SUCCESSFUL IMPLEMENTATION OF ENERGY HARVESTING IN VARIOUS FIELDS
3.1 KINETIC ENERGY
Piezoelectric transducers create electricity when subjected to kinetic energy from vibrations, movements, and sounds. The transducer changes the kinetic energy from vibrations into an AC output voltage which is then corrected, regulated, and stored in a thin film battery or a supercapacitor.
Some practical examples are:
• A remote control unit without battery: Energy in terms of power is harvested from the force that one uses in pressing the button. The energy that is harvested is enough to power the low-power circuit and transmits the infrared or wireless radio signal.
• Pressure sensor car tires: Piezoelectric energy harvesting sensors are put inside the car tire where they monitor pressure and convey the information to the dashboard for the driver to understand.
• Piezoelectric floor tiles: Kinetic energy generated while the people walking on the floor is transformed to electrical power that can be used for vital services such as display systems, emergency lighting, powering ticket gates, and more.
3.2 RF ENERGY HARVEST
RF energy signal is collected from an RF power receiving antenna and feeds it to an RF transducer. These types of sensors are used in building automation, smart grid, defense applications, industrial monitoring, and more.
3.3 PHOTOVOLTAIC (PV) ENERGY HARVESTING
Small solar cells utilize a small photovoltaic cell which converts light into electrical energy and is used in industrial and consumer applications such as satellites, portable power supplies, street lights, toys, calculators, and more.
Photovoltaic (PV) energy harvesting which is a wireless technology hence it provides significant advantages over the wired or solely battery-powered sensor solutions. These are virtually inexhaustible sources of power with little or no adverse environmental effects. Recently, PV technologies have come to the forefront in Energy Harvesting such as Dye-Sensitized Solar Cells (DSSC). The dye absorbs light similar to chlorophyll does in
plants. Electrons released on impact escape to the layer of TiO2 and from there diffuse, through the electrolyte, as the dye can be tuned to the visible spectrum and much higher power can be produced.
3.4 THERMAL ENERGY HARVEST
Thermoelectric energy harvesters rely on the Seebeck effect in which voltage is produced by the temperature difference at the junction of two dissimilar conductors or semiconductors. The sources include water heaters, an engine, the back of a solar panel, the space between a power component such as a transistor and its heat sink, etc. Applications include powering wireless sensor nodes in industrial heating systems and other high-temperature environments.
3.5 FLUID FLOW
Airflow can be harvested by a various turbine and non-turbine generator technologies. For instance, Windbeam micro generator captures energy from airflow to recharge batteries and power electronic devices. The generator consists of a lightweight beam suspended by long-lasting springs within an outer frame. The beam oscillates rapidly when exposed to airflow due to the effects of multiple fluid flow phenomena. A linear alternator assembly transforms the fluctuating beam motion into electrical energy for effective use. A lack of bearings and gears eliminates frictional inefficiencies and noise. The generator can operate in low-light environments unsuitable for solar panels (e.g. HVAC ducts) and is less costly due to low-cost components and simple construction. The technology can be optimized to satisfy the energy requirements and design constraints of a given application.
The flow of blood can also be used to power devices. For instance, the pacemaker developed at the University of Bern, uses blood flow to wind up a spring which in turn drives an electrical micro-generator.
3.6 SMART TRANSPORTATION INTELLIGENT SYSTEM
A smart-road technology uses piezoelectric sensors that can be used to create systems that are intelligent and improve productivity in the long run. Applications include highways that alert motorists of traffic jam before it forms, or bridges that report of danger when they are at risk of collapse, or an electric grid that fixes itself when blackouts hit. For many decades, scientists and experts have argued that the best way to fight congestion is to have an intelligent transportation system, such as roadside sensors to measure traffic and synchronized traffic lights to control the flow of vehicles. But the spread of these technologies has been limited by cost. Most of the technologies are still at the development stage and might not be practically available for five years or more.
3.7 BLOOD SUGAR OXIDATION
Energy harvesting can also be done through the oxidation of blood sugars. These energy harvesters are called bio batteries. These batteries could be used to power implanted electronic devices (e.g., pacemakers, implanted biosensors for diabetics, implanted active RFID devices, etc.). Recently, the Minteer Group of Saint Louis University has created enzymes that could be used to generate power from blood sugars. However, the drawback is that the enzymes would still need to be replaced after a few years.
3.8 ELECTRIC PAVEMENT
A company called PaveGen has produced pavement slabs that produce electricity; in addition to permanent installations. This has been demonstrated at various events such as the 2012 London Olympics and the Paris Marathon.
Figure 3: Electric Pavement
3.9 PEDAL POWER
Pedal power is simple, efficient, and practical which are essentially of two designs namely, the reciprocating treadle and the rotating pedal crankset. Pedal Power is the most familiar as used for bicycles or tricycles, popular for light transport since the late 19th Century. The beach-side Quadra cycle which was patented in the year 1853 and demonstrated that power could be drawn from more than one cyclist.
3.10 ATMOSPHERIC PRESSURE CHANGES
The change in air pressure due to temperature changes or weather patterns has been used to provide power for mechanical clocks such as the Atmos clock.
3.11 ENERGY TREE
Scientists at VTT research center in Finland have developed an “Energy tree” which that harvests solar energy from its environments whether indoor or outdoor that stores and turns it into electricity to power small devices such as mobile phones, humidifiers, thermometers and LED light bulbs. The technology can also be used to harvest kinetic energy from the environment. The “leaves” of the tree are flexible, patterned solar panels made using a printing process technique that was developed by VTT. The leaves form an electronic system complete with wiring that conducts energy into a converter that feeds electricity to devices such as mobile phones or sensors analyzing the environment.
The research center also developed 3D technology based tree trunk by exploiting wood-based biomaterials. These technologies create endless opportunities for applications involving different kinds of electronics regarding lighting and energy harvesting, for example. The tree having more solar panels can harvest more energy.
Figure 4: Energy Tree
3.12 SMART PARKING AND ENVIRONMENT MONITORING
Smart Parking & Environment Monitoring System that has been developed by several companies and institutions including Telefonica and the University of Cantabria. This project aims at designing, deploying and validating in Santander and its environment that a platform composed of sensors, actuators, cameras and screens to offer useful information to citizens. It has been installed to monitor different parameters such as noise, temperature, luminosity and CO. Libelium, which is a wireless sensor network platform provider for Smart Cities solutions, uses Waspmote‚ Plug & Sense Platform that are solar powered to allow energy harvesting and years of autonomy.
3.13 WALKING CHARGER
A personal electronics mobile power source has been commercialized by various energy harvesters called the Walking Charger. The Walking Charger allows users to charge the batteries in their mobile electronics devices anytime, anywhere – just by walking. Smartphone battery can be charged effectively by walking for just a single hour wearing that Walking Charger device.
Nowadays, people depend on their portable electronic devices for information, entertainment, and guidance and sometimes for survival. In those circumstances, running out of battery power is not an acceptable option hence the energy harvesters have created the walking charger to give people the ability to charge mobile electronics batteries anytime, anywhere.
3.14 ZEBRANET & TURTLENET
ZebraNet is a mobile sensor network with sparse network coverage and high-energy GPS sensors to track zebra movement. Continuous locating using GPS technology is done to track the long-term animal migration patterns, habitats and group sizes.
TurtleNet is a project with the goal of addressing the sensing and communication challenges related to the in-situ tracking of turtles. This is an effort similar to the ZebraNet project and extends on ZebraNet’s contribution of powering portable sensors using solar cells, to do perpetual wildlife.
SHiMmer is a wireless platform for sensing and actuation for structural health monitoring. Like Everlast, SHiMmer is a solar energy harvesting system that uses supercapacitor as storage. SHiMmer uses a technique of localized computation, known as active networking, in which the node actuates the structure, senses the vibration and then locally performs computations to detect and localize the damage.
Solepower is an energy harvesting device that attaches to the shoe and harvests energy for the mobile device. EnSole is inserted into a shoe and is water resistant and made to work in any kind of environment. When the heel strikes the sole, it generates the power and sends it to the PowerPac connection which is outside of the shoe. There is a fabric holster that mounts the PowerPac and it is this device that the USB charging can take place to the mobile device.
Figure 5: SolePower
3.17 ELECTROMAGNETIC ENERGY HARVESTING
Electromagnetic-energy harvesting is a system that converts mechanical energy produced by vibration to electrical energy, which in turn powers wireless sensor nodes. These sensor devices are used to monitor valuable equipment and assets across a wide variety of industries, including: Rail; Oil and gas; Chemicals; Power generation; Water & Wastewater treatment; and Process manufacturing.
3.18 MINIATURIZED ENERGY CONVERTERS
EnOcean manufactures maintenance-free wireless sensor solutions for use in buildings, industrial installations and smart home and consumer applications. These are based on ultra-low power electronic circuitry, miniaturized energy converters, and reliable wireless communication.
GreenTEG works with thermoelectric technology developed at the Swiss Federal Institute of Technology (ETH Zurich) that generates electricity from any thermal source where one side of the Thermoelectric Generator (TEG) is warmer, or colder than the other. Possible uses include: Building Technology (e.g. an Automated Heating Valve); Consumer Electronics; Industry; and Research.
Figure 6 : GreenTEG
3.20 VIBRATION INDUCED BROADBAND EXCITATION
MicroGen Systems, Inc. is a company that develops solutions for wireless and mobile electronic devices. They develop micro-sensors and micro-power products. These two products have been developed using single frequency Bolt micro-power generator and the VIBE generator which stands for Vibration Induced Broadband Excitation. VIBE is able to generate energy through vibrations.
MARKET TRENDS & FUTURE POSSIBILITIES WITH ENERGY HARVESTING
The future market possibilities of energy harvesting include:
• Construction sector especially building and infrastructure, lighting sector that is automated, security systems, and electronics at homes.
• The use of mmWave (millimeter wave) for 5G cellular networks has been a popular trend of wireless energy harvesting.
• Growing application of energy harvesting in wearable devices and mobile phones would expect a market pull.
• In the near future, Energy harvesting is projected to find increasing applications in the automobile industry.
• Nanotechnology has offered ample of growth opportunities to the energy harvesting market since this helps to manufacture compact-sized devices. Most importantly, portable devices based on energy harvesting technology are the most likely occur in the market.
The energy harvesting market is segmented into North America, Latin America, Asia Pacific, Japan, Western Europe, Eastern Europe, and the Middle East and Africa. Among these, Americas are projected to remain the dominating markets in 2017, with a significant market share. However, next to America, Europe will be the fastest growing market, owing to growth promotion and investments by The European Commission in R of energy harvesting and storage devices. North America and Asia Pacific will also account for outstanding market shares by 2020 end. In North America, the U.S. will dominate, whereas, in APAC, Japan will reportedly contribute the largest share to the total energy harvesting market revenues.
ADVANCES IN ENERGY HARVESTING
The next generation of radio technology will enable up to ten times longer radio ranges for wireless transmissions of more than three kilometers for outdoor applications with high range requirements. The increased energy demands for such long distances will need to be met through the progression of energy harvesting technology and the associated building blocks. Lowering device energy consumption is an important adjustment for improved performance, especially for critical functions such as the sleep and receiver current of sensor nodes. Tests have already shown that a 10x reduction in timer currents is technically achievable for the next generation of sensor modules. Developments are also being made that will improve the efficiency of motion, light, and temperature-based energy harvesting technology in the coming years, with research revealing the efficacy of new designs and innovative deployment models:
• Motion – New types of mechanical energy harvesters using rotational motion, for example, can make use of energy of flowing gases and liquids.
• Light – Light will remain one of the most frequently used energy sources, as next-generation products will combine higher efficiency solar cells with improved performance under low light conditions. While today’s limit of operation is light intensities of about 100 lux at 5 percent efficiency, tomorrow’s solar cells based on organic material or dye-sensitized technology will operate down to 10 lux light intensity with more than 10 percent efficiency.
• Temperature – Harvesting temperature differentials is only beginning, with one new option being to harvest day and nighttime temperature differences in outdoor applications. These harvesters, which already work in the laboratory, will enable very robust sensor nodes that operate independently of light and are not sensitive to dirt. For example, they may be deployed underground, which is often the case in industrial environments.
Besides the energy need, research is also evaluating improved storage components. The target is to store harvested energy for several months without new ambient energy impulses being required. This could enable battery-less sensors that can “sleep” for much longer periods of time, retaining energy stores until an incident wakes them to measure and send signals. This is particularly interesting for alarm systems in dark environments, for example in a forest or other poorly illuminated areas.
Energy harvesting (EH) is becoming increasingly viable as a power source for small electronic devices. Because of their remote location and due to their small size and large count, it may become impractical or even impossible to connect such devices to the power grid or to supply them with batteries. Hence, an included small power source can drastically simplify the device installation and reduce its maintenance costs.
Energy harvesting is a very common and widely acceptable technology for a long time. But when it comes to support the most promising and upcoming technology, WSN (Wireless Sensor Networks), it makes a lots of difference in its design installation deployment and maintenance. Energy harvesting for low-power embedded devices like wireless sensors presents a new challenge as the energy harvesting device as it has to be small enough with the sensors.
Furthermore, the ability to harvest energy from the environment is highly dependent on many environmental factors and these need further research to understand and exploit. This report only provides a brief description of the possibility, opportunity, current trends and application of various energy harvesting methods and applications.