Now scientists at the Beijing Institute of Nanoenergy and Nanosystems and the Georgia Institute of Technology have developed a flat device that can harvest energy from both the sun and wind at the same time. Instead of relying on wind to spin a rotor, the device instead makes use of the triboelectric effect, the same effect behind everyday static electricity. When two different materials repeatedly touch and then separate, the surface of one material can steal electrons from the surface of the other, building up charge.
Solar and Wind Energy From the Same Device – IEEE Spectrum
The researchers coupled a triboelectric nanogenerator with silicon-based solar cells. The triboelectric nanogenerator consists of thin sheets of plastic and Teflon separated by air. When wind blows on the hybrid device, the plastic film vibrates toward and away from the Teflon, generating triboelectricity.
The device the researchers created is about 120 millimeters long and 22 mm wide, making it about as long and wide as a candy bar. However, at 4 mm deep, it is only about as thick as a windowpane. "The device could be extensively installed on the roofs of city buildings," says study co-author Ya Yang at the Beijing Institute of Nanoenergy and Nanosystems.
In experiments, the generator could deliver up to about 8 milliwatts of solar power and up to 26 mw of power from the wind. It could charge a lithium-ion battery from 0.2 to 2.1 volts in 10 minutes, and could also power the kind of temperature and humidity sensors one might find in a smart house, the researchers say.
Due to the rapid expansion of the Internet of Things (IoT), there is a heightened interest in developing low-power wireless sensors. Modern Internet of Things (IoT) systems incorporate wireless sensors to gather data in a trustworthy and useful way to monitor processes and manage operations in sectors like transportation, renewable energy, civil infrastructure, smart buildings manufacturing, environment condition monitoring, healthcare, defense, and manufacturing. When these IoT devices are designed and implemented, they must consider their long-term and selfsustaining activities from the outset. Multiple sources of energy can be considered for energy harvesting. These sources can be divided into five categories: organic, hybrid, mechanical, and human. Ambient energy sources are easily accessible and cost-free in the environment. These auditory sources can be categorized into various groups. Considered as some of the most recent are energy sources based on the solar energy, radio frequency, thermal energy, wind energy, and hydro-based energy sources. Furthermore, future research directions in the following areas can be considered as the most emerging.
Their electrolyzer extracts moisture from air and splits it via renewably powered electrolysis to create hydrogen. It is the first such electrolyzer to produce high purity (99 percent) hydrogen from air that has as little as 4 percent humidity, says Gang Kevin Li, a professor of chemical engineering at the University of Melbourne, in Australia. The success could open up the possibility of producing hydrogen in semi-arid regions, which also have some of the highest solar- and wind-power potential.
Many teams are working on alternative ways to make green hydrogen. Solar-powered water-splitting devices, for example, use photocatalysts, which absorb sunlight to split water into hydrogen and oxygen but have a low solar-to-hydrogen efficiency of only 1 percent. To overcome the need for freshwater, there have been attempts to produce hydrogen from saline and brackish waters, but the devices have to deal with contamination and chlorine as a by-product.
The researchers demonstrated the use of both solar panels or a small wind turbine to power the module. They tested the prototype both indoors and outdoors in the hot, dry Melbourne summer. The solar-to-hydrogen efficiency of the device is over 15 percent, Li says.
Besides danger, green H2 is a spectacularly dumb idea because to make it with solar or wind energy you can get only a 25-40% annual capacity factor. So if you build an H2 electrolyzer with capacity of 100,000 tons per year, you will get only 25,000 to 40,000 tpy; the plant will be idle or below capacity most of the time, unless you install excess solar/wind capacity and batteries. Not to mention the whole premise for switching to H2 is to stop climate change by reducing CO2 emissions - it is highly unlikely this would be effective. The good news is it also is highly unlikely that the more severe predicted climate disasters also are highly unlikely, so the whole H2 thing is a huge waste of time and resources.
To understand exactly what the problems are, and how they might be addressed, it's helpful to know a little something about how photovoltaic panels are made. While solar energy can be generated using a variety of technologies, the vast majority of solar cells today start as quartz, the most common form of silica (silicon dioxide), which is refined into elemental silicon. There's the first problem: The quartz is extracted from mines, putting the miners at risk of one of civilization's oldest occupational hazards, the lung disease silicosis.
After the publication of the Washington Post story, solar companies' stock prices fell. Investors feared the revelations would undermine an industry that relies so much on its green credentials. After all, that's what attracts most customers and draws public support for policies that foster the adoption of solar energy, such as the Residential Renewable Energy Tax Credit in the United States. Those who purchase residential solar systems can subtract 30 percent of the cost from their tax bills until the incentive expires in 2016.
Toxicity isn't the only concern. Making solar cells requires a lot of energy. Fortunately, because these cells generate electricity, they pay back the original investment of energy; most do so after just two years of operation, and some companies report payback times as short as six months. This energy payback" time is not the same as the time needed to recoup a consumers financial investment in solar panels; it measures investments and payback times in terms of kilowatt-hours, not in terms of money.
Of course, if you manufacture photovoltaic panels with low-carbon electricity (for example, in a solar-powered factory) and install them in a high-carbon-intensity country, the greenhouse-gas-payback time will be lower than the energy-payback time. So perhaps someday, powering photovoltaic-panel manufacturing with wind, solar, and geothermal energy will end concerns about the carbon footprint of photovoltaics.
Smart grid technology is enabling the effective management and distribution of renewable energy sources such as solar, wind, and hydrogen. The smart grid connects a variety of distributed energy resource assets to the power grid. By leveraging the Internet of Things (IoT) to collect data on the smart grid, utilities are able to quickly detect and resolve service issues through continuous self-assessments. Because utilities no longer have to depend on customers to report outages, this self-healing capability is vital component of the smart grid.
The increasing popularity of renewable energy resources presents a significant opportunity for transactive energy. Some renewable energy generation devices are residential generators based on solar and wind. These DERs require a flexible approach to energy transactions, and transactive control represents a potential solution.
In addition, solar and wind provide examples of renewable energy that depend on environmental conditions and are prone to fluctuations. As more people use them, the energy grid may also experience larger fluctuations in usage based on those same environmental conditions.
Given the value of some semiconductor materials, recycling and reclamation of valuable REE and other substances are options. At present, recycling REEs sees the most success when dealing with large-scale semiconductor products, such as solar cells, automobile catalysts, and wind turbine magnets. REEs are also reclaimed from batteries.
The situation is unlikely to get better anytime soon, for three reasons. First, as countries everywhere move to decarbonize, the electrification of transportation, heating, and other sectors will cause electricity demand to soar. Second, conventional coal and nuclear plants are being retired for economic and policy reasons, removing stable sources from the grid. And third, while wind and solar-photovoltaic systems are great for the climate and are the fastest-growing sources of electric generation, the variability of their output begets new challenges for balancing the grid.
Recognizing this similarity, we developed a technology called packetized energy management (PEM) to coordinate the energy usage of flexible devices. Coauthor Hines has a longstanding interest in power-system reliability and had been researching how transmission-line failures can lead to cascading outages and systemic blackouts. Meanwhile, Frolik, whose background is in communication systems, had been working on algorithms to dynamically coordinate data communications from wireless sensors in a way that used very little energy. Through a chance discussion, we realized our intersecting interests and began working to see how these algorithms might be applied to the problem of EV charging.
Power engineers that work on generation convert other forms of energy into electric power. These sources of power include fossil fuels such as coal and natural gas, hydropower, nuclear power, solar power, and wind power.
Conventional power systems consist of large power plants with synchronous generators (SG) which provide considerable inertia in the system. However, in recent years, the number of renewable energy sources like photovoltaic generation plants and wind farms that are connected via VSCs into the electrical grid has increased significantly. For instance, Doubly Fed Generators (DFIG) are widely employed in wind farms using VSC interface devices as they provide opportunity to work in different frequencies and different wind speed. Consequently, decoupling the actual inertia of the blades of wind turbines leads to the risk of frequency instability during the disturbance in the system. Hence, despite the fast response time of VSCs compared to the synchronous generators, the lack of any spinning component leads to lower frequency stability and consequently a lesser resilient grid. 2ff7e9595c
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