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Windows To Cool Buildings | Earth Wise

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About 15% of global energy consumption is for cooling buildings.  Because of this, there is an ever- growing need for technologies that can more efficiently cool buildings.   Researchers at Notre Dame University have used advanced computing technology and artificial intelligence to design a transparent window coating that is able to lower the temperature inside buildings without using any energy.

The idea is to create a coating that blocks the sun’s ultraviolet and near-infrared light, which are parts of the solar spectrum that otherwise pass through glass and help to heat an enclosed room.  Cooling needs can be reduced further if the coating can radiate heat from the surface of the window so it can pass through the atmosphere into space.  Designing a coating that does both of those things simultaneously while transmitting visible light is difficult.  Coatings should not interfere with the view out the window.

The Notre Dame researchers used advanced computer modeling to create a so-called transparent radiative cooler that meets these goals.  The coating consists of alternating layers of common materials like silicon dioxide, silicon nitride, and aluminum oxide or titanium dioxide on top of a glass base and topped with a film of polydimethylsiloxane.  The computing method was able to optimize this structure far faster and better than conventional design techniques.

The researchers say that in hot, dry cities, the coating could potentially reduce cooling energy consumption by 31% compared with conventional windows.  The same materials could be used in other applications, such as car and truck windows.  In addition, the quantum computing-enabled optimization method used for this work could be used to design other composite materials.

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Clear window coating could cool buildings without using energy

Photo, posted September 6, 2015, courtesy of Robert Otmn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Plastic Recycling Isn’t Working | Earth Wise

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A recent report from several environmental organizations shows that plastic recycling rates in the U.S. have actually declined in the last several years from about 8.7% of discarded plastic to less than 6%.   Meanwhile, since 1980, per capita plastic waste generation has increased 263%, totaling 218 pounds of plastic waste per person as of 2018.

Diminishing recycling rates don’t necessarily indicate a lack of interest by the public.  Plastic recycling is a complicated process.  There are multiple types of plastic that can’t be intermingled and there are no simple and sustainable ways to recycle many forms of plastic.   On top of that, the declining recycling rate also reflects the fact that we no longer can export our plastic waste to countries like China and Turkey, which have banned U.S. waste imports.

Recycling in general is a successful practice.  Paper recycling rates are around 66% as of 2020.  Cardboard recycling was at 88.8% in 2020, and metal recycling rates range from 27% to 76%, depending on the type of metal.  Glass recycling rates are a little over 30%.  Only plastic recycling has never reached 10%, even before shipping our waste overseas and declaring it to be recycled was going on.

According to environmental organizations focused on the global plastic problem, there is no circular economy of plastics.  Perhaps if truly biodegradable plastics became practical, economical, and widely utilized, the situation would be different.  As things stand, the only solution is to reduce the production, use, and disposal of plastics.

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Plastics Recycling ‘Does Not Work,’ Environmentalists Stress as U.S. Recycling Rates Drop to 5%

Photo, posted May 13, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sand From Mining Waste | Earth Wise

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The natural resources people use the most are air and water.  It may come as a surprise that in third place is sand.  Sand is used to make glass, computer chips, toothpaste, cosmetics, food, wine, paper, paint, plastics, and more.  It is estimated that 50 billion tons of sand are used each year.

Concrete is 10% cement, 15% water, and 75% sand.  The concrete required to build a house takes on average 200 tons of sand, a hospital uses 3,000 tons, and a mile of a highway requires 15,000 tons.

One would think that there is no shortage of sand, but we are using it up faster than the planet can make it and the extraction of sand from seas, rivers, beaches, and quarries has negative impacts on the environment and surrounding communities.  For example, removing sand leads to erosion in riverbanks, significantly increasing the risk of flooding in some places.

A potential strategy to reduce the impact of extracting sand to meet society’s growing need for is also a strategy for helping to reduce the production of mineral mining waste, which is the largest waste stream on the planet.  Mining produces between 33 and 66 billion tons of waste material each year.

A new study by researchers in Switzerland and Australia looked at the potential for using mining waste as a source of so-called ore-sand.  Sand-like material left over from mining operations could be used for many current applications for sand.  Separating and repurposing these materials before they are added to the waste stream would not only reduce the volume of waste being generated by mining operations but would also create a responsible new source of sand.

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Solution to world’s largest waste stream: Make sand

Photo, posted October 22, 2005, courtesy of Alan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Window | Earth Wise

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Researchers at Oxford University have developed a new adaptable smart window technology that has the potential of reducing the energy usage of the average home by a third.

The technology uses a spectrally tunable low-emissivity coating that can control the amount of heat that comes into a room without affecting the quality of the light that enters.

The thermal energy from the sun’s infrared rays is absorbed by the glass and then is re-emitted as heat.  That heat can either be used to warm the room using transparent electrical heaters embedded in the glass or can be reflected away to cool the room.  The windows can change according to seasonal needs.

The researchers built a prototype using a material called an active chalcogenide-based phase change material.  When it is cold, the infrared rays from the sunlight are harvested and used to heat the building.  When it is warm, the new glass can switch state to reflect the heat and reduce the need for air conditioning.  The active phase change material is adjustable so that the amount of heat absorbed or reflected can be tuned for precise temperature control.  There is essentially no effect on visible light passing through the window.  Current low-emissivity glass for windows can reduce heat transfer, but its properties cannot be altered according to seasonal needs.

The researchers estimate that using windows fitted with the new prototype glass – including the energy required to control the film – would save 20 to 34% in energy usage annually compared to double-glazed windows found in many modern homes.

A spinout company from Oxford called Bodle Technologies is collaborating with two existing industrial partners to develop the technology further.

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New adaptable smart window coating could help heat or cool a home and save energy

Photo, posted April 26, 2008, courtesy of Lima Andruska via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Heat-Blocking Window | Earth Wise

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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.

Plant-Based Bottles | Earth Wise

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Single-use plastic soda and water bottles are a real problem.  Every year, billions of them are produced – comprising nearly 300 million tons of plastic that mostly ends up in landfills or in the ocean.   This discarded plastic ends up on remote islands, in the snow atop mountains, and in trenches in the deepest parts of ocean.

There has been increasing pressure on beverage companies to put an end to this environmental disaster, but the convenience and economy of disposable bottles is just too attractive.

These bottles are made of plastic derived from oil and once they are produced, they take decades or even centuries to decompose.  Recycling them is a not-starter because it is cheaper to just make new ones.

A possible solution has emerged.  A Dutch company called Avantium has found a way to take plant sugars and transform them into a plastic capable of standing up to carbonated beverages like soda and beer but that will also break down in as little as a year in a composter or 3 years if left exposed to the elements.

Coca Cola and Carlsberg are working with Avantium to develop new drink packaging based on their material that could be in stores as soon as 2023.  The new packaging would be quite different from what we use today.  Instead of a clear or tinted bottle, beverages would come inside a cardboard container with a liner made of plant-based plastic.

It may take a while for people to get used to the change, but we have already managed to get used to milk, juice and other liquids coming in cardboard containers instead of glass or plastic bottles.  The benefits to the planet would make the effort well worthwhile.

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Plant-Based Bottles Could Degrade In One Year

Photo courtesy of Avantium.

Earth Wise is a production of WAMC Northeast Public Radio.

Extreme Heat From Solar Power | Earth Wise

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Renewable sources are playing a growing role in meeting our energy needs, but one place where they have continued to fall short is in industrial processes that require extreme heat.  These include the cement, steel, and glass industries, among others.  These industries account for a significant amount of CO2 emissions because the most effective way to reach the necessary temperatures continues to be combustion of fossil fuels.  The cement industry alone accounts for 7% of global emissions and the need for cement continues to grow.

A previously stealthy startup company backed by Bill Gates and fellow billionaire Soon-Shiong has made a breakthrough in the area of using solar energy to achieve high temperatures.  The company, called Heliogen, has created a solar oven that is capable of generating heat above 1800 degrees Fahrenheit, which is enough for high-temperature industrial processes.

The Heliogen technology uses concentrated solar power to generate heat.  Concentrated solar power uses arrays of mirrors to reflect sunlight and focus it to a single point.  That technology is not new;  there are systems that use it to produce electricity and, to some extent, heat for industry.  But it could not achieve high enough temperatures for producing cement or steel.

The new system uses computer vision software, automatic edge detection and other sophisticated technologies to focus the sun’s rays far more finely than ever before and thereby generate far higher temperatures at the focal point.

Heliogen is now focused on demonstrating how the technology can be used in a large-scale application, such as cement-making.  The selling points to industry are that not only will there be no emissions generated, but that the fuel needed to obtain their extreme heat will be free.

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Secretive energy startup backed by Bill Gates achieves solar breakthrough

Photo courtesy of Heliogen.

Earth Wise is a production of WAMC Northeast Public Radio.

Sand Mining And The Environment

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In discussions of the environment, we don’t hear much about sand mining.  But sand mining is the world’s largest mining endeavor, responsible for 85% of all mineral extraction.  Sand and gravel are mined on a huge scale around the world.  The UN estimates that the total exceeds 40 billion tons a year.  Most of this activity is unregulated and unmeasured, and much of it is corrupt and environmentally destructive.

Concrete is the predominant use for sand.  Every ton of cement requires six to seven tons of sand and gravel in order to make concrete.  But sand also makes up 90% of asphalt on roads and it is used for land reclamation in places like Singapore.  Sand is also widely used in industries such as glass manufacturing and fracking.

There are different sorts of sand.  Desert sand is mostly useless for making concrete because its grains are too rounded by erosion and don’t bind well in the concrete.   Marine sand is not great for concrete either because it has to be washed clean of corrosive salts.

As a result, salt miners mostly get sand from pits on land and dredged up from lakes and riverbeds.  Dredging massive quantities of sand from rivers and lakes drastically alters river flow, erodes riverbanks, dries up tributaries, lowers water tables, and trashes wetlands and fisheries.  In many countries, this even goes on in national parks where officials turn a blind eye to the activity.  India is the world’s second-largest sand mining country (after China) and widespread illegal extraction occurs throughout the country run by highly organized and even violent “sand mafias.”

Sand mining is a huge problem and, to date, is one that is pretty much off of most people’s radar.

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The Hidden Environmental Toll of Mining the World’s Sand

Photo, posted June 3, 2017, courtesy of Andrey Talalov via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Car Parts From Agricultural Waste

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A new bio-composite material made from date palm fiber biomass could be used to produce sustainable, lightweight and low-cost parts for the automobile and marine industries.

A team of researchers from the UK has developed a date palm fiber polycaprolactone composite that is completely biodegradable, renewable,sustainable and recyclable, in contrast to synthetic composite materials reinforced by glass and carbon fibers. The team tested the mechanical properties of the material and found that it achieved better low-velocity impact resistance than traditional man-made composites.

The idea would be to use the material in non-structural auto parts such as car bumpers and door linings.   The result would be to reduce the weight of vehicles, contributing to less fuel consumption and lower emissions.  The new material can be produced using less energy than glass and carbon fibers and is biodegradable and therefore easier to recycle.

Date palm fibers are one of the most available natural fibers in many parts of the world.  The trees produce a large quantity of agricultural waste, which is mostly burned or land-filled,causing serious environmental problems.

Convincing industry to use a new class of materials such as natural-fiber reinforced composites is challenging.  First it is necessary to obtain consistent,reliable properties from the material. Then the industries need to work closely with the developers to test the materials and convince themselves of the viability of using them.  The team, led by researchers at the University of Portsmouth, has been working with industry to test the viability of parts made from a variety of other sustainable materials as well including flax, hemp, and jute.  Someday, our cars may have bumpers made from agricultural waste.

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Agricultural waste drives us closer to greener transport

Photo, posted October 27, 2017, courtesy of David Stanley via Flickr. 

Earth Wise is a production of WAMC Northeast Public Radio.

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