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Sand mining and the environment

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Sand mining is the world’s largest mining endeavor.  It is responsible for 85% of all mineral extraction.  It is also the least regulated, possibly the most corrupt, and likely the most environmentally destructive.  Sand is the second-most exploited natural resource in the world after water.  Its global use has tripled in the past two decades.  More than 50 billion tons of sand is extracted from the environment each year.

Sand plays a critical role in much of human development around the world.  It is a key ingredient of concrete, asphalt, glass, and electronics.  It is relatively cheap and relatively easy to extract.  But we use enormous amounts of it.

Sand mining is a major threat to rivers and marine ecosystems.  It is linked to coastal erosion, habitat destruction, the spread of invasive species, and damage to fisheries. 

The harm from sand mining is only beginning to attract widespread attention.  A recent study by an international group of scientists published in the journal One Earth identifies        threats posed by sand mining.  Sand extraction in marine environments remains largely overlooked, despite sand and sediment dredging being the second most widespread human activity in coastal areas after fishing.

Sand is generally seen as an inert, abundant material, but it is an essential resource that shapes coastal and marine ecosystems, protects shorelines, and sustains both ecosystems and coastal communities.  Sand extraction near populated coastlines is particularly problematic as climate change makes coastlines increasingly fragile.

Like all other resources on our planet, even sand cannot be taken for granted.  It must be responsibly managed.

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The rising tide of sand mining: a growing threat to marine life

Photo, posted February 7, 2013, courtesy of Pamela Spaugy / U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Storing carbon in buildings

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According to a new study by researchers at the University of California, Davis and Stanford University, construction materials used in buildings have the potential to lock away billions of tons of carbon dioxide.  The study, published in Science, shows that storing CO2 in buildings could be a major contributor to efforts to reduce greenhouse gas emissions.

Overall efforts in carbon sequestration take carbon dioxide – either as it’s being produced or once it’s already in the atmosphere – and store it away.  Storing it might involve injecting it into underground caverns or deep in the ocean.  Alternatively, storing it might involve converting it into a stable form using chemical reactions.  These various strategies involve both practical challenges and potential environmental risks.

The new study suggests that many materials that are already produced in large quantities have the potential to store carbon dioxide.  These include concrete, asphalt, plastics, wood, and brick.  More than 30 billion tons of these materials are produced worldwide every year.

Ways to accomplish carbon storage include adding biochar into concrete, using artificial rocks loaded with carbon as concrete and asphalt aggregates, plastic and asphalt binders based on biomass instead of petroleum, and including biomass fiber into bricks. 

The largest potential is using carbonated aggregates to make concrete.  Concrete is by far the world’s most popular building material with more than 20 billion tons being produced each year.

The feedstocks for these ways to store carbon in building materials are mostly low-value waste materials, so the economics of implementing these carbon sequestering strategies are likely to be quite favorable.

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Storing Carbon in Buildings Could Help Address Climate Change

Photo, posted October 19, 2022, courtesy of Alexandre Prevot via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Planting trees in Europe

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Planting lots of trees is one of many strategies being pursued to combat climate change.  Trees are storehouses of carbon from the atmosphere and planting more of them helps remove carbon dioxide.  But trees do more than that.  Trees are natural air conditioners in cities.

Trees significantly cool urban environments by providing shade and via a process called evapotranspiration by which they release water vapor into the air, which provides cooling.  This helps mitigate the urban heat island effect. Areas under trees in cities can be as much as 25 degrees cooler than in unshaded areas covered in asphalt.

The city of Paris has laid out a plan to help the city prepare for increasing amounts of extreme heat.  The goal is to replace 60,000 parking spaces across the city with trees by the end of this decade.  The plan to rip up parking spaces is part of a greater aim to create more than 700 acres of green space by 2030.  The Paris plan also includes creating more car-free zones and installing reflective roofs on 1,000 public buildings.  Nearly 80% of the buildings in Paris have zinc roofs – an affordable, corrosion-resistant and pretty much inflammable innovation of the 19th century.  However, these roofs can heat up to 194 degrees on a summer day, transferring heat into largely uninsulated top-floor garrets below.

Elsewhere in Europe, Danish lawmakers have agreed on a plan to rewild 10% of the country’s farmland and plant one billion trees.   According to the Danish government, this plan would bring about the biggest change to the Danish landscape in over 100 years.

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To Cope with Extreme Heat, Paris Will Swap Parking Spaces for Trees

Photo, posted April 11, 2014, courtesy of Val H. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cooling cities

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As the climate warms, city dwellers tend to suffer from extreme heat more than people in rural areas because of the urban heat island effect. Extensive surfaces of man-made materials like concrete, asphalt, and brick absorb the sun’s energy and lead to temperatures well above those in the surrounding countryside.

Cities can take countermeasures that include creating urban green spaces full of plants that cool the surrounding air and the use of cool roofs that reflect the sun’s energy back into space.  Local governments in many cities provide incentives for planting more trees.  But more could be accomplished by encouraging the use of cool roofs.

The heat island effect has been well-known for a long time, but scientists are only recently learning what interventions are most effective. A recent study modeled two days of extreme heat in London in 2018 and compared the potential effects of cool roofs, green roofs, roof-top solar panels, and ground level vegetation. They found that cool roofs are the most effective way to lower temperatures and would have reduced London temperatures by 2 degrees on average and as much as 3.6 degrees in some places.

Cool roofs are created by swapping out dark, heat-absorbing roofing materials with reflective materials or simply by painting roofs white. Los Angeles is the first major city to require that all new residential construction includes a cool roof. 

Apart from the effectiveness of passive cooling techniques, using them also reduces the reliance upon air conditioning to protect people from heat.  Air conditioners themselves contribute considerable amounts of heat to urban environments.

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The surprisingly simple way cities could save people from extreme heat

Photo, posted February 21, 2024, courtesy of Warren LeMay via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Seashells inspire better concrete

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Mother of pearl – also known as nacre – is a natural material found in certain seashells such as those of oysters and abalone.  On the microscopic level, it consists of hexagonal tablets of the hard mineral aragonite glued together by a soft biopolymer.  The aragonite gives nacre its strength, and the biopolymer adds flexibility and crack resistance. 

Scientists at Princeton University have developed innovative composite materials inspired by nacre by utilizing conventional construction materials like Portland cement paste combined with a limited amount of polymer.  The new material consists of alternating layers of cement paste sheets with the highly stretchable polymer polyvinyl siloxane.

The materials were subjected to bending tests to evaluate crack resistance or fracture toughness.  Three different versions of the material were tested that used different ways of interposing the polymer layers.  The new materials were compared with similar structures composed entirely of cement.

The concrete-only samples were brittle, breaking suddenly and completely upon reaching their failure point.  The samples with alternating cement and polymer layers demonstrated increased ductility and resistance to cracking. 

By fully mimicking the structure of nacre – using completely separated hexagonal cement tablets – the researchers demonstrated materials with 19 times the ductility and 17 times the fracture toughness of cement while retaining nearly the same strength as solid cement samples.

Engineered materials inspired by nature could eventually help increase the durability of a wide range of brittle ceramic materials, from concrete to porcelain.

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From seashells to cement, nature inspires tougher building material

Photo, posted January 2, 2016, courtesy of Yantra via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Recycling cement

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Concrete is the second-most-used material on the planet.  Only water is used more.  Producing concrete is responsible for 7.5% of human-produced carbon dioxide emissions.  So, finding a cost-effective way to reduce these emissions is a major challenge in the face of ever-growing global demand for concrete.

Researchers at Cambridge University have found that used cement is an effective substitute for lime flux, which is an essential material used in steel recycling that results in a waste product called slag.  When lime is replaced with used cement, the end product instead is recycled cement that can be used to make new concrete.

The process does not add any significant costs to concrete or steel production and significantly reduces the emissions associated with both.

Concrete is made from sand, gravel, water, and cement.  Cement is made by a process called clinkering, in which limestone and other materials are heated to 2,600 degrees Fahrenheit.  The process converts the materials into cement but releases large amounts of CO2 as limestone decarbonates into lime. 

Cambridge researchers found that using cement clinker and iron oxide instead of lime works well in steel recycling.  Crushing old concrete and taking out the sand and stone results in a cement that is reactivated by the recycling furnace to produce a material with excellent properties. 

Recent tests by the Materials Processing Institute showed that recycled cement can be produced at scale in an electric arc furnace.  Ultimately, this method could produce zero emission cement if the electricity for the furnace comes from renewable sources.

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Cement recycling method could help solve one of the world’s biggest climate challenges

Photo, posted July 18, 2011, courtesy of Kenta Mabuchi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Floating cities

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About 40% of the world‘s population lives in coastal regions.  People really like ocean-front property.  But worldwide, rising sea levels mean that more and more people want to live on land that may someday be swallowed up by the sea.

One possible solution to the problem is to build cities on top of the water.  It sounds pretty futuristic and impractical, but it is starting to happen.  There have long been floating communities in places like the Netherlands, but these are for the most part clusters of houseboats moored close together.

But there are far more ambitious projects underway.  The Maldives Floating City, already under construction, will eventually have 5,000 houses located in a lagoon that is a 15-minute boat ride from the capital city of Male.  The housing units will be tethered to the lagoon floor and linked together. 

A new project, located off Busan, South Korea, will combine high and low technology to create a large-scale, on-water town, that can house more than 10,000 people.

The town will be built on enormous concrete platforms suspended on the water.  The platforms float because they are rounded hexagonal boxes that are buoyed up by Archimedes’’ principle.  They can’t sink.  Such structures will attract marine life, providing places for oysters and mussels, for example, to grow. 

The initial development will cover 15 acres and the infrastructure will handle power, water, waste, and even some food.  The goal is even to produce enough energy to provide some to the nearby community.  A bridge will link the community to the land.

The project is scheduled to be completed in 2028.  Future expansion could end up housing 150,000 people.

Floating cities could soon no longer be exotic or futuristic.

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Are Floating Cities the Solution to Rising Seas?

Photo, posted June 5, 2012, courtesy of Raymond Bucko via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Self-heating concrete

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States in the colder parts of the country spend an estimated $2.3 billion a year on snow and ice removal as well as untold millions on repairing roadways damaged by winter weather.  Researchers at Drexel University have been researching a way to extend the service life of concrete surfaces like roadways and to help them maintain a surface temperature above freezing during the winter.

Preventing freezing and thawing as temperatures go up and down and reducing the amount of plowing and salting is a desirable goal.  The Drexel team has developed a cold-weather-resilient concrete mix that is capable of melting snow on its own using only the thermal energy in the environment and not requiring salt, shoveling, or heating systems.

The system uses low-temperature liquid paraffin that turns from its room-temperature liquid state into a solid when temperatures go down.  Incorporating the liquid paraffin into concrete triggers heating when temperatures drop due to the energy released by the phase change.

Tests on slabs of the concrete on the Drexel campus over the past two years recorded 32 freeze-thaw events.  The special slabs maintained a surface temperature between 42 and 55 degrees for up to 10 hours when air temperatures dipped below freezing.

The heating is enough to melt a couple of inches of snow at a rate of a quarter inch an hour.  It’s not enough to melt a heavy snow event before plows are needed, but it can help deice road surfaces and increase transportation safety.  And simply preventing the surface from freezing, thawing, and refreezing can go a long way towards preventing deterioration.  It is promising research toward reducing an ongoing problem in colder climates.

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Drexel’s Self-Heating Concrete Is One Step Closer to Clearing Sidewalks Without Shoveling or Salting

Photo, posted March 16, 2024, courtesy of Ajay Suresh via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

How to make cities cooler

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In cities, the air, surface, and soil temperatures are almost always warmer than in rural areas. This is known as the urban heat island effect.  Urban heat islands occur when cities replace natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat.

Urban planners around the world have been researching ways to reduce the effects of heat in cities.  For example, trees, green roofs, and vegetation can help reduce urban heat island effects by shading building surfaces, deflecting radiation from the sun, and releasing moisture into the atmosphere.

A new study led by researchers from the University of Surrey in the U.K. has analyzed how well various green spaces and waterways are able to cool down cities.  The study, which was recently published in the journal The Innovation, found that wetlands, parks, and even botanical gardens are among the best ways to keep cities cool.   

In fact, the researchers found that botanical gardens can cool city air by a whopping 9°F during heatwaves on average.  Wetlands can cool city air by 8.5°F on average, followed by rain gardens at 8.1°F, green walls at 7.4°F, street trees at 6.8°F, city farms at 6.3°F, city parks at 5.8°F, and reservoirs and playgrounds at 5.2°F. 

The researchers also found that cities can unlock even greater benefits by connecting green spaces into green corridors.  Greening projects can also help remove carbon emissions and prevent flooding.

The research team hopes its findings will help urban planners design more resilient cities. 

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Wetlands, parks and even botanical gardens among the best ways to cool cities during heatwaves

Photo, posted April 25, 2022, courtesy of Catherine Poh Huay Tan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sponging up a river

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During the first week of February, an atmospheric river dumped enormous amounts of rain on Southern California.  Over the course of four days, Los Angeles received 9 inches of rain.  The average annual rainfall in the city is only 14 inches.

But Los Angeles was not the site of a flooding disaster because the city has spent years preparing for this type of deluge by becoming a “sponge city.”   By installing lots of green spaces and shallow basins with porous soil, Los Angeles was able to soak up 8.6 billion gallons of water during the storm, enough to meet the water needs of 100,000 people for a year.

Cities covered with impermeable concrete sidewalks and paved areas make storm-related flooding worse because they are unable to absorb water.  Instead, the water flows into drains and overwhelms infrastructure.

Natural materials like dirt and plants take in water from storms and can filter it into underground aquifer that cities can then tap into, especially during droughts.  Adding green spaces to cities has many other benefits beyond the ability to absorb large amounts of rainwater.

The so-called sponge-city movement is catching on in many other places.  Philadelphia is revamping its water systems in a 25-year project that includes green spaces to absorb stormwater runoff.  In China, the government has spent more than a decade adding spongy elements to dozens of cities around the country.

Sponge cities are part of a broader effort to combine modern engineering techniques with natural systems.  This is known as green-gray infrastructure.  Nature knows what it is doing when it comes to flood control as well as to pollution control.

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‘Spongy’ LA Soaked Up Tons of Water From Atmospheric River

Photo, posted December 28, 2011, courtesy of Ron Reiring via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cleaner And Greener Steel | Earth Wise

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Producing construction materials like concrete and steel is a major contributor to greenhouse gas emissions.  Between 7 and 8% of emissions are due to steelmaking alone, which has been done pretty much the same way for more than a century.

Iron ore is smelted with high-carbon fuel and is turned into so-called pig iron in a blast furnace, which creates the key raw material for the steel industry.  The process uses huge amounts of energy (still often generated by burning fossil fuels) and releases carbon dioxide as a byproduct. 

The Department of Energy is sponsoring 40 projects at universities, national laboratories and companies in 21 states aimed at reducing industrial carbon pollution.  Ten of those projects are focused on decarbonizing iron and steel. These initiatives are part of the overall effort to move the nation towards a net-zero emissions economy by 2050.

A team headed by Case Western Reserve University that includes Lawrence Livermore National Laboratory, the University of Arizona, and steel company Cleveland-Cliffs Inc. has developed a promising new zero-carbon, electrochemical process for producing steel.

The process is a novel molten salt electrolysis method that is low-cost, capable of achieving high rates, and uses environmentally benign chemicals.  The process does not use carbon at all.  Using molten salts, electrochemistry can be performed at moderately high temperatures rather than the temperatures of nearly 3000 degrees Fahrenheit used for conventional steelmaking.  The goal is to enable steel production that is both economically viable at an industrial scale and that is environmentally sustainable.

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Case Western Reserve leading research to develop zero-carbon, electrochemical process to produce iron metal as part of U.S. Department of Energy effort

Photo, posted January 11, 2017, courtesy of Kevin Casey Fleming via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

New York Is Sinking | Earth Wise

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The rising seas represent a threat to coastal cities across the globe.  Increasing that threat is the fact that most global cities are slowly sinking as the earth beneath them settles and groundwater is removed.   Another factor that has seldom been considered is that in major metropolises, the weight of large, concrete-and-steel skyscrapers may be hastening the sinking.

A new study by the U.S. Geological Survey published in the journal Earth’s Future estimated the weight of every building in New York City – 1.085 million of them – which they determined to add up to 1.68 trillion pounds – and estimated the downward force of those structures across the city.

The study found that buildings have a greater effect in areas that are rich in clay compared with those areas where sand or bedrock predominate.  The softer the soil, the more compression there is from buildings.  It wasn’t a mistake to build large buildings in New York, but it is important to understand that doing so pushes down the ground more and more.

The study determined that New York is sinking by around 1 to 2 millimeters each year, although some areas are sinking much faster.  The researchers say that cities must plan for future sinking, which will exacerbate the impact of rising seas. Sea levels are rising 1 to 2 millimeter each year, so the subsidence caused by the weight of buildings is equivalent to moving a year ahead in time with regard to rising ocean levels.  This is not a cause for immediate panic, but it is important to understand that this ongoing process only increases the risk of inundation from flooding.

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New York City Sinking Under Weight of Skyscrapers

Photo, posted January 29, 2016, courtesy of Always Shooting via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon-Negative Concrete | Earth Wise

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Concrete is a mainstay of modern civilization.  The world produces more than 4 billion tons of it each year and the process requires high temperatures, mostly obtained by burning fossil fuels.  The chemical reactions that produce concrete also produce large amounts of carbon dioxide.  In all, cement production is responsible for about 8% of total global carbon emissions by human activities.

This situation is the impetus for a wide range of research activities aimed at reducing the environmental impact of concrete production.  Researchers at Washington State University have recently developed a way of making carbon-negative concrete: a recipe for concrete that absorbs large amounts of carbon dioxide.

There have been attempts in the past to add biochar to concrete.  Biochar is a type of charcoal made from organic waste that sucks up carbon dioxide from the air.  In earlier attempts, even adding 3% of biochar would dramatically reduce the strength of the concrete.

The WSU researchers found that treating biochar with concrete washout wastewater makes it possible to add much more biochar to concrete without reducing its strength.  Mixing it with biochar adds calcium, which induces the formation of the mineral calcite, which in turn strengthens the concrete.

The researchers were able to add up to 30% biochar to their cement mixture.  Within a month, the resultant concrete was comparable in strength to ordinary concrete.  But at the same time, the biochar was able to absorb up to 23% of its weight in carbon dioxide from the air.  The new concrete is potentially the most environmentally friendly concrete ever developed.

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Researchers develop carbon-negative concrete

Photo, posted January 31, 2012, courtesy of Michael J. Nevins / U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Concrete And Carbon | Earth Wise

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After water, concrete is the world’s second most consumed material.  It is the cornerstone of modern infrastructure.  Its production accounts for 8% of global carbon dioxide emissions.  The carbon dioxide is a result of chemical reactions in its manufacture and from the energy required to fuel the reactions.

About half of the emissions associated with concrete come from burning fossil fuels to heat up the mixture of limestone and clay that ultimately becomes ordinary Portland cement.  These emissions could eventually be eliminated by using renewable-generated electricity to provide the necessary heat.  However, the other half of the emissions is inherent in the chemical process.

When the minerals are heated to temperatures above 2500 degrees Fahrenheit, a chemical reaction occurs producing a substance called clinker (which is mostly calcium silicates) and carbon dioxide.  The carbon dioxide escapes into the air.

Portland cement is then mixed with water, sand, and gravel to produce concrete.  The concrete is somewhat alkaline and naturally absorbs carbon dioxide albeit slowly.  Over time, these reactions weaken the concrete and corrode reinforcing rebar.

Researchers at MIT have discovered that the simple addition of sodium bicarbonate (aka baking soda) to the concrete mixture accelerates the early-stage mineralization of carbon dioxide, enough to make a real dent in concrete’s carbon footprint.  In addition, the resulting concrete sets much more quickly.  It forms a new composite phase that doubles the mechanical performance of early-stage concrete.

The goal is to provide much greener, and possibly even carbon-negative construction materials, turning concrete from being a problem to part of a solution.

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New additives could turn concrete into an effective carbon sink

Photo, posted April 4, 2009, courtesy of PSNH via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Timber Cities | Earth Wise

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More than half of the world’s population lives in cities and by 2100, this percentage is predicted to be much higher.  This means that more homes will be built with steel and concrete, which both have very large carbon footprints.  According to a study by the Potsdam Institute in Germany, housing a growing population in homes made of wood instead could avoid more than 100 billion tons of carbon dioxide emissions over the remainder of the century.  This is about 10% of the remaining global carbon budget for staying below the 2-degree Celsius climate target.

The study presents the alternative of housing new urban populations in mid-rise buildings – no more than 4-12 stories high – that are substantially made of wood.  Wood is a renewable resource that carries the lowest carbon footprint of any comparable building material.  Trees take up CO2 from the atmosphere to grow.  Producing engineered wood releases far less CO2 than production of concrete and steel and the finished product continues to store carbon.

The study shows that sufficient wood for new mid-rise urban buildings can be produced without a major impact on food production.  The wood would come from timber plantations as well as natural forests.  The study also looked at biodiversity impacts and ways that ecosystems could be protected while still providing the necessary timber.

Overall, the Potsdam study demonstrates that urban homes made out of wood could play a vital role in climate change mitigation based on their long-term carbon storage potential coupled with the reduced utilization of the carbon-intensive concrete and steel industries.

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Living in timber cities could avoid emissions – without using farmland for wood production

Photo, posted May 24, 2005, courtesy of Stig Anderson 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.

Floating Homes In The Netherlands | Earth Wise

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The Netherlands is a country that is largely built on reclaimed land and a third of it remains below sea level.  The Dutch have long experience with dealing with rising waters.  The city of Amsterdam has almost 3,000 houseboats in its canals.

As sea levels continue to rise across the globe, it is no surprise that the Dutch have taken the lead in creating communities composed of floating houses and buildings.

A floating house is a structure fixed to the shore, often resting on steel poles, and usually connected to the local sewer system and power grid.  They are much like ordinary houses except that instead of a basement, they have a concrete hull that acts as a counterweight, allowing them to remain stable in the water.

The ones in the Netherlands are often prefabricated, square-shaped, three-story townhouses.  Rotterdam, which is 90% below sea level, is home to the world’s largest floating office building as well as a floating farm.

Floating buildings have their challenges, not the least of which are the effects of severe wind and rainstorms, or even the passing of large ships which can make the buildings rock.  Infrastructure like electricity and sewer service is not that simple to implement for the buildings.  But the benefits of floating buildings may outweigh the costs.

For cities facing worsening floods and a shortage of buildable land, floating homes are a potential solution for expanding urban housing in the age of climate change.  Dutch engineers are spearheading floating building projects in Britain, France, and Norway, as well as in threatened island locations like French Polynesia and the Maldives.

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Embracing a Wetter Future, the Dutch Turn to Floating Homes

Photo, posted May 23, 2007, courtesy of Jeff Hutchison via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Reducing Emissions From Cement Manufacturing | Earth Wise

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Cement is the basic ingredient of concrete, which is the most widely used construction material in the world.  About 8% of global carbon dioxide emissions are associated with cement production.

More than half of these emissions come from making clinker, which is a major component of cement produced by heating ground limestone and clay to a temperature of over 2500 degrees Fahrenheit.  Some of the emissions come from burning fossil fuels to heat the materials, but much of them come from the chemical reaction that creates the clinker.

The Portland Cement Association, which represents 92% of US cement manufacturing capacity, has recently released its “Roadmap to Carbon Neutrality”, which lays out a plan to reach carbon net zero across the cement and concrete value chain by 2050.

The plan includes the greater use of alternative fuels to reduce emissions from energy use.  It also involves the adoption of newer versions of cement such as Portland limestone cement, which reduces CO2 levels.  The industry has already reduced emissions by some shifting to Portland limestone cement, but it still only represents a small fraction of cement production.

The most significant strategy would be the adoption of carbon capture, utilization, and storage (or CCUS) technologies.  The idea is to capture the CO2 generated in the production of clinker and inject it into the fresh concrete.  It would actually be permanently sequestered in the concrete and would not be released even if a structure is demolished in the future.

It will take a combination of technologies and initiatives for the cement industry to reduce its emissions.  Fortunately, the industry appears to be committed to that goal.

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US cement manufacturers release their road map to carbon neutrality by 2050

Photo, posted March 26, 2014, courtesy of Michael Coghlan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Decarbonizing The Most Polluting Heavy Industries | Earth Wise

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The production of steel, cement, and ammonia accounts for about 20% of the carbon dioxide humans pour into the atmosphere.  Modern cities are largely constructed from concrete and steel and most of our food is grown using fertilizer made from ammonia. 

The most widely discussed solutions to decarbonizing these industries are green hydrogen and carbon capture and storage or CCS.

Steel manufacture is responsible for 11% of society’s emissions.  Most production starts by burning coal in a blast furnace. Using CCS could reduce emissions from burning the coal.  But the blast furnace could be eliminated entirely by the use of electrolysis to produce the pure iron needed to make steel.  This would be extremely energy-intensive but using a low-carbon source like green hydrogen could greatly reduce the emissions from making steel.

Ammonia is made by producing hydrogen from natural gas and then combining it with atmospheric nitrogen.  Both the hydrogen production and ammonia synthesis are energy intensive.  Using green hydrogen would eliminate emissions from the hydrogen production itself and new research on catalysts aims at lower-temperature, less-energy intensive ammonia synthesis.

Decarbonizing cement manufacturing is perhaps the toughest challenge.  Cement is made in a high-temperature kiln, typically heated by burning fossil fuels.  The process converts calcium carbonate and clay into a hard solid called clinker.  The main byproduct of that is even more carbon dioxide.  Burning green hydrogen and capturing carbon emission are about the best hope for reducing cement manufacturing emissions.

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Can the World’s Most Polluting Heavy Industries Decarbonize?

Photo, posted June 30, 2009, courtesy of Portland Bolt via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Green Hydrogen | Earth Wise

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Saudi Arabia is a country built around oil, but it is now placing a big bet on green hydrogen as the next big thing in its energy future.  The country is constructing a $500 billion futuristic city called Neom in the desert along the Red Sea.  The brand-new city will be home to a million people, and it will be powered by green hydrogen.

The U.S. company Air Products & Chemicals has been building a green hydrogen plant there for the last four years.  The giant plant will be powered by 4 gigawatts of wind and solar projects.

Green hydrogen is hydrogen produced without carbon emissions.  Most hydrogen produced commercially is made from natural gas, which results in CO2 emissions.  Green hydrogen is made by using electricity to split water into its component elements using renewable energy to power the process.

Saudi Arabia is an ideal place for a giant green hydrogen plant.  The Middle East has the world’s cheapest wind and solar power.  The sun reliably shines there almost every day and the wind blows almost every night.

While some proponents argue that hydrogen should fuel the entire energy system, other experts see it as a more targeted solution.  The view is that wind and solar power can provide the electricity we need to power homes and electric cars.  However, green hydrogen could be ideal to power energy-intensive industries like concrete and steel manufacturing, as well as parts of the transportation sector that are more difficult to electrify.

While green hydrogen is barely on the radar in the US, around the world a green hydrogen rush is underway, developing it as an energy source that could help end the reign of fossil fuels.

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Green Hydrogen: Could It Be Key to a Carbon-Free Economy?

Photo, posted November 6, 2020, courtesy of RSM Chrystie via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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