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Deconstructing buildings

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An estimated 30 million tons of wood waste from construction and demolition in the U.S. ends up in landfills each year.  A growing number of cities have launched initiatives to reuse the wood instead.  It is a strategy to reduce carbon emissions, cut waste, and shift towards a circular economy.

For a long time, salvaged wood was a niche pursuit by people who valued the fine grain and enduring quality of older wood.  Reclaimed old-growth lumber offers character and strength.  These people pursued construction that uses wood with a story – timber recovered from historic structures, collapsing barns, and other demolished buildings.

Now, there are multiple companies in the business of salvaging wood from buildings.  Cities and businesses are embracing the use of reclaimed materials.   Ordinances in cities like Portland, Oregon, Boulder, Colorado, and San Antonio, Texas require older buildings to be taken apart for repurposing their materials.  Palo Alto, California has banned demolition completely. 

Portland was the first U.S. city to require old residential homes to be deconstructed.  After a decade, contractors have deconstructed more than 650 homes in the city, salvaging 2,000 tons of reusable wood.

Using reclaimed wood in local buildings stores carbon and reduces emissions by avoiding the need to cut new trees, process materials, and ship them long distances.

Deconstructing buildings is not a widely available skill.  Contractors have to be trained on how to dismantle buildings piece by piece.  But there is now a national registry of deconstruction trainers and a network of practitioners.

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Deconstructing Buildings: The Quest for New Life for Old Wood

Photo, posted May 16, 2018, courtesy of Alexandre Prevot via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The coastal squeeze

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Globally, coastal areas are being squeezed between rising seas on one side and human development on the other.  The average distance from the high waterline to the first built-up area with human structures or paved roads is less than 400 yards around the world.  The narrower a coast, the sooner rising sea levels cause problems.

Narrow coasts have reduced ability to defend against storm surges and other weather events.  Construction close to the sea makes coastal areas extra vulnerable.  Narrow coasts are also bad news for biodiversity.  A study by the Royal Netherlands Institute for Sea Research investigated plant diversity in both the Netherlands and the United States.  They found that the wider the coast was, the greater the plant diversity.

In Florida and Georgia, whenever coastal zones reached a couple of kilometers in width, diversity increased rapidly.  In the Netherlands, only coastal areas at least 3.8 kilometers wide reached their maximum plant diversity, but such areas are rare.  Dutch sand dune areas are typically no more than a kilometer wide, leaving plant diversity at no more than half the possible level.

Limited biodiversity in narrow coastal strips can be somewhat boosted by nature management but would benefit much more by spatial planning.  In the Netherlands, a spot called The Sand Motor is where a gigantic amount of sand was deposited off the coast in 2011.  Since then, natural forces have spread it along the coast.  Such coastal expansion could increase biodiversity.  Biodiversity is not a luxury.  It makes for a better future for coastal defense, a healthy drinking water supply, and a better human food supply.

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Coastal squeeze is bad for biodiversity, and for us!

Photo, posted June 21, 2017, courtesy of Mark Bias via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Coexisting birds and solar energy

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Floating photovoltaic systems – known as floatovoltaics – are becoming increasingly popular.  These are arrays of solar panels installed over artificial water bodies such as irrigation ponds, wastewater treatment plants, and reservoirs.  These projects maximize the space for producing clean energy while not taking up natural lands.

Wherever there are bodies of water, there are waterbirds.  A recent study by researchers at the University of California, Davis looked at the potential impact of floating solar projects on birds and other wildlife. 

Birds face many threats from habitat loss, climate change, pollution, and disease.  Many bird populations are in decline.  So, it is important to consider the effects of floating solar projects on birds. 

The researchers have observed birds resting on floating solar structures before dawn, birds jockeying for favorable sites on the structures, and some nesting under the panels.  These are positive interactions.  On the other hand, it is possible that pollutants could be released or leached from floating solar infrastructure.  Such risks must be mitigated.

Floating solar on irrigation ponds and reservoirs can reduce evaporation and reduce algae growth, which benefits both humans and wildlife.

The researchers will continue to monitor bird behavior at floating solar installations using expertise in ecology and energy system science to identify risks and solution pathways so that negative impacts are avoided, and potential ecological benefits are realized.  It is important that as floating solar continues to become more popular, it and waterbirds can coexist.

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Helping Birds and Floating Solar Energy Coexist

Photo, posted February 28, 2019, courtesy of Renee Grayson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildlife crossings

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Every year, there are one to two million collisions between motor vehicles and large animals in the U.S.  About 200 people are killed annually.  Counting smaller vertebrates, around a million animals are killed by vehicles each day.  Research has shown that global warming is triggering widespread species redistribution.  As a result, more and more animals are on the move, changing their habitats to escape warming temperatures and climate extremes.

This situation has created renewed interest in creating wildlife crossings.  These are various kinds of structures that allow animals to traverse human-made barriers like highways.  They include such things as a grassy overpass that allows pronghorn to run across a highway in Wyoming and a long underpass that allows tigers to scamper beneath a highway in India.

In the U.S., there are more than 1,000 wildlife crossings and there are more being built all the time.  Data shows that they are highly effective.  A study of wildlife crossings on Highway 9 through the Blue River Valley in Colorado found that they reduced wildlife-vehicle collisions by nearly 90%. 

Wildlife crossing structures can be expensive to build, costing between $500,000 and $6 million, but research has shown that the money saved by avoiding crashes can recoup these costs in just a few years along with the fact that they potentially save lives.  Federal funding is largely distributed based on areas with the highest number of wildlife-vehicle collisions, which is crucial for addressing public safety issues.  However, a recent study suggests that future proposals need to incorporate climate-driven changes in animal behavior and habitat.

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As Climate Changes Fuels Animal Movement, Will These Structures Still Help Species Cross the Road?

Photo, posted April 5, 2017, courtesy of Jeffrey Beall 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

Harvesting Fresh Water From Ocean Air | Earth Wise

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Roughly three-quarters of the world population has access to a safely managed water source.  That means that one-in-four people do not have access to safe drinking water.  Even in the wealthy United States, persistent drought in the west is creating problems in places like Phoenix, Arizona.

Water is plentiful on Earth but more than 99% of it is unusable by humans and many other living things because it is saline, frozen, or inaccessible.  Only about 0.3% of our fresh water is found in the surface water of lakes, rivers, and swamps.

There is an almost limitless supply of fresh water in the form of water vapor above the oceans, but this source is untapped.  Researchers at the University of Illinois have been evaluating the feasibility of a hypothetical structure capable of capturing water vapor from above the ocean and condensing it into fresh water.

Existing ways to obtain fresh water like wastewater recycling, cloud seeding, and desalination have met only limited success and present various problems with regard to cost, environmental impact, and scalability.

The researchers have proposed hypothetical large offshore structures measuring 700 feet by 300 feet to capture water vapor that is continually evaporating from the ocean in subtropical regions.   Their modeling concluded that such structures could provide fresh water for large population centers in the subtropics.  Furthermore, climate projections show that the amount of water vapor over the oceans will only increase over time, providing even more fresh water supply.

This is only a theoretical study at this point, but the researchers believe it opens the door for novel infrastructure investments that could address global water scarcity.

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Researchers propose new structures to harvest untapped source of fresh water

Photo, posted June 28, 2009, courtesy of Nicolas Raymond via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

History Emerges In European Drought | Earth Wise

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During the summer, much of Europe faced a string of extreme heat waves and a devastating drought.  As a result, many reservoirs and rivers have shrunk back to reveal historical structures and relics that, in some cases, date back thousands of years.  Once-submerged villages, ships, and bridges have re-emerged this year.

In northwest Spain, a former village called Aceredo has reappeared after having been submerged 30 years ago when a hydropower dam flooded the valley where it was located.  Elsewhere in Spain, the Dolmen of Guadalperal, a 4000-5000-year-old stone monument often called the Spanish Stonehedge, has risen from a drought-stricken dam west of Madrid

In Italy, which is suffering from its worst drought in 70 years, the ruins of a bridge from the time of Nero are now visible in the Tiber River.   One of Germany’s largest reservoirs, the Edersee, has shrunk back so much that parts of Berich, a village that was flooded in 1914, can be seen.  In Serbia, water levels in the Danube River are so low that more than a dozen sunken Nazi boats from World War II have been exposed in the town of Prahovo.   In Northern England, the lower water levels of the Batings Reservoir have uncovered an ancient packhorse bridge.

The shrinking of riverbeds and reservoirs across Europe has attracted a great deal of attention, probably more than many other effects of the increasing number of extreme weather events because it is so visual.  But the frequency of extreme heat and drought is only likely to increase over time.

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Europe’s Shrinking Waterways Reveal Treasures, and Experts Are Worried

Photo, posted July 13, 2017, courtesy of Marco Brandstetter via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon Storage In Harvested Wood | Earth Wise

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Trees are an exceedingly important carbon sink on our planet.  For this reason, deforestation is a major contributor to climate change.  But when trees are harvested for wood products like lumber, much of the carbon in that wood continues to be stored.  Even when a wood product is discarded at the end of its useful life, it can keep storing carbon.

Over 90% of new single-family homes in the U.S. are built with wood.  Each year, about 400,000 homes, apartment buildings, and other housing units are lost to floods and other natural disasters.  Others fall apart from decay or are torn down to be replaced with newer structures.  Given how much carbon is stored in houses, it is important to understand what the future trajectory of residential structures will be.

A new study by the USDA Forest Service published in the journal PLOS ONE looks at the future of harvested wood products in residential structures.  According to the study, wood products in these structures will continue to increase the country’s carbon storage for the next 50 years. 

Even after residential structures reach the end of their useful life and much of the materials end up in landfills (which is typical in this country), the wood products do not immediately release their carbon.  It may take decades for that to happen.

The study looked at various scenarios for future home construction.  Although housing starts are projected to decline in the future, residential housing and the need to maintain existing structures are projected to continue to increase carbon storage in wood products for the next several decades.

The role of trees as a carbon sink does not end when they are harvested for their wood.

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Carbon Storage in Harvested Wood Products

Photo, posted January 27, 2022, courtesy of Luke McKernan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating Offshore Wind | Earth Wise

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According to a new report by the Global Wind Energy Council, floating offshore wind technology is on track to grow from a miniscule market to a substantial contribution to the world’s energy supply over the next decade.  Furthermore, the United States represents one of the countries with the greatest potential.

Wind power is stronger and steadier in the ocean than on land, so the use of offshore wind is rapidly expanding.  However, because most installations are based on fixed structures attached to the sea bottom, they cannot be installed in very deep or complex seabed locations.

Floating offshore wind is based on structures that are anchored to the seabed only by means of flexible anchors, chains, or steel cables.  Apart from making it feasible to place wind turbines in deeper and more distant locations, floating turbines and platforms can also be built and assembled on land and then towed to the offshore installation site.

The floating offshore wind industry is currently in a pre-commercial phase but has great potential.  Many offshore locations with great potential in terms of their wind resources are unsuitable for conventional installations either because of the depth of the seabed or its complex structure.  This is particularly true of the waters off the coasts of California, Oregon, and the Gulf Coast, which otherwise offer excellent wind resources.

There are many issues to deal with in expanding the use of floating offshore wind, including transporting the power to shore and the ability of the local power grids to handle the incoming power.  On the other hand, distantly placed floating offshore wind reduces environmental concerns and eliminates issues associated with the visual impact of wind farms for coastal residents.

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What’s the potential of floating offshore wind?

Photo, posted May 10, 2015, courtesy of Olin Gilbert via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Artificial Aquatic Polyps | Earth Wise

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Corals are often mistaken for rocks because of their hardened surfaces.  And, since they attach or “take root” to the sea floor, they are often mistaken for plants.  But unlike rocks, corals are alive.  And unlike plants, corals do not make their own food.  Corals are actually animals. 

Most of these structures that we call “coral” are made up of hundreds to thousands of tiny coral creatures called polyps.  A coral polyp, which is often no thicker than a nickel, has a saclike body and mouth that is encircled by stinging tentacles.  Polyps are responsible for a host of ecosystem services, including nourishing corals, and aiding coral survival by generating self-made currents through the motion of their soft bodies. 

Inspired by these marine organisms, researchers from the University of Warwick in the UK and Eindhoven University of Technology in the Netherlands have collaborated to develop an artificial aquatic polyp capable of removing contaminants from water.  The 1 square centimeter wireless robot polyp can attract, grasp, and release objects, moving under the influence of a magnetic field and whose “tentacles” are triggered by light. 

The next step for the researchers is to see if the technology can be successfully scaled up from laboratory to pilot scale.  In order for that to happen, the team has to design an array of artificial polyps capable of working harmoniously together.   

Corals are an incredibly important part of ocean ecosystems.  And while it remains to be seen how much value artificial polyps can achieve in future applications, it serves as another example of scientists emulating nature to create more sustainable designs. 

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Aquatic robots can remove contaminant particles from water

An artificial aquatic polyp that wirelessly attracts, grasps, and releases objects

Photo, posted April 14, 2011, courtesy of Derek Keats via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Oil Platforms And Fish | Earth Wise

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It is well-known that offshore oil platforms become major habitats for fish.  Their support structures rise hundreds of feet through the water column and basically create a prefabricated reef for marine life.   Many of these platforms will soon be decommissioned and government agencies are considering the consequences to undersea life when this happens.

Researchers at the University of California Santa Barbara have looked at how various decommissioning scenarios would affect undersea ecosystems. They found that completely removing a platform could reduce fish biomass by an average of 95%.  In contrast, removing just the top part of the rig could keep losses to around 10%.

California is looking at several possibilities for decommissioning 27 oil platforms off of its coast.  The three options are:  leave the platform in place, remove all of it, or remove just the top part of it.  Each option entails its own economic and ecological consequences.

The research team studied the size and composition of fish communities at 24 platforms and created models for each of the decommissioning scenarios.  The partial removal approach involved stripping away all structures within 26 meters of the surface.  This number would eliminate the need for a lighted buoy where the support structure remained according to U.S. Coast Guard guidelines.

For the 24 structures studied, leaving them entirely in place would support over 29,000 kilograms of fish biomass.  Removing just the top 26 meters would support nearly 28,000 kilograms.  Removing the platforms entirely would support only 500 kilograms of fish biomass.

As California weighs how to decommission its oil platforms, studies like this will be critical to making informed decisions.

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Oil Platforms’ Fishy Future

Photo, posted June 4, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Turning Dead Trees Into Biomass Energy | Earth Wise

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California has suffered from numerous large wildfires in recent years.  The two largest in the past century took place in 2017 and 2018, and just these two alone burned nearly 750,000 acres, destroyed over 1,200 structures, and killed 24 people.

Apart from the fires, drought, the warming climate, and bark-beetle infestations have killed 147 million California trees since 2013, most of them along the spine of the Sierra mountains.  These dead trees represent a significant danger in forthcoming fire seasons as they threaten to burn with enormous intensity.

There are now biomass projects in California that thin trees in overcrowded forests and remove dead and diseased trees and turn them into wood chips to supply community biomass facilities that burn them to produce heat and electricity.

Proponents say these projects help rebuild rural communities by creating jobs, while at the same time reducing fire risk. 

There are critics of these programs who claim that they are damaging and destroying ecosystems.    They also point out that burning forest fuels emits 50% more carbon than burning coal and three times as much as burning natural gas.  This is true of biomass in general but is mitigated by the fact that it in principle the carbon can be recaptured by new forest growth.

However, the dominant argument about emissions is that wildfires emit far more carbon dioxide than biomass plants, or much of anything else, for that matter.  In 2018 alone, California wildfires released 50% more carbon dioxide than California’s entire industrial sector.  So, reducing the extent of wildfires is a big deal for many reasons.

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In California, A Push Grows to Turn Dead Trees into Biomass Energy

Photo, posted August 24, 2016, courtesy of the USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Kind Of Coral Nursery

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Coral reefs around the world are struggling from warming waters and increasing ocean acidification driven by excess carbon dioxide.  Many of the world’s greatest reefs – such as Australia’s Great Barrier Reef – have seen steep declines over the past decade.

But apart from the global environmental threat, reefs also are often damaged by various marine accidents such as ships grounding on them.   Such events can severely damage a reef and scatter countless small coral fragments onto the seafloor.  These small pieces of coral are not actually dead; they can continue on with their lives if they are relocated to a suitable environment such as a coral nursery.

Coral nurseries are generally small installations that allow coral fragments – typically pieces about 4 inches in length – to recover from their reef breaking up and to grow until they are large enough for conservation managers to replant them into reefs that need them.  This strategy works well in places where corals grow relatively quickly – such as Florida and the Caribbean – but not as well in places where coral grows more slowly, such as Hawaii.

Recently, coral experts at the National Oceanic and Atmospheric Administration working with mechanical engineering students at the University of Hawaii have developed a new type of coral nursery that can save fully formed coral colonies as opposed to small coral fragments.

The nurseries are large, carefully designed structures that can be loaded up with corals that have become detached from their reefs.  Some of these new structures were installed in the waters of Oahu in the summer of 2018 and were populated with corals.  The relocated corals, which would have otherwise died, are now recovering nicely in their new coral daycare centers and will soon be replanted back into the reef.

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NOAA Develops A New Type of Coral Nursery

Photo, posted July 29, 2010, courtesy of Kyle Taylor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Trees And The Future Of Cities

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The shade of a single tree is a welcome source of relief on a hot summer day.  But even a relatively small patch of woods can have a profound cooling effect.  A new study at the University of Wisconsin-Madison looks at the role trees play in keeping towns and cities cool.

According to the study, the right amount of tree cover can lower daytime temperatures in the summer by as much as 10 degrees.  The effects are noticeable from neighborhood to neighborhood and even on a block-by-block basis.

Cities are well-known to be hot spots due to the urban heat islanding effect.  Using trees to keep temperatures more comfortable in cities can make a big difference for the people who live and work there.

The man-made structures of cities – roads, sidewalks, and buildings – absorb heat from the sun during the day and slowly release it at night.  Trees, on the other hand, not only shade those structures from the sun, but they also transpire -or release water in the air through their leaves – which helps to cool things down.

According to the study, to get maximum cooling benefits, tree canopies must exceed forty percent, meaning that city blocks need to be nearly halfway covered by tree branches and leaves.  To get the biggest bang for the buck, cities should start planting more trees in areas that are already near the forty percent threshold.  But

trees can’t just be in parks.  They need to be in places where people are active.

If we want the places where we live to be more comfortable and resilient in a warming world, we need to plant more trees.

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Study suggests trees are crucial to the future of our cities

Photo, posted May 26, 2012, courtesy of Mislav Marohnic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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