Energy all around us can power smart home controls
The explosive growth of wireless devices that control and automate lighting, heating, security and other services in homes and offices is bringing an equally explosive growth in demand for batteries – just at the point when we’re all becoming aware of the need to control and recycle waste products. Fortunately, there is an alternative source of power for wireless switches and other controls: using the energy of motion to generate tiny amounts of energy. This can be more than sufficient to drive a control circuit.
Whether it’s lighting control, security, AV or entertainment hubs, batteries enable the controller to be situated anywhere and can be moved from room to room, no longer limited by wiring and the placement of power outlets. Yet they always seem to run out of juice at the most inconvenient moment. For home and consumer users there is the additional inconvenience of identifying and sourcing the correct replacement. Larger installations such as multi-occupancy buildings face the further headache of scheduling and managing the process.
These may seem like minor issues in the home, but there is a much bigger picture.
With the explosive growth of the Internet of Things (IoT) there are billions of wireless devices that need independent power, as well as constant operation. Whether in smart buildings or industrial networks, it is a massive challenge to monitor every battery and manage their replacement. Financial cost and inconvenience are not the only issues.
A key concern is the environmental impact. Batteries are a drain on natural resources such as lithium. It is estimated that if 10 trillion wireless sensors will be needed to send and receive data around the IoT, this will require 1 million tons of lithium. That equates to the combined worldwide lithium production of 10 years. Add to that the demand for batteries in smart phones, electric vehicles, energy storage systems and the like, and it becomes clear that there is not enough lithium in the world for all possible applications. Moreover, the environmental impact of lithium mining results in water shortage, air pollution and destruction of nature reserves. And no recycling process has yet been invented that could produce enough pure lithium second use in batteries.
Then there is the issue of disposal. As well as lithium, other battery technologies also use toxic heavy metals such as mercury, lead, cadmium, and nickel, which are detrimental to the environment as well as scarce and difficult to recycle. It takes six to ten times more energy to reclaim metals from some recycled batteries than from mining. (source: Battery University).
The way forward – energy harvesting
If batteries can’t supply the needs of switching, control and communication in the home and IoT – what are the alternatives? One option is to supply power by wires, however this is costly and causes disruption to the buildings’ tenants. Additionally, wired systems can’t be expanded easily when demands change. A better option is to harvest energy directly as the device is used.
Today’s energy harvesting wireless devices generate all energy required for their operation from their environment. The most obvious example is the energy harvesting wireless switch that generates its energy from the kinetic movement of being pressed. Conveniently, sensors can also be self-powered, harvesting the small amounts of power required from ambient light (indoor and outdoor) or temperature differences.
Energy from motion
Kinetic energy harvesting uses the power of motion to generate energy for wireless signals. When pressing a switch, for example, an electro-mechanical energy converter is activated and uses this movement to generate energy for a telegram. This telegram can turn on/off household appliances, a light or create different scenes for LED lights. The same functionality can be used for a kinetic window contact, which registers if a window is open or closed, or a self-powered water sensor. Here, the energy converter is activated when water gets in touch with the swelling material on the sensor’s bottom. The sensor, positioned below the bathtub or the washing machine, can now send a wireless signal to prevent water damage.
"If batteries can’t supply the needs of switching, control and communication in the home and IoT – what are the alternatives?"
The kinetic principle is embodied in energy harvesting switches like those by EnOcean, which employ a miniature generator inside an apparently conventional light switch. Based on a miniature magnet and coil generator, the action is quiet and smooth – nothing like the piezoelectric spark on a kitchen hob or barbeque. When the switch is pressed just 1.8mm (like a standard wired switch) the generator produces all the energy required to send a control message to the lighting receiver via a low-energy radio. Pressing and holding the button enables the switch to send another telegram, for example to brighten, dim or change the lighting colour. This remote switch will never have a dead battery.
As well as the practical advantages that zero battery replacement brings, consumers benefit from familiar switches and controls, from a simple on-off switch to up-down touch switches, and sliders or dials for controlling light intensity or colour. The same interfaces can be applied to heating and home entertainment systems, making it much easier than using an app on smartphones or tablets and anyone in the house can use them.
Putting it together
Based on the ultra low-power EnOcean wireless communication standard (ISO/IEC 14543-3-1X) in sub-1-GHz, there is a large interoperable ecosystem of products available for self-powered solutions. There are also self-powered devices integrating EnOcean’s energy harvesting technology which can communicate directly with the lights via Bluetooth or Zigbee enabling green, battery-free switches to be used to flexibly control additional applications such as LED lights or loudspeakers.
Among the best-known smart home automation standards, Philips Hue has become synonymous with smart lighting, bringing colour-changing lamps, dimming capability and intelligent app control to the domestic market. There is no need to change the wiring and the lights are ready to be used straightaway.
"By significantly reducing batteries, it might just help to make smart homes a little bit 'greener'."
All that is needed is a Philips Hue Bridge and at least one bulb. The most recent bridge is compatible with home hubs including Apple HomeKit, empowering users to set up their iOS Device to configure, communicate with, and control smart-home appliances as well as lighting. More convenient and time saving than using mobile devices to control the home, the Philips Hue Tap is a self-powered wireless switch, which provides the ideal flexible, maintenance-free control via Zigbee for Philips Hue lighting systems in LED consumer lighting. As part of the Philips Friends of Hue programme, several lighting control manufacturers have now launched various switch designs based on the energy harvesting technology from EnOcean. Available in a variety of colours and styles, the Friends of Hue Switches thus blend seamlessly into any home environment. The battery-free wireless switches offer the same look-and-feel as other light switches in the home and can be extended beyond lighting up to complete smart home applications.
Examples to us all
Vimar Friends of Hue wireless self-powered switches for example offer optimal customisation of shapes, materials and colours, the radio frequency controls integrate seamlessly with any living environment. The switches are suitable for renovations, redevelopments and furnishing updates, or any installations that have regulatory or architectural constraints. Wireless modular controls can be installed on standard flush mounting boxes or can be placed almost anywhere, on glass or wood surfaces, using double-sided tape. They ensure maximum installation flexibility, since there is no need for masonry work or having to repaint walls, and switches can therefore be whenever necessary.
Another market player, Senic, has recently introduced a battery-free switch called Nuimo Click. Nuimo Click allows users to turn their Philips Hue lights on and off, dim them or select light scenes. In addition, Sonos loudspeakers can also be controlled with just one click using the battery-free switch based on EnOcean energy harvesting technology. The Nuimo Click together with the Nuimo Hub creates an open platform based on the EnOcean wireless standard that can be continually updated with new integrations. With no need for additional coding, wiring or integration, Senic invites switch manufacturers who incorporate EnOcean modules for their self-powered double-rocker switches to control Sonos system out of the box via the Nuimo Hub.
Home automation systems like these fulfil the aim of creating increasingly connected buildings that allow people to live in the smartest possible way, marking a further stage of technological and stylistic innovation. This is just the start, as battery-free technology extends its benefits beyond the switches in the home right out across the global Internet of Things. By significantly reducing batteries, it might just help to make smart homes a little bit “greener”.
Jürgen Baryla is the vice president of sales for EnOcean GmbH.