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Protecting coastal areas with tidal range electricity generation

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Tidal range electricity generation uses the water level difference between high and low tides to operate generator turbines.  The method requires the construction of barrages and sluices to capture water during high tides and then release it during generation at low tide.  Tidal range generation is predictable renewable energy driven by the gravitational pull of the moon and sun.

It is only a practical scheme in those places that have large tidal ranges.  The largest tidal range in the world is in the Bay of Fundy in Canada.  The second largest is the Severn Estuary, in the UK.  Tidal ranges are large in many places around Britain’s coasts. But they are also vulnerable to flooding and surges from rising seas.

A new study by Lancaster University in the UK has found that the environmental and economic benefits are huge because tidal range barrages can protect coastal areas from flooding and sea level rise. With two-way generation and pumping, the full range of existing tides can be maintained to protect and support low-lying intertidal areas such as saltmarshes and mudflats. High tides can be limited to existing levels simply by closing sluices and running turbines and low tide levels can be maintained by pumping.  The study determined that with modern technology and operating procedures, these so-called estuarine barrages may be the only practical way to protect vital coastal habitats.

Earlier work by the researchers found that tidal range projects under commercial consideration in the UK can produce about 5% of the country’s electricity use and additional projects are feasible for 4 or 5 times as much generation.

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How tidal range electricity generation can protect coastal areas from flooding

Photo, posted August 17, 2014, courtesy of Andrea via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Geoengineering could create winners and losers

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Geoengineering – deliberate interventions to alter the climate and curb climate change – is a controversial topic, to say the least.  Once practically considered taboo even to discuss, there in increasing interest in at least exploring various ideas about how to halt or reverse climate change through direct actions that impact global temperatures.

Putting aside the very real concerns about the risks and dangers associated with such action, there is also the issue that climate interventions may create dramatically different effects across the globe, benefitting some areas and adversely affecting others.

A recent study by scientists at Rutgers University tackled this very issue.  Published in the journal Nature Food, it described the results of computer models simulating the impacts of stratospheric aerosol intervention (SAI), which is spraying sulfur dioxide into the stratosphere, where it would partially shield the Earth from the Sun, lowering temperatures.

The study looked at 11 different SAI scenarios and found that none of them benefitted everyone.  Uncontrolled global warming favors crop production in cold, high-latitude areas such as Canada, Russia, Scandinavia, and our northern border states.  Moderate amounts of SAI favors food production in the mid-latitudes (such as in the US and Europe.)  Large amounts of intervention favors agricultural production in the tropics. 

Even if geoengineering might not have dire consequences – which is by no means certain – it would create winners and losers.  Nations may have different ideas of what constitutes an optimal global temperature.  So, who gets to decide where to set the global thermostat?  The prospects for conflict loom large. 

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Climate Intervention Technologies May Create Winners and Losers in World Food Supply

Photo, posted November 18, 2021, courtesy of Conall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Powering Britain with sun and wind

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The United Kingdom is quite small in size compared with the US, but its population of 67 million makes it a fairly large country with substantial energy needs.  A recent study by Oxford University looked at the ability of wind and solar power to provide for those energy needs over the course of time.

According to the study, Britain’s energy needs could easily be met entirely by the two sources of clean power.  Wind and solar can provide significantly more energy than the highest energy demand forecasted for 2050 and nearly 10 times the current electricity demand. 

Britain currently requires 299 TWh per year.  The Oxford study found that wind and solar could generate as much as 2,896 TWh per year. Furthermore, the researchers stated that these estimates are intentionally conservative, taking into account concerns around land use and the visual impact of installations.

The analysis assumes that offshore wind would produce nearly three-quarters of the energy required.  Onshore wind would contribute about 7%, while taking up only 0.07% of the country’s land.  Utility-scale solar would add about 19% of the power.  The small remainder comes from rooftop solar.  The researchers do point out that the power grid would require significant upgrades to handle all this renewable energy and that there would need to be appropriate quantities of energy storage. 

According to the authors of the study, achieving these results is a question of ambition rather than technical feasibility.  So far, the UK government has not been aggressive in making the transition to renewable energy.

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Wind and solar power could significantly exceed Britain’s energy needs

Photo, posted November 4, 2021, courtesy of Steve Knight via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Record low Antarctic sea ice

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Antarctica’s winter came to a close in September and during that month, the continent reaches its maximum amount of sea ice that grows during the darkest and coldest months.  This year, that maximum occurred on September 10th and turned out to be the lowest on record.

The sea ice around Antarctica reached a maximum extent of 6.5 million square miles according to NASA researchers.  That was nearly 400,000 square miles below the previous record low set in 1986. 

There are several possible causes for the meager growth of Antarctic sea ice this year.  It may be a combination of several factors including El Niño, wind patterns, and warming ocean temperatures.  Recent research indicates that ocean heat is most likely playing an important role in slowing ice growth in the cold season and enhancing ice melting in the warm season.

The record-low ice extent so far this year is a continuation of a downward trend in Antarctic sea ice that has gone on since the ice reached a record high in 2014.  Prior to that year, the ice surrounding the southern continent was actually increasing slightly by about 1% every decade.

Meanwhile, Arctic sea ice reached its minimum extent in September and it was the sixth-lowest level in the satellite record.  Scientists track the seasonal and annual fluctuations of polar sea ice because they shape polar ecosystems and play a significant role in global climate.  Sea ice melting at both poles reinforces global warming because bright sea ice reflects most of the Sun’s energy back to space while open ocean water absorbs 90% of it.

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Antarctic Sea Ice Sees Record Low Growth  

Photo, posted June 30, 2023, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating Sea Farms | Earth Wise

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Researchers at the University of South Australia have designed a self-sustaining solar-driven system that turns seawater into fresh water and grows crops without any involvement.  In theory, such a system could help address the growing problems of freshwater shortages and inadequate food supplies as the world’s population continues to increase.

The system can be described as a vertical floating sea farm.  It is made up of two chambers:  an upper layer similar to a greenhouse and a lower chamber for water harvesting.

Clean water is supplied by an array of solar evaporators that soak up seawater, trap the salts in the evaporator body and, heated by the sun, release clean water vapor into the air which is then condensed on belts that transfer the water into the upper plant growth chamber.

The researchers tested the system by growing broccoli, lettuce and bok choi on seawater surfaces without maintenance or additional clean water irrigation.  The system was powered entirely by solar light.

The design is only a proof-of-concept at this point.   The next step is to scale it up using an array of individual devices to increase plant production. 

The futuristic potential for such technology would be huge farm biodomes floating on the ocean.  The UN estimates that by 2050, nearly 2.5 billion people are likely to experience water shortages while the global supply of water for irrigation is expected to decline by 19%.  Nearly 98% of the world’s water is in the oceans.  Harnessing the sea and the sun to address growing global shortages could be the way to go.

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Floating sea farms: a solution to feed the world and ensure freshwater by 2050

Photo, posted February 11, 2015, courtesy of Ed Dunens via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Why Was the Summer So Hot? | Earth Wise

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Many places around the world have experienced extraordinary heat waves this summer.  The 31 days of high temperatures 110 degrees or more in Phoenix is a prime example but many other places suffered from extreme and relentless heat.  Why did this happen?

The overarching reason is climate change, which has warmed the Earth by 2.2 degrees Fahrenheit since the preindustrial era.  This change on a global level is enough to make heatwaves far more likely.  For example, the concurrent heatwaves in Europe and North America were 1000 times more likely to have occurred because of climate change.

But there hasn’t been a sudden increase in global temperature that would make this summer so much hotter.  Instead, what really has happened is three other factors all came into play at the same time.

The first is the 2022 eruption of Hunga Tonga-Hunga Ha-apai, which is an underwater volcano in the South Pacific.  That eruption did not produce much in the way of planet-cooling aerosols in the atmosphere.  Instead, it vaporized huge amounts of seawater, sending water vapor into the atmosphere, which helps trap heat.

The second is a change in the amount of energy radiating from the sun.  That actually rises and falls a small amount every 11 years.  Currently, it is in the upswing and will reach its next peak in 2025.

Finally, there is the arrival of the El Niño in the Pacific, whose balmy ocean waters radiate heat into the air.

The combination of all these factors when added to the already warming climate is a recipe for temperatures to soar to uncharted highs.  We can expect more heat waves, forest fires, flash floods, and other sorts of extreme weather.

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It’s Not Just Climate Change: Three Other Factors Driving This Summer’s Extreme Heat

Photo, posted February 27, 2017, courtesy of Giuseppe Milo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Missing Antarctic Sea Ice | Earth Wise

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It is summer here in the United States, but it is winter in Antarctica.  Antarctic sea ice is water that forms and melts entirely in the ocean and it has a pattern of growth and reduction that has been monitored by satellites for the past 44 years.  The area of sea ice that surrounds the continent of Antarctica is known as the sea ice ‘extent’ and it had been quite stable for much of those years.

In 2016, the sea ice extent began to decline.  Since then, there have been several record summer lows with both the summers of 2021/22 and 2022/23 setting new minimum records.

This August, the deviation from all previous records intensified.  This winter’s sea ice extent is over 900,000 square miles below the long-term average, an area about the size of Greenland or, for example, Texas and Alaska combined.

Climate models have long predicted that Antarctic sea ice would reduce as a result of global warming but the current change to sea-ice extent is so dramatic that it is difficult to explain.  Sea ice extent is affected by multiple factors including the El Niño Southern Oscillation, the strength of the southern hemisphere jet stream, and regional low-pressure systems.  The warming climate is certainly the overall force that is changing Antarctic sea ice extent over time.

Antarctic sea ice extent is important because it covers a vast area of the dark Southern Sea with a bright white surface that reflects the sun’s energy back into space, helping to reduce temperatures at the pole and protecting glaciers and polar ice sheets. 

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The mystery of the missing Antarctic sea ice

Photo, posted November 7, 2016, courtesy of Rob Oo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating Solar And Hydropower | Earth Wise

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Installing solar panels on the surface of reservoirs is an up-and-coming trend.  The arrays of solar panels produce renewable energy while at the same time shielding significant expanses of water from the sun’s heat, thereby reducing evaporation.  The panels also help to inhibit the growth of algae.

Two recent floating solar installations are demonstrating the synergy between solar power and hydroelectric power.

The Lazer floating solar plant in France comprises over 50,000 solar panels and is capable of producing 30 MW of power.  The reservoir serves a 16.5 MW hydropower plant.  During the summer, the water from Lazer Reservoir is used primarily for crop irrigation and the solar plant supplements power generation as the reservoir water level experiences variations.  This is the first facility of its kind to be installed in France.  The company that built it – the EDF Group – had already built four floating solar power plants in Israel and the US. 

In Colombia, the Aquasol solar project is installed at the 340 MW Urrá hydropower plant.  Its 2,800 solar panels produce enough power to offset the amount of energy it takes to operate the dam.  The floating solar system is designed to withstand water-level fluctuations of up to 120 feet.

Floating solar systems can help keep power flowing when low water levels or other adverse conditions reduce hydroelectric output.  About 60% of the world’s renewable energy comes from hydropower.  Given this fact, there are countless opportunities to deploy floating solar that maximizes zero-emission energy generation as well as diversifying clean energy sources.

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Floating solar and hydropower: A match made in renewable energy heaven

Photo, posted October 25, 2010, courtesy of Martin Abegglen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Renewables In China | Earth Wise

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A couple of years ago, China set an ambitious goal for renewable energy capacity – which includes wind, solar, hydroelectric, and nuclear power – for it to exceed fossil fuel capacity by 2025.  According to a recent report by Reuters, China has hit this goal two years ahead of schedule.  Renewables now make up 50.9% of the country’s power capacity.

The rapid growth in renewable capacity has largely been driven by investments in wind and solar megaprojects in the sparsely populated west of the country that export power to the manufacturing centers in the east.  China’s most recent 5-year plan calls for 570 gigawatts of wind and solar power to be installed over that period, which more than doubles its installed capacity.  The plan makes use of what it called “clean energy bases”, which utilize sandy and rocky deserts, other types of barren lands, and wastelands left behind by coal mining.  The largest clean energy bases make use of vast deserts in Inner Mongolia and Gansu.

One cautionary note is that power capacity refers to the maximum amount of electricity that a power plant can produce under ideal conditions.  Thus, for example, it refers to how much electricity a solar farm can generate at noon on a cloudless day.  So, the new figures from China don’t necessarily reveal how much electricity China is actually drawing from renewables.  In reality, China still gets a great deal of its power from coal.

China is the world’s largest emitter of carbon dioxide – more than twice as much as the United States, albeit from nearly 4 times the population.  The rapid growth of renewables is at least moving that country in the right direction.

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Fossil Fuels Now Account for Less Than Half of China’s Power Capacity

Photo, posted December 2, 2015, courtesy of IBM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Liquid Fuel From Sunshine | Earth Wise

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A key goal of artificial photosynthesis research is to be able to produce a useful liquid fuel using only carbon dioxide, water, and sunlight in a single step.  Such a so-called solar fuel would produce net zero carbon emissions and would be completely renewable.

Bioethanol has long been touted as a green alternative to fossil fuels, since it is made from plants rather than petroleum.  But producing it takes up agricultural land that could be used to grow food instead and there are emissions associated with many aspects of the process by which plant mass becomes fuel.

Researchers from the University of Cambridge in the UK have developed a so-called artificial leaf that produces ethanol or propanol – usable liquid fuels – in a single step.  They developed a copper and palladium-based catalyst that allows the artificial leaf to directly produce multicarbon complex chemicals.  Earlier versions of artificial leaves could make simple chemicals, such as syngas, which would then require additional processing to turn into high-density fuels.

The new device produces liquid fuel from carbon dioxide and water simply by shining sunlight on it.

At present, the artificial leaf is a proof-of-concept device that exhibits only modest efficiency.  The researchers are working to optimize the device’s light absorbers so that they can better make use of sunlight and to optimize the catalyst so that it can convert more of the sunlight into fuel.  In addition, the device needs to be scaled up so that it can produce large volumes of fuel.

All that being said, it is an important step towards people being able to do what plants have been doing for millions of years.

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Driving on sunshine: clean, usable liquid fuels made from solar power

Photo, posted March 23, 2015, courtesy of Astro via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better Zinc Batteries | Earth Wise

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The rapid growth of wind and solar power continues to drive a global quest for new battery technologies that can be used to store the energy generated by these sources when the sun isn’t shining, and the wind isn’t blowing.

For the most part, current battery energy storage systems use lithium-ion batteries – the same sort of batteries found in cellphones and electric vehicles.  There are many other battery chemistries, but they mostly have shortcomings in performance, economy, or longevity. 

Batteries store electricity in the form of chemical energy and chemical reactions convert that energy into electrical energy. Every battery has two electrodes:  the anode, from which electrons flow into external circuits, and the cathode, which receives electrons from the external circuit.  The electrolyte is the chemical medium through which the electrons flow.

One technology that has great potential is zinc-based batteries.  Zinc itself is a metal that is safe and abundant.  Batteries based on it are energy dense. However, zinc batteries have faced the challenge of having a short cycle life.  The batteries end up plating zinc on their anodes and battery performance degrades. 

A team of researchers at Oregon State University and three other universities have recently developed a new electrolyte for zinc batteries that raises the efficiency of the zinc metal anode to nearly 100% – actually slightly better than lithium-ion batteries.

Zinc batteries have a number of potential advantages over lithium-ion.  The new hybrid electrolyte developed by the researchers is non-flammable, cost-effective, and has low environmental impact.  Lithium-ion batteries rely on the supplies of relatively rare metals that are often difficult and environmentally harmful to obtain. 

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Researchers develop electrolyte enabling high efficiency of safe, sustainable zinc batteries

Photo, posted May 13, 2017, courtesy of Jeanne Menjoulet 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

Plastic From Sunlight | Earth Wise

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Photosynthesis is the process that plants use to turn water, carbon dioxide, and energy from sunlight into plant biomass.  It provides humans and much of animal life with food.  Photosynthesis is also nature’s way of reducing the amount of carbon dioxide in the atmosphere.  The CO2 is not directly stored in plants but rather is combined into organic compounds.

Researchers across the globe are trying to find effective ways to mimic photosynthesis.  One version of artificial photosynthesis seeks to take carbon dioxide and combine it into organic compounds that can be used as raw materials for various kinds of manufacturing. 

A research team in Japan has found a way to synthesize fumaric acid from carbon dioxide using sunlight to power the process.  Fumaric acid is a chemical typically synthesized from petroleum and is used as a raw material for making biodegradable plastics such as polybutylene succinate. 

Much of artificial photosynthesis research is aimed at using solar energy to convert carbon dioxide directly into a fuel rather than a raw material.  Such solar fuels can be produced by a variety of means including thermochemical (using the sun’s heat to drive chemical reactions), photochemical (using the sun’s light to drive chemical reactions), and electrochemical (using solar-generated electricity to drive chemical reactions.)   These approaches generally involve the use of specialized catalysts to drive the desired chemical reactions. 

One way or another, what techniques for artificial photosynthesis have in common is trying to imitate what plant life on Earth has been doing for millions of years. 

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Artificial photosynthesis uses sunlight to make biodegradable plastic

Photo, posted June 14, 2017, courtesy of Alex Holyake via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fusion Power And The Climate Crisis | Earth Wise

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In December, the Department of Energy announced that scientists at Lawrence Livermore National Laboratory in California had achieved a breakthrough in nuclear fusion technology.  Fusion is the process by which the sun generates energy.  If we had the means to produce nuclear fusion in a controlled fashion, it would be an almost limitless source of clean energy.

Scientists have been trying to develop controllable fusion since the advent of the hydrogen bomb in the 1950s.  H-Bombs are basically uncontrollable fusion.

There are massive experiments under development around the work seeking the means to create and control fusion.  There are multi-billion-dollar projects such as the ITER tokamak project in southern France, that have been ongoing for decades.  Colossal equipment is required to produce the temperatures of millions of degrees needed to fuse hydrogen atoms into helium atoms.

The Livermore project uses 192 powerful laser beams to vaporize a tiny pellet and provide the energy required to initiate fusion. The breakthrough is that the experiment released more energy than the lasers put in.  This was the first time a fusion experiment produced a net gain of energy.

Is fusion the solution to de-carbonizing the energy system?  Perhaps someday it might be.  However, even the most optimistic fusion researchers believe it will be at least another decade before even the experimental fusion systems around the world can reliably produce energy and the efforts will cost untold billions of dollars. 

The world cannot wait for fusion power to save the day.  The focus must remain on currently available renewable energy technologies if we are to achieve the necessary emission reductions in time to prevent the worst effects of climate change.

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Can Fusion Solve the Climate Crisis?

Photo, posted July 29, 2010, courtesy of Steve Jurvetson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

It Really Is Greenhouse Gases | Earth Wise

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The scientific consensus that human-generated carbon dioxide is changing the climate began to form in the 1980s. 

For a long time, the changes to the climate were simply denied.  After a while, as those changes became increasingly hard to ignore, the argument shifted to the changes being real but not caused by anything people are doing.  The multi-trillion-dollar fossil fuel industry was strongly motivated to focus attention away from the association between carbon dioxide and climate change.

The greenhouse gas effect has been known since the 19th century.  It isn’t just real; it is essential to life on earth.  Without sufficient levels of carbon dioxide in the atmosphere to trap some of the sun’s heat, the earth would be an ice planet incapable of supporting much in the way of life.  But there can be too much of a good thing.

Naysayers continue to grasp at alternative explanations for the warming planet rather than the inconvenient truth.  Some people try to claim that it is the release of heat from all our energy-generating activities -power plants, heaters and air conditioners, vehicles, and so on – that is warming the planet.

That issue has been studied in detail.  Human activity does generate a lot of heat and, technically speaking, that heat does help warm the planet.  However, the sun dumps 10,000 times more heat on the earth than all of human energy production added together.  Just the normal fluctuations in solar energy are 10 times larger than everything we do put together.

What is increasingly warming the planet is not the continuing energy striking the earth; it is primarily the fact that growing levels of greenhouse gases in the atmosphere are trapping more and more of that heat and preventing it from escaping into space.

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Integrating anthropogenic heat flux with global climate models

Photo, posted August 25, 2009, courtesy of Gerald Simmons via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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

Colorful Solar Panels | Earth Wise

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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

Solar-Powered Desalination | Earth Wise

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About two-thirds of humanity is affected by water shortages.  In the developing world, many areas with water shortages also lack dependable sources of electricity.  Given this situation, there is widespread research on using solar heat to desalinate seawater.  To date, many approaches to this face problems with fouling of equipment with salt buildup.  Tackling this issue has proven to add complexity and expense to solar desalination techniques.

A team of researchers from MIT and China has recently developed a solution to the problem of salt accumulation that is more efficient than previous methods and is less expensive as well.

Previous attempts at solar desalination have relied on some sort of wick to draw saline water through the device.  These wicks are vulnerable to salt accumulation and are difficult to clean.  The MIT-Chinese team has developed a wick-free system instead.  It is a layered system with dark material at the top to absorb the sun’s heat, and then a thin layer of water that sits above a perforated layer of plastic material.  That layer sits atop a deep reservoir of salty water such as a tank or pond.  The researchers determined the optimal size for the holes in the perforated plastic.

The 2.5 millimeter holes are large enough to allow for convective circulation between the warmer upper layer of water above the perforated layer and the colder reservoir below.  That circulation naturally draws the salt from the thin layer above down into the much larger body of water below.

The system utilizes low-cost, easy to use materials.  The next step is to scale up the devices into a size that has practical applications.  According to the team, just a one-square-meter system could provide a family’s daily needs for drinking water.

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Solar-powered system offers a route to inexpensive desalination

Photo, posted February 13, 2017, courtesy of Jacob Vanderheyden via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Progress On Perovskite Solar Cells | Earth Wise

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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.

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Space Tourism And The Climate | Earth Wise

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Space tourism is human space travel for recreational purposes.  A few well-known billionaires have taken rocket rides in recent years and at least a dozen companies are at the vanguard of what they are expecting to be a burgeoning industry.  If space tourism truly takes off – pun intended – it could be a serious threat to the climate and the environment.

Black carbon – essentially soot – is emitted when fossil fuels, including rocket fuels, are burned.  Black carbon absorbs light from the sun and releases thermal energy, making it a powerful climate warming agent.  At lower altitudes, black carbon quickly falls from the sky, remaining in the atmosphere for only a matter of days or weeks.

Rockets are another story entirely.  They dump black carbon into the stratosphere as they blast into space, and up there black carbon is 500 times worse for the climate and sticks around for several years.

A detailed study by researchers at University College London looked at the climate impact of present-day space launches compared with the potential massive expansion of launches from a large space tourism industry.

The overall result is that current space launches are not a significant source of emissions, but space launches would become incredibly significant if projections of tourist space flights proved to be true.  Currently, there are roughly 100 space launches a year world-wide.  If that number becomes thousands, the impact on the climate would be substantial.

The same researchers looked at the ozone impact of rocket launches and reached a similar conclusion.  The current impact of spaceflights is not very significant, but a massive increase in launches could have a major impact on atmospheric ozone concentrations.

Space tourism may be exciting, but it also could be very dangerous for the planet.

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Web Links

Space Tourism Poses a Significant ‘Risk to the Climate’

Impact of Rocket Launch and Space Debris Air Pollutant Emissions on Stratospheric Ozone and Global Climate

Photo, posted May 30, 2020, courtesy of Daniel Oberhaus (2020) via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)