Google, Levi’s Create “Smart” Denim Jacket for Urban Cyclists

By: Jasmin Malik Chua

There’s very little about Google and Levi Strauss’s “smart” jacket that distinguishes it from any other garment a savvy urbanite might sport. With neither flashing LEDs nor conspicuous circuits, the “Commuter” trucker doesn’t exactly telegraph “high-tech.” Yet that is precisely the point. Unveiled at Google I/O on Friday, the denim topper is the result of yearlong efforts by Project Jacquard, a collaboration between the technology giant’s Advanced Technology and Projects group and Levi’s own innovation division to create interactive textiles that fashion designers can adopt with minimal know-how. All moving parts are as close to invisible as you can get: Project Jacquard has literally woven the conductive yarns and their attendant electronics into the fabric of the jacket. In other words, Google Glass this ain’t.

Urban cyclists stand to benefit the most from the technology, which allows users to access their smartphones without having to physically pull them out. By tapping or swiping the “smart tag” on the cuff of a sleeve, wearers can answer—or dismiss—phone calls, skip music tracks, or turn on voice navigation—all without taking their eyes off the road.

Plus, remove the detachable tag and the entire garment is machine washable—just like regular denim.

“Anyone on a bike knows that navigating your screen while navigating busy city streets isn’t easy—or a particularly good idea,” Paul Dillinger, head of global product innovation for Levi Strauss, said in a statement. “This jacket helps to resolve that real-world challenge by becoming the co-pilot for your life, on and off your bike.”

The jacket, he added, will be available in spring 2017 at select Levi’s stores and online.


Harnessing Solar and Wind Energy in One Device could Power the ‘Internet of Things’

Hybrid solar and wind harvesting cells on the top of this model house collect enough energy to light it up inside. Credit: American Chemical Society

The “Internet of Things” could make cities “smarter” by connecting an extensive network of tiny communications devices to make life more efficient. But all these machines will require a lot of energy. Rather than adding to the global reliance on fossil fuels to power the network, researchers say they have a new solution. Their report on a single device that harvests wind and solar energy appears in the journal ACS Nano.

Computer industry experts predict that tens of billions of gadgets will make up the Internet of Things within just five years, according to news reports. They’ll be in homes, syncing coffee makers to alarm clocks. They’ll be in buildings, managing lights and air temperature. But they’ll also require energy to run. Sustainably generating more energy in cities close to where the devices will be used is challenging. Cities don’t have much space for towering wind turbines, for example. Ya Yang, Zhong Lin Wang and colleagues wanted to find a better way to power smart cities.

For the first time, the researchers have integrated two energy harvesting technologies in one: a silicon solar cell and a nanogenerator that can convert wind energy into electrical output. The solar cell component of the system delivers 8 milliWatts of power output (1 milliWatt can light up 100 small LEDs). The wind harvesting component delivers up to 26 milliWatts. Together, under simulated sun and wind conditions, four devices on the roof of a model home could turn on the LEDs inside and power a temperature-humidity sensor. Installed in large numbers on real rooftops, the hybrid device could help enable smart cities.


BMW Rolls Out New Solar Carports in South Africa

The solar carport rollout is part of the German automaker’s global efforts to expand home and publicly accessible charging infrastructure for electric vehicles.

BMW’s solar carport is made of high-end bamboo and stainless steel housing for the glass solar modules. BMW

German automaker BMW has unveiled its new solar carports in South Africa, which it will begin rolling out in July.

The BMW i solar carport supplies an average of 3.6 kW of solar power straight to the BMW i Wallbox, which is used to charge electric and plug-in hybrid BMW models and which is equipped with a live readout of how much power is being generated by the sun.

Tim Abbott, CEO of BMW Group South Africa and Sub-Sahara, said the company was the first automaker to offer such a broad-based EV smart charging product to reduce costs for customers. The rollout is part of the company’s global efforts to expand home and publicly accessible charging infrastructure for electric vehicles, Abbott added.

In the coming months, BMW Group South Africa will expand the installation of the solar carport in major cities, including Johannesburg, Cape Town and Durban, for public charging.

Customers and fleet companies will also be able to order the solar carport for home and office charging.

“We have always emphasised that in order for electric vehicles and plug-in hybrid electric vehicles to be successful, we need to firstly increase consumer confidence in the viability of electric vehicles and secondly make public charging easily accessible for customers who purchase these cars,” Abbott said. “The rollout of the solar carport is also an emphasis on this philosophy.”

The solar carport is produced by PV solar system designer and installer Sunworks. It is made of high-end bamboo and stainless steel housing for the glass solar modules.

Bamboo is considered a particularly sustainable and high strength-to-weight ratio natural composite material useful for structures, BMW said.


Hot New Solar Cell

While all research in traditional photovoltaics faces the same underlying theoretical limitations, MIT PhD student David Bierman says, “with solar thermal photovoltaics you have the possibility to exceed that.” In fact, theory predicts that in principle this method could more than double the theoretical limit of efficiency, potentially making it possible to deliver twice as much power from a given area of panels. Photo courtesy of the researchers.

System converts solar heat into usable light, increasing device’s overall efficiency.

By: David L. Chandler

A team of MIT researchers has for the first time demonstrated a device based on a method that enables solar cells to break through a theoretically predicted ceiling on how much sunlight they can convert into electricity.

Ever since 1961 it has been known that there is an absolute theoretical limit, called the Shockley-Queisser Limit, to how efficient traditional solar cells can be in their energy conversion. For a single-layer cell made of silicon — the type used for the vast majority of today’s solar panels — that upper limit is about 32 percent. But it has also been known that there are some possible avenues to increase that overall efficiency, such as by using multiple layers of cells, a method that is being widely studied, or by converting the sunlight first to heat before generating electrical power. It is the latter method, using devices known as solar thermophotovoltaics, or STPVs, that the team has now demonstrated.

The findings are reported this week in the journal Nature Energy, in a paper by MIT doctoral student David Bierman, professors Evelyn Wang and Marin Solja?i?, and four others.

While all research in traditional photovoltaics faces the same underlying theoretical limitations, Bierman says, “with solar thermophotovoltaics you have the possibility to exceed that.” In fact, theory predicts that in principle this method, which involves pairing conventional solar cells with added layers of high-tech materials, could more than double the theoretical limit of efficiency, potentially making it possible to deliver twice as much power from a given area of panels.

“We believe that this new work is an exciting advancement in the field,” Wang says, “as we have demonstrated, for the first time, an STPV device that has a higher solar-to-electrical conversion efficiency compared to that of the underlying PV cell.” In the demonstration, the team used a relatively low-efficiency PV cell, so the overall efficiency of the system was only 6.8 percent, but it clearly showed, in direct comparisons, the improvement enabled by the STPV system.

The basic principle is simple: Instead of dissipating unusable solar energy as heat in the solar cell, all of the energy and heat is first absorbed by an intermediate component, to temperatures that would allow that component to emit thermal radiation. By tuning the materials and configuration of these added layers, it’s possible to emit that radiation in the form of just the right wavelengths of light for the solar cell to capture. This improves the efficiency and reduces the heat generated in the solar cell.

The key is using high-tech materials called nanophotonic crystals, which can be made to emit precisely determined wavelengths of light when heated. In this test, the nanophotonic crystals are integrated into a system with vertically aligned carbon nanotubes, and operate at a high temperature of 1,000 degrees Celsius. Once heated, the nanophotonic crystals continue to emit a narrow band of wavelengths of light that precisely matches the band that an adjacent photovoltaic cell can capture and convert to an electric current. “The carbon nanotubes are virtually a perfect absorber over the entire color spectrum,” Bierman says, allowing it to capture the full solar spectrum. “All of the energy of the photons gets converted to heat.” Then, that heat gets re-emitted as light but, thanks to the nanophotonic structure, is converted to just the colors that match the PV cell’s peak efficiency.

In operation, this approach would use a conventional solar-concentrating system, with lenses or mirrors that focus the sunlight, to maintain the high temperature. An additional component, an advanced optical filter, lets through all the desired wavelengths of light to the PV cell, while reflecting back any unwanted wavelengths, since even this advanced material is not perfect in limiting its emissions. The reflected wavelengths then get re-absorbed, helping to maintain the heat of the photonic crystal.

Bierman says that such a system could offer a number of advantages over conventional photovoltaics, whether based on silicon or other materials. For one thing, the fact that the photonic device is producing emissions based on heat rather than light means it would be unaffected by brief changes in the environment, such as clouds passing in front of the sun. In fact, if coupled with a thermal storage system, it could in principle provide a way to make use of solar power on an around-the-clock basis. “For me, the biggest advantage is the promise of continuous on-demand power,” he says.

In addition, because of the way the system harnesses energy that would otherwise be wasted as heat, it can reduce excessive heat generation that can damage some solar-concentrating systems.

To prove the method worked, the team ran tests using a photovoltaic cell with the STPV components, first under direct sunlight and then with the sun completely blocked so that only the secondary light emissions from the photonic crystal were illuminating the cell. The results showed that the actual performance matched the predicted improvements.

“A lot of the work thus far in this field has been proof-of-concept demonstrations,” Bierman says. “This is the first time we’ve actually put something between the sun and the PV cell to prove the efficiency” of the thermal system. Even with this relatively simple early-stage demonstration, Bierman says, “we showed that just with our own unoptimized geometry, we in fact could break the Shockley-Queisser limit.” In principle, such a system could reach efficiencies greater than that of an ideal solar cell.

The next steps include finding ways to make larger versions of the small, laboratory-scale experimental unit, and developing ways of manufacturing such systems economically.

This represents a “significant experimental advance,” says Peter Bermel, an assistant professor of electrical and computer engineering at Purdue University, who was not associated with this work. “To the best of my knowledge, this is a new record for solar TPV, using a solar simulator, selective absorber, selective filter, and photovoltaic receiver, that reasonably represents actual performance that might be achievable outdoors.” He adds, “It also shows that solar TPV can exceed PV output with a direct comparison of the same cells, for a sufficiently high input power density, lending this approach to applications using concentrated sunlight.”

The research team also included MIT alumnus Andrej Lenert PhD ’14, now a research fellow at the University of Michigan, MIT postdocs Walker Chan and Bikram Bhatia, and research scientist Ivan Celanovic. The work was supported by the Solid-State Solar Thermal Energy Conversion (S3TEC) Center, funded by the U.S. Department of Energy.





Solar Panel Turns Raindrops Into Power


An innovative solar panel technology could turn raindrops into electric power, according to scientists in China.

The new solar cell design, which can be “triggered” by both rain and sun, is described in a paper published in the Angewandte Chemie journal.

“All-weather solar cells are promising in solving the energy crisis,” explain the scientists from Ocean University of China and Yunnan Normal University, noting that the technology combines an electron-enriched graphene electrode with a dye-sensitized solar cell. “The new solar cell can be excited by incident light on sunny days and raindrops on rainy days,” they add.

Dye-sensitized solar cells are thin-film photovoltaic cells that harness organic dye to absorb sunlight and produce electrons, thereby creating energy.

The new technology could guide the design of advanced all-weather solar cells, according to the scientists.

The Science News Journal notes that, by using a thin layer of highly conductive graphene, the solar cell could effectively harness power from rain. “The salt contained in rain separates into ions (ammonium, calcium and sodium), making graphene and natural water a great combination for creating energy,” it reports. “The water actually clings to the graphene, forming a dual layer (AKA pseudocapacitor) with the graphene electrons. The energy difference between these layers is so strong that it generates electricity.”

Vasilis Fthenakis, a senior research scientist and adjunct professor at Columbia University who did not participate in the paper, told that, if the technology’s additional costs and potential solar cell optical losses do not exceed the benefits of rain-harvested energy, it could be used in climates not typically associated with strong solar energy. “The dye-sensitized cells where this is applied are not the type of technology that would be deployed globally as a replacement of conventional energy; they have applications mostly in diffuse-light applications, not in the high sun regions,” he said, via email.

Optical loss refers to potential solar cell energy lost through, for example, reflection or transmission.

China is one of the world’s major solar panel manufacturing bases and expects to significantly increase its own use of the technology over the coming years. In an attempt to reduce its carbon emissions, the country wants to triple its solar power capacity to as much as 143 gigawatts by 2020, according to a recent Bloomberg report.

U.S. firms are also looking to drive solar energy innovation. Last year SolarCity, which was co-founded by Tesla CEO Elon Musk, announced that it will make its most-cutting-edge solar panels in the United States. The San Mateo, Calif.-based firm will build its most-efficient rooftop solar panels at a huge new facility in Buffalo, N.Y. The factory is expected to reach full capacity in 2017.