In 2013, the primary energy consumption of the industrial sector was one per cent lower than the year before. Nevertheless, it still accounts for 43.6 million tons of oil equivalent. No question, there is a need for more efficient use of energy in industrial facilities. Newly constructed plants typically incorporate energy efficient buildings and equipment. However, existing facilities are often less efficient and face greater retrofit challenges.
These retrofit projects call for innovative, sustainable technologies that can be easily installed at relatively low cost. Automation systems monitor, control and conserve energy, delivering savings between 20% and 30%.
From building automation to energy management
The intelligent control of energy requires sensors to collect the relevant data from several points of measurement and receivers to process the information. A larger system can comprise hundreds to thousands of these sensing devices requiring power and communication.
There are already established technologies, primarily in the field of building automation, which can be a driver for intelligent energy management. In a building automation system, for example, thousands of sensors measure data from many different points, recording data on temperature, CO2, light or room occupancy to enable a central controller to optimise the building environment and meet individual requirements. It is not much of a stretch to go from building automation to an energy management system. Therefore, building automation principles can be the basis for energy automation processes in industries.
A major challenge is how to network an increasingly large number of individual wireless nodes or sensors that can communicate with long-range wireless networks. Different wireless standards can be used for this purpose, for example GSM, Bluetooth or IP. These standards support applications where large volumes of data must be transmitted quickly, for example in smart metering systems. However, high data rate comes at the price of high energy demand at the remote node, requiring a continuous supply of power either over cables or via large capacity batteries.
Network of sensors
For smaller devices, such as sensors for data collection, these technologies are suitable up to a point. This is particularly true when measured data from many different points must be available to an intelligent controller. Here, however, power cables or batteries can prove to be a drawback in complex applications. Batteries last for only a limited time, depending upon the application, and must be replaced regularly and disposed of properly. In such a highly connected energy control system, demanded in industrial plants, this can be costly and lead to downtimes.
Downtimes are out of the question in the industrial field where the success of a business include production up-time and process machinery efficiency. Energy harvesting wireless technology can overcome these problems, connecting a large number of batteryless and maintenance-free sensors into existing Wi-Fi or mobile networks that process data for intelligent energy control.
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, miniaturised energy converters generate power for the wireless communication of devices, keeping the maintenance effort to a minimum enabling a highly flexible installation.
For optimal indoor RF effectiveness, the EnOcean radio protocol uses sub 1 GHz frequency bands and also offers fast system response and elimination of data collisions. In addition, sub-GHz radio can have twice the range of 2.4 GHz signals for the same energy budget with better material penetration in buildings. As a reference, an equivalent energy harvesting wireless system at 2.4 GHz system requires about four times more receiver nodes to cover the same area increasing its cost versus a sub-GHz solution. RF reliability is assured because wireless signals are less than one millisecond in duration and are transmitted multiple times for redundancy. The range of energy harvesting wireless sensors can be about 300m in open air and up to 30m inside buildings.
A major requirement of reliable and cost-efficient systems is the interoperability between the products of different manufacturers – which is why smart energy control calls for standardised technologies. Interoperability of different end-products based on energy harvesting technology has been an important success factor for the technology’s strength in the market today. 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 formalised standardised application profiles (EnOcean Equipment Profiles, EEP 2.5), based on the international wireless standard ISO/IEC 14543-3-10, which is optimised for ultra-low power and energy harvesting applications. The profiles allow products from different manufacturers to communicate and work amongst themselves.
These standardised energy harvesting wireless devices can be easily integrated with other communications protocols such as Ethernet/IP, KNX, BACnet or LON via gateway controllers incorporating the technology into energy management programs. IPv6 network connectivity, for example, can easily be achieved by a number of gateway controllers from members of the EnOcean Alliance. They also have the option to secure network communication via industry-standard AES-128 encryption.
This enables plant operators to plan a widely distributed automation system that combines the added value of easy installation, reliability and lowest maintenance effort giving better user acceptance for the required energy control measures. Due to this integrated system approach, sensors measure energy consumption and automatically communicate to a server and website visualising status and trends. The user instructs the system over a web portal, for instance, to adapt set point data to an optimal level. In addition, batteryless wireless sensors can measure data which, together with the current production volumes, can be used by the automation system to calculate the required energy.
Energy management is not only about monitoring but also decision-making. The more data that is inputted via sensors, the better the insight into the system status. Decisions on controlling machines for an optimised use of energy can be made faster and closer in accordance with the actual production process. Unlike the standard approach where one or more sensors are connected to one central control unit acting in isolation, wireless networks allow diverse systems such as lighting, HVAC and process controls to give more global control.
Last level of energy control
Wireless and batteryless technology facilitates energy monitoring and control with little impact into the existing infrastructure. The wireless devices are highly flexible to install so that individual components can be easily networked to form a deeply connected system without complex cabling, especially in retrofit projects. Due to these characteristics, standardised batteryless technology is ideally suited for the last communication level in energy management applications, providing the needed data from each measurement point optimising control and enabling a comfortable user experience.
By John Corbett, sales director UK, EnOcean