users are granted unlimited access to their remote, dedicated virtual server with their own IP address, accessible from a desktop or smart phone – the perfect precondition for a deeply connected world of an IoT.

As energy harvesting wireless technology advances, possibilities are emerging for using energy-autonomous, maintenance-free wireless modules for early warning systems or in domestic environments, adding extra functionality for more comfort and convenience, security and safety to existing systems. In agriculture, sensors could be placed over large areas to provide early warnings of forest fires, or to ensure that crops are receiving an optimal supply of water and nutrients. Batteryless technology is also suitable for monitoring built fabric such as large bridges. 

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 the IoT more reliably, more conveniently, more economically and utilizing existing communication technologies.