durability

Colorful Solar Panels | Earth Wise

September 22, 2022 By EarthWise Leave a Comment

More and more buildings and public spaces are incorporating solar panels and not only just on rooftops. Some buildings are incorporating power-generating structures all over their facades.

Using solar panels in this way puts some design constraints on buildings because solar panels are typically a deep black color. This is because solar panels need to absorb light and making them any other color decreases their ability to do so and generate power. But the problem is that people don’t necessarily want a black building.

One alternative to traditional solar panel design is to use structural sources of color that include microscopic shapes that only reflect specific light frequencies, like the scales on butterfly wings. But this approach generally leads to iridescence – which might not be what is wanted – and is often quite expensive to implement.

A team of researchers at a university in Shanghai has now demonstrated a way to give solar panels color that is easy and inexpensive to apply and that does not reduce their ability to produce energy efficiently.

The technique involves spraying a thin layer of a material called a photonic glass onto the surface of solar cells. The photonic glass is made of a thin, disorderly layer of dielectric microscopic zinc sulfide spheres. Even though most light can pass through the photonic glass, certain colors are reflected back, depending on the sizes of the spheres. By varying that size, the researchers created solar panels that were blue, green, or purple with only a very small drop in solar panel efficiency.

The solar panels made this way maintained their color and performance under durability testing. With this new technology, there may soon be colorful solar panels on our buildings.

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Colorful solar panels could make the technology more attractive

Photo, posted December 15, 2021, courtesy of Pete via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Progress On Perovskite Solar Cells | Earth Wise

August 2, 2022 By EarthWise Leave a Comment

Perovskites are semiconductors with a specific crystal structure. Their properties make them well suited for making solar cells. They can be manufactured at room temperature, using much less energy than it takes to make the silicon-based solar cells widely used today. As a result, perovskite solar panels would be cheaper and more sustainable to produce. Manufacturing silicon solar cells takes a lot of energy because silicon is forged at around 3000 degrees Fahrenheit. In addition, perovskites can be made flexible and transparent, making it possible to use them in ways unavailable with silicon solar technology.

But unlike silicon, perovskites are very fragile. The early solar cells made from perovskites in 2009 and 2012 lasted for only minutes. Lots of potential, but little practicality.

Recently, Princeton Engineering researchers have developed the first perovskite solar cell with a commercially viable lifetime, which is a major breakthrough. The team projects that the device can perform above industry standards for about 30 years, which is much more than the 20 years designated as a viability threshold for commercial cells.

The research team has developed an ultra-thin capping layer between two of the layers of a perovskite solar cell. The layer is just few atoms thick but has been demonstrated to dramatically increase the durability of the device.

There is great potential for the new solar cell technology. It has efficiency to compete with silicon cells but can be tuned for specific applications and can be manufactured locally with low energy inputs. If successfully commercialized, the result will be solar panels that are cheaper, more efficient, and more flexible than what are available today.

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Once seen as fleeting, a new solar tech shines on and on

Photo, posted January 8, 2020, courtesy of David Baillot/UC San Diego Jacobs School of Engineering via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Heat-Blocking Window | Earth Wise

December 9, 2021 By EarthWise Leave a Comment

An international research team led by Nanyang Technological University in Singapore has invented a ‘smart’ window material that controls the transmission of heat without blocking the view through the window. The technology could help reduce the amount of energy needed to cool and heat buildings.

The new material can be the basis of an electrochromic window that can block or pass infrared radiation at the flick of a switch. Current electrochromic windows can be darkened when switched on and are found in many ‘green’ buildings as well as in many car mirrors. But these windows are only effective in blocking visible light so infrared radiation – meaning heat – still passes through them.

The new coating material blocks up to 70% of infrared radiation when switched on but still allows up to 90% of visible light to pass through. The material is a specifically designed composite nanostructure and utilizes advanced materials including titanium dioxide, tungsten trioxide, neodymium, niobium, and tin oxide. It is intended to be coated onto glass window panels and be activated by electricity when needed. The material was put through rigorous on-off cycles to assess its stability and durability and it appears to offer superior performance in that regard compared with current electrochromic technology.

The researchers also created a switchable system that helps control conducted heat, which is the heat from the external environment.

The combination of the two technologies could result in smart windows that control two types of heat transmission: infrared radiation and conduction heat. Such technology could help conserve energy used for the heating and cooling of buildings and could contribute to the future design of sustainable green buildings.

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Scientists invent ‘smart’ window material that blocks rays without blocking views

Photo, posted March 11, 2016, courtesy of Open Grid Scheduler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Improving Solar Cells With Human Hair | Earth Wise

June 1, 2021 By EarthWise Leave a Comment

Researchers at the Queensland University of Technology in Australia have been able to improve the performance of perovskite solar cells using material made from human hair.

Perovskite solar cells are an up-and-coming technology that offers the possibility of making solar cells less expensive, more efficient, and flexible so that there could be solar-powered clothing, backpacks, or even tents for camping. While the technology has been shown to be as effective in converting sunlight to electricity as currently available silicon technology, it faces problems with stability and durability.

The Australian research centered on the use of carbon nanodots to improve perovskite solar cell performance. The nanodots were created in a rather unique way. The carbon came from hair scraps from a Brisbane barbershop that were first broken down and then burned at nearly 500 degrees Fahrenheit.

By adding a solution of the carbon nanodots into the process of making the perovskites, the dots formed a wave-like layer in which the perovskite crystals in the cells are surrounded by the carbon dots. It serves as a protective layer, essentially a kind of armor, for the active portions of the material.

The result was solar cells with a higher power conversion efficiency and greater stability. The researchers did not explain why they chose human hair as the source of carbon, but it does make for an interesting sidelight to the promising research.

Perovskite solar cells could be very important for spacecraft applications where reducing weight is paramount. But in order to be able to use them for this purpose, perovskite solar cells will need to be able to cope with the extreme radiation and temperature variations in space.

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Carbon dots from human hair boost solar cells

Photo, posted October 3, 2009, courtesy of Arktoi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Turning Wood Into Plastic | Earth Wise

May 4, 2021 By EarthWise Leave a Comment

Plastic pollution is particularly pernicious because plastics can take hundreds of years to degrade in the environment. For this reason, researchers across the globe search for ways to shift from petrochemical plastics to ones that are biodegradable.

Producing biodegradable plastics is challenging both from the standpoint of the methods needed and from the results obtained. Producing them often requires toxic chemicals and can be very expensive. The materials that emerge often do not have the durability and strength of conventional plastics and can be unstable when exposed to moisture.

Researchers at the Yale School of the Environment have developed a process of decomposing the porous matrix of natural wood into a slurry that can be formed into a biodegradable plastic. The material shows high mechanical strength, stability when holding liquids, and is resistant to the effects of ultraviolet light. Along with all these favorable properties, the material can be recycled or safely biodegraded in the natural environment.

The slurry mixture is created by taking wood powder – a processing residue usually discarded in lumber mills – and deconstructing it with a biodegradable and recyclable solvent. The resulting mixture has a high solid content and high viscosity and can be casted and rolled without breaking.

The researchers conducted a comprehensive life cycle assessment to test the environmental impacts of the bioplastic compared with conventional plastics. Sheets of it were buried in soil and observed to fracture after two weeks and completely degrade after three months. The material can also be broken back down into the slurry by mechanical stirring.

The remaining topic to investigate is the potential impact on forests if the manufacturing of this bioplastic is scaled up.

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Turning wood into plastic

Photo, posted October 12, 2016, courtesy of the US Forest Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Breaking Down Polystyrene | Earth Wise

April 20, 2021 By EarthWise Leave a Comment

The proliferation of global plastic waste continues to be a growing problem for the world. Hundreds of millions of tons of plastics are produced each year and most of it is used once and then discarded. The properties that make plastics so attractive – durability and chemical stability – make it difficult to do anything with discarded plastics other than deposit them in landfills – where they don’t easily degrade over time – or burn them, which dumps carbon dioxide and various hazardous gases into the atmosphere.

Polystyrene is one of the most widely used plastics. It is found in foam packaging materials, disposable food containers, plastic cutlery, storage containers, and many other places.

Recycling plastics like polystyrene is generally not economically feasible. Sorting plastics by type is time and labor intensive and the chemical processes required to break down plastics into usable precursor materials require significant energy input and the use of toxic solvents.

Recently, a team of scientists at Ames Laboratory in Iowa has developed a process based on ball-milling that deconstructs commercial polystyrene in a single step, at room temperature, in ambient atmosphere, and in the absence of harmful solvents.

Ball-milling is a technique that places materials in a milling vial with metal ball bearings which is then agitated to initiate a chemical reaction. This approach is known as mechanochemistry.

The method represents an important breakthrough that enables dismantling of a polymer that includes its chemical breakdown without requiring solvents or the high temperatures generally needed to thermally decompose it. This discovery opens up new avenues for low-temperature recovery of monomers from polymer-based systems that include composites and laminates. It could be a very useful weapon in the battle against plastic waste.

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Polystyrene waste is everywhere, and it’s not biodegradable. Scientists just found a way to break it down.

Photo, posted December 11, 2010, courtesy of Warrenski via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Replacing Plastic Tableware | Earth Wise

December 30, 2020 By EarthWise Leave a Comment

Plastics have been described as the “ubiquitous workhorse material of the modern economy.” But their versatility, pliability, and durability comes at a heavy price to the environment. Plastic pollution is quite literally everywhere. Plastic debris and microplastic particles can be found in every corner of the globe, including the Arctic and Antarctic.

The scourge of plastic pollution is driving scientists to create ecologically-friendly alternatives. According to a paper recently published in the journal Matter, scientists have developed “green” tableware made from sugarcane and bamboo that doesn’t sacrifice on convenience or functionality. This eco-friendly tableware could serve as a permanent replacement for plastic cups and other disposable plastic containers.

Traditional plastic polymers, a product of petroleum, can take as long as 1,000 years to decompose in landfills. The new material only takes 60 days to break down.

To create this material, scientists used bamboo and bagasse, also known as sugarcane pulp. Bagasse is one of the largest food-industry waste products. The researchers wound the fibers together to form a mechanically stable and biodegradable material. They added an alkyl ketene dimer, an eco-friendly chemical, to increase the oil and water resistance of the material. The green material is durable enough to hold liquids like hot coffee and hot greasy foods like pizza.

There’s another advantage: the green material’s manufacturing process emits 97% less CO2 than the process to make commercial plastic containers. The next step is to lower the manufacturing cost. While the cost of cups made from the green material is $2,333 per ton, traditional cups made from plastic are still slightly cheaper at $2,177 per ton.

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This tableware made from sugarcane and bamboo breaks down in 60 days

Photo, posted May 19, 2013, courtesy of Henry Burrows via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Keep Track Of Your LEGOs | Earth Wise

April 9, 2020 By EarthWise Leave a Comment

Plastics in the ocean are a global problem that has attracted a great deal of attention. Most of the concern surrounds grocery bags, bottles, six-pack rings, and similar items. Recent research looked at another source of plastic pollution: LEGOs.

According to environmental scientists at the University of Plymouth in the United Kingdom, it can take more than a thousand years for LEGO bricks to break down in the ocean. The iconic toys are made from a strong plastic called acrylonitrile butadiene styrene or ABS. Pieces of LEGOs are commonly found in ocean trash hotspots and wash up on shores across the globe by the thousands.

LEGOs are one of the most popular children’s toys in history and part of what makes them so popular is their durability. Barefooted parents stepping on one on the floor in a dark room can attest to that fact. But the full extent of their durability came as a surprise to the researchers.

The scientists analyzed pieces of weathered LEGOs collected from beaches, confirmed their age, and compared them to unweathered LEGOs from the 70’s and 80’s. They were able to determine the extent to which LEGOs had been worn down by ocean waves, sand, and salt over time. And it was surprisingly little.

LEGO has acknowledged the environmental impact of its products and has launched a goal to make its bricks from more sustainable sources such as sugarcane-based polyethylene by 2030, as well as improve its efforts to recycle and reuse old LEGO plastic.

Meanwhile, we should all we careful of where our old LEGOs end up.

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LEGO Bricks Could Linger in the Ocean for 1,300 Years, Study Finds

Photo, posted August 24, 2015, courtesy of Juan Luis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Way To Make Solar Cells

March 21, 2019 By EarthWise Leave a Comment

Millions of rooftops now contain solar panels and the majority of the solar cells that make up those panels today are made from silicon. Silicon solar cells require expensive, multi-step processing conducted at very high temperatures in special clean room facilities. Despite these complications, the price of solar panels has continued to drop dramatically over the years.

But even as the price of solar cells gets lower and lower, there are still widespread efforts to find even better ways to make them. One of those ways is with perovskite solar cells. Perovskites are materials with a characteristic crystal structure and are quite common in nature. Perovskites can be formed with a wide range of elements and can exhibit a variety of properties.

They were first used to make solar cells about 10 years ago and those first cells were unimpressive in most respects. However, there has been steady progress since that time. The potential advantages of perovskite solar cells are that they can be made from low-cost materials and can be manufactured using liquid chemistry, a far cheaper process than what is used to make silicon cells.

Researchers at MIT and several other institutions have recently published the results of research on how to tailor the composition of perovskite solar cells to optimize their properties. What used to be a trial-and-error process can now become much more engineered and should lead to perovskite solar cells with performance that could exceed that of silicon cells.

Silicon solar panels are a huge, worldwide industry and displacing them in favor of an alternative technology is a tall order. But if perovskite cells can be optimized for large-scale manufacturability, efficiency and durability, they could definitely give silicon a run for its money.

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Unleashing perovskites’ potential for solar cells

Photo courtesy of Ken Richardson/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

Recycled Plastic Lumber

July 20, 2016 By WAMC WEB

One of the most notable success stories in recycling is that of structural plastic lumber. The material is mostly polyethylene reinforced with stiff plastics or recycled composites. Made from milk containers, coffee cups, and other recycled plastics, structural plastic lumber is lighter than steel, longer-lasting than natural lumber and strong enough to support 120-ton locomotives.