Batteries are part of our daily life. Increasing mobility means increasing numbers of devices powered by batteries. Battery capacity is improving, but there are limits and hazards associated with this proliferation.
Battery technology is pushing the limits of current chemistry. The troublesome fact remains: batteries contain heavy metals such as mercury, lead, cadmium, and nickel, which are detrimental to the environment. At the end of their lifetime, batteries remain hazardous waste and need to be carefully (and expensively) disposed of by the manufacturer or the user.
One recommendation by the US Environmental Protection Agency (EPA) to reduce the number of batteries in the waste stream is to use rechargeable batteries. This is reasonable, but it's almost always limited to devices that don't need to function 24/7. In Internet of Things (IoT) networks, where small devices like sensors and relay receivers collect and process data for an intelligent control, reliability, and continuous operation are critical in keeping the system functional. The fact is, more malfunctions are caused by battery failures than by electronics, especially in large systems.
These days, governments set ambitious goals to slow down climate change, support the use of renewable energies, and find new ways to reduce waste and carbon emissions. In the words of President Obama, "...to put us, and the world, on a sustainable long-term trajectory." So isn't this the ideal time to think about alternatives to batteries?
This brings the energy harvesting principle to the forefront, not just as a future option but as a relevant solution today. Over the past 10 years, energy harvesting wireless technology has made significant leaps enabling wireless modules to gain their power from the surrounding environment.
For example, tiny electro-dynamic energy converters use mechanical motion or a miniaturized solar module generates energy from light. Combining a Peltier element with a DC-to-DC ultra-low-voltage converter taps temperature differences as an energy source. Even minute amounts of harvested energy are sufficient to transmit a wireless signal. Adding a capacitor can ensure adequate power storage to bridge intervals when no energy can be harvested.
The energy harvesting technology enables batteryless automation devices and systems, such as a building's efficient energy control, based on resource-saving technologies that eliminate the need for batteries. Such automation systems can save up to 40 percent of energy use. The energy harvesting principle is a unique aspect that ensures the sustainability of all system components, bringing the cleantech idea to each single device.
When deciding on wireless technologies, design engineers aren't solely interested in the cleantech character of energy harvesting wireless devices. A demand for battery-powered devices is that batteries must be easily removable from consumer products to make it easier to recover them for recycling. This restriction to product designs doesn't apply to energy harvesting-powered devices, enabling a more flexible, functionality oriented design.
Based on energy-harvesting wireless technology, a wide range of energy-autonomous applications are available today. Including batteryless switches, intelligent window handles, temperature, moisture, and light sensors, as well as presence sensors, relay receivers, heating valves, control centers, and smart home systems. In contrast to battery technology, energy harvesting has considerable potential both to improve the efficiency of the current three energy sources and to develop new ones.
Batteries will never disappear, and for some applications they'll remain a necessity. But from a design, environmental, and reliability standpoint, energy harvesting is the technology with a future. With sensor networks growing to the Internet of Things, where billions of small devices get connected, this will become even truer.
Jim O'Callaghan is the president of EnOcean Inc.