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Better blue LEDs

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LEDs have become the standard source of energy-efficient lighting.  They make use of semiconductors to turn electricity into light.  Depending upon the materials used to make them, LEDs produce different colors.  In the early 1990s, the first blue LEDs were discovered, ultimately earning the Nobel Prize in physics, and enabling LEDs to produce white light, which is essential for general lighting applications.

Blue LEDs have shortcomings.  Some have issues with stability, scalability, cost, efficiency, complexity in manufacturing, or have environmental concerns because of the use of toxic components. 

Researchers at Rutgers University in collaboration with scientists at several other institutions have found a way to make blue LEDs more efficient and sustainable.  These LEDs use a new type of hybrid material that is a combination of copper iodide with organic molecules.  The impressive performance of these LEDs was achieved through an innovative technique called dual interfacial hydrogen-bond passivation.  This new manufacturing technique boosts the performance of LEDs by a factor of four.

The material has several advantages.  It has a very high photoluminescence quantum yield, which means that it converts nearly all the photoenergy it receives into blue light.  The LEDs last longer than many others and they work well in larger-scale applications, maintaining high efficiency.  The materials are eco-friendly and cost-effective.

According to the researchers, this new approach could be a versatile strategy for generating high-performance LEDs that can pave the way for better, brighter, and longer-lasting LEDs.

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Scientists Develop Deep-Blue LEDs Expected to Greatly Enhance General Lighting

Photo, posted February 1, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Controlled Environment Agriculture | Earth Wise

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The term “controlled environment agriculture” (or CEA) refers to any number of systems embodying a technology-based approach to farming.  CEA can range from simple shade structures to greenhouses to full indoor or vertical farms.  At the most advanced level, CEA systems are fully automated, closed loop systems with controlled lighting, water, and ventilation.   Many systems make use of hydroponics rather than traditional soil.

The goal of CEA systems is to provide optimum growing conditions for crops and prevent disease and pest damage. 

A recent study by the University of Surrey in the UK sought to understand the impact of using CEA systems to grow lettuce, which is a high-value crop that is often grown in such systems.

The study found that, on average, CEA methods produce double the crop yields compared to field-based agriculture.  They also found that the cultivation time of CEA yields was, on average, 40 days.  This compares with an average cultivation time of 60-120 days for field-based agriculture.  More specifically, production of lettuce using CEA was 50% faster in the summer and up to 300% faster in the winter.

Climate change presents many difficult challenges to society, not the least of which is its threat to food security.  Controlled environment agriculture could allow cultivation of crops in harsh environments and in the face of changing climates.  Quantifying the benefits CEA can have on yield and growth provides important information for advancing our understanding of where and when this technology can bring the most value to society. 

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Using artificial methods for growing crops could help solve global food security

Photo, posted February 24, 2013, courtesy of Cindy Kurman / Kurman Photography via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar Power At Night | Earth Wise

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The use of solar power has grown tremendously in recent years as it has declined in price and become far more competitive with other forms of electricity generation.  Its fundamental drawback, of course, is that it only works when the sun is shining.  Solar panels don’t produce any power at night.  That is, until now, apparently.

A team of engineers at Stanford University have developed a new kind of solar cell that is capable of generating at least some electricity at night.  Published in the journal Applied Physics Letters, the research describes a device that can be a continuous renewable power source for both day and nighttime.

The device incorporates a thermoelectric generator that produces electricity from the small difference in temperature between the ambient air and the solar cell itself.  The amount of power produced is far less than the solar cell generates from sunlight, but the device can provide nighttime standby lighting and power in off-grid and mini-grid applications.

Mini-grid applications are independent electricity networks that are used for small populations that may be too isolated to be connected to the main power grid.  Nearly 600 million people in Africa currently live without access to electricity, primarily in rural areas.  A standalone solar system operating independently of any power grid can meet many electricity needs such as phone charging and lighting, but such systems may not be able to handle large electrical need such as powering machinery and agricultural equipment.  Mini-grids are larger installations that can provide power to a small rural community.

With innovations like the new Stanford device, a solar mini-grid may be able to keep running at some level even at night.

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Solar panels that can generate electricity at night have been developed at Stanford

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

Earth Wise is a production of WAMC Northeast Public Radio

Artificial Light And Nature | Earth Wise

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Most of us are familiar with air pollution, water pollution, soil pollution, and noise pollution.  But it turns out that light can also be a pollutant as well. 

Light pollution is a consequence of industrial civilization.  Sources of light pollution include building interior and exterior lighting, advertising billboards, factories, commercial properties, streetlights, and sporting venues.      

According to findings in a new report from the University of Exeter, artificial nighttime lighting has a wide range of effects across the natural world and should be limited wherever possible.  The research team analyzed more than 100 studies and found that artificial lighting has widespread impacts on both animals and plants. 

In the study, which was funded by the Natural Environment Research Council in the U.K., researchers consistently found changes to animals’ bodies and behavior as a result of artificial lighting.  In particular, levels of the sleep cycle-regulating hormone melatonin were reduced by exposure to artificial lighting at night in all animal species studied. 

Exposure to artificial nighttime lighting also affected the timing of animals’ activities.  For rodents, which are largely nocturnal, the duration of activity was often reduced by exposure to nighttime lighting.  On the other hand, for diurnal birds, exposure to nighttime lighting led to an extension of the duration of their activities.  

Previous studies have found other wide-ranging impacts of nighttime lighting, from reducing pollination by insects to trees budding earlier in spring.  

Artificial nighttime lighting is human driven and very disruptive to the natural world.  While there’s no off switch for the planet, we could reduce the amount of light pollution drastically with no impact on our lives. 

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Artificial night lighting has widespread impacts on nature

Photo, posted July 29, 2017, courtesy of spacedust2019 via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Benefits Of Zero-Carbon Cities

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A new report issued by a coalition of 50 leading international institutions shows that low carbon initiatives in cities could reduce urban emissions by nearly 90% and support 87 million jobs worldwide by 2030.  The report finds that implementing low carbon measures in cities would be worth almost $24 trillion by 2050.

Cities are home to more than half the world’s population but produce 80% of gross domestic product and 75% of carbon emissions.  The research highlights the significant benefits carbon reduction can bring to cities in areas such as public health, job creation, and poverty alleviation.

The report shows that it is possible to cut 90% of emissions from cities using currently available technologies and practices including carbon savings from buildings, transportation, materials efficiency, and waste reduction.  Doing so would require an investment of nearly $2 trillion per year but would generate annual returns of nearly $3 trillion in 2030 and $7 trillion in 2050 based on cost savings alone.  Many low carbon measures would pay for themselves in less than five years, including more efficient lighting, electric vehicles, improved freight logistics, and solid waste management.

In addition to economic benefits, compact, connected and clean cities could provide a higher standard of living and greater opportunity for all.  These measures would also reduce air pollution, cut chronic traffic congestion, and improve worker productivity.

The report offers case studies from around the world where national and local governments have worked together to rapidly and profoundly transform their cities for the better within 20 or 30 years.

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The benefits of investing in zero-carbon cities

Photo, posted September 8, 2018, courtesy of Steffen Flor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Speed Breeding Of Crops

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A technique pioneered by NASA for the purpose of growing plants extra-terrestrially is now being applied here on earth to fast-track improvements in a range of crops.  The technique, known as speed breeding, has been adapted for use by British and Australian researchers on a scale ranging from vast greenhouses to desktop growth chambers.

Speed breeding uses enhanced LED lighting and day-long regimes of up to 22 hours to optimize photosynthesis and promote rapid growth of crops.  By speeding up the breeding cycle of plants,it is possible, for example, to grow six generations of wheat in a year compared with two generations using traditional breeding methods.

With shortened breeding cycles, genetic improvements such as yield gain, disease resistance and climate resistance can be fast-tracked in crops such as wheat, barley, chickpeas, various Brassica species, oil seed rape and peas.

The ability to do this in compact desktop chambers permits cutting-edge research to be performed inexpensively before being scaled up to large greenhouses.

Crop development is an increasingly important activity and speed breeding is increasingly attractive in light of the opposition in some quarters to modern gene-editing techniques to create GMO crops.  Speed breeding allows crop improvements via anon-GMO route.

The new technique is already being applied in Australia, which is experiencing one of the worst droughts on record.  It is being used to rapidly cycle genetic improvements to make crops more drought resilient.

Generation time in most plant species is a major bottleneck in applied research programs and breeding.  Speed breeding can greatly reduce this bottleneck, allowing scientists to respond more quickly to emerging diseases, the changing climate and increased demand for specific plant traits.

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JIC joins European scientists to safeguard precision breeding

Photo, posted May 8, 2016, courtesy of Yair Aronshtam via Flickr. 

Earth Wise is a production of WAMC Northeast Public Radio.

Trends Influencing Our Cities

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The Environmental Protection Agency removed its information hub about climate change last year.  In response, 17 cities reposted the information on their own city government sites.  This is indicative of the fact that cities are increasingly taking on a leadership role in environmental, social and economic change.

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Disruptive Light Bulb Technology

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Investment companies like to talk about the disruptive nature of technologies and how they change industries while simultaneously changing our lives.  The growing emphasis on a low-carbon economy has spotlighted a number of technologies as being disruptive in their industry sectors.  One hears this frequently when discussing wind and solar power.  Clearly, these two technologies are changing the face of the utility industry, but at least at present, they still represent a fairly small fraction of the overall business.

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Energy Intensity

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Every stage of civilization is characterized by its use of energy.   From burning wood to steam engines to our electrified society, energy is behind everything we do.  Over time, human society has become increasingly energy intensive.  As our standards of living have improved and as we overcome the effects of weather – either cold or warm – it takes more and more energy to live the lives we lead.

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