Energy harvesting is the conversion of ambient energy into electricity to drive small or mobile electronic and electrical devices. Wireless sensors are particularly in need of energy harvesting because they are increasingly deployed in numbers and locations where hard wiring or battery changing are impracticable. We are at an exciting stage with both because harvesting is becoming better and electronics is demanding less power -so they meet in the middle.
The sectors that are at the tipping point in adopting these technologies are Aerospace & Military, Industrial, Automotive & Urban, Buildings, Health care and Logistics. For example, Boeing, NASA, United Technologies, Rockwell Collins and Microstrain have trials and rollouts of a rich variety of wireless sensors rendered more reliable and long lived by energy harvesting. They variously harvest heat, vibration, strain, solar and other ambient energy, increasingly employing several modes in one device to reduce or eliminate battery use.
In industrial applications, leaders in wireless sensors such as GE and Emerson are moving on to true meshed networks where Dust Networks manages with remarkably low power. This is very significant because the incorporation of energy harvesting is easier. Active RFID leader Identec Solutions has moved into real time location and wireless sensing and PMG Perpetuum's electrodynamic wide band vibration harvesting is now successful in industrial sensing applications
Automotive and urban
Automotive and urban uses of harvesting are now very varied and a rapidly growing market. Regenerative braking in cars and that solar panel on the roof are now yesterday's story and next comes Levant Power Systems adding energy harvesting shock absorbers. BBN Technologies is developing an urban scale wireless network and Novotech has roadway power systems based on harvesting. Most are based on harvesting movement but Automotive Thermoelectric generators on engine and exhaust are nearing market readiness.
Buildings now widely employ wireless controls and sensors that use batteries. Many have moved on to use energy harvesting, sometimes without any batteries. Indeed, more than 100,000 buildings in the world now have wireless sensors and actuators with energy harvesting and no batteries. Power from light, heat and movement are favorites here but the $20 billion Schneider Electric of France and others have demonstrated how thermoelectrics has a place too. In addition, Powerleap has self-powered smart flooring solutions. However, although China is installing 485 million smart meters, most will have hard wired communication for now.
Health care is a sector where there is not yet a lot to see in terms of wireless sensing let alone using energy harvesting. Yet a few percent of people die when cut open to change their heart defibrillator or pacemaker electronics. Finding a better way can be a matter of life and death in other procedures as well. Tagsense now has a diagnostic skin patch. Biorasis has a continuous glucose monitoring device. Massachusetts Institute of Technology is developing embedded and wearable sensor networks for sports medicine, smart utilities and interactive media such as human-computer interfaces that will help the disabled. GeorgiaTech is developing self powered implantable nano devices. There is a tsunami wave of eagerly expected inventions about to hit the health care sector. The more enthusiastic may even say, "Superwoman here we come."
In logistics, the leader in using active RFID with sensors on military supplies and equipment and in heavy civilian logistics is the Lockheed Martin Company Savi which now envisages tracking just about everything wirelessly. Indeed, Omnisense has developed seamless geolocation in a wireless sensor network.
Seeking Large Wireless Sensor Networks
Large wireless sensor networks are needed on trees to monitor forest fires and for holistic management of oil refineries, undersea prospecting and extraction, pollution outages and much more besides. Consequently, coping with more wireless sensor nodes and making them maintenance free for 20 years is concentrating the mind as well as getting longer range. Contributions here come from BIMAQ on large sensor networks, the work at Princeton University on low cost piezoelectric ribbons. Add Northeastern University progressing capacitive energy storage with much longer life than that of a rechargeable battery, Teledyne Benthos doing energy harvesting on the sea floor and Voltree Power creating electricity from living trees.
Allied Technologies Have a Place
There has been mixed success with beaming electric power to vehicles and devices, from the useful cordless toothbrush to the unsuccessful coils in the road to power electric vehicles. There is more to come with these technologies and they are part of the equation even if not quite within our definition of energy harvesting. Watch Leggatt & Platt, Proxima RF and Powercast. Widetronix is manufacturing small millimeter-sized, beta emission "batteries" with more than 25 years life for nanowatt to milliwatt applications in defense, medical, and logistics sectors, totaling $4 billion in addressable market, it estimates.
Many of these new markets are already substantial. The only available report analyzing the whole energy harvesting market, the IDTechEx, "Energy Harvesting 2010-2020" forecasts a market of over US$2 billion dollars in 2016 just for the harvesting elements, excluding power storage and electronic interfaces. We see nearly 10 billion energy harvesting devices being sold in 2020. Energy harvesting on wireless sensors is only a modest part of this number but their sophistication will often justify premium pricing. IDTechEx forecasts the market for Wireless Sensor Networks (truly meshed ones) in its report "Wireless Sensor Networks 2010-2020." WSN is otherwise known as Third Generation Active RFID. This report includes WSN with and without harvesting and it shows a market of over $2.7 billion in 2020, that being larger than that for Real Time Locating Systems RTLS at that time. RTLS is Second Generation Active RFID. For more see the IDTechEx report "Real Time Locating Systems 2010-2020."