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Seaweed and concrete

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Modern civilization is pretty much made of concrete.  People use more concrete than any other substance apart from water.  But concrete is made from cement, and cement is the source of 10% of all carbon dioxide emissions worldwide.

Researchers at the University of Washington and Microsoft have developed a new kind of concrete made by mixing dried, powdered seaweed with cement.  By fortifying cement with seaweed, the global warming potential of the concrete is reduced by 21% without weakening it. 

This novel recipe for concrete was developed using machine learning models, arriving upon it in a fraction of the time it would have taken by traditional experimentation.

Producing cement leads to carbon emissions from the fossil fuels used to heat raw materials and from a chemical reaction called calcination that occurs during the production process.  Seaweed is a carbon sink that pulls carbon dioxide out of the air and stores it while it grows.  By replacing some of cement in concrete, the resultant product has a much smaller carbon footprint.

Machine learning was used to predict the ideal mixture of cement and seaweed to yield concrete with a reduced carbon footprint that still passed mechanical strength tests.  Finding the right mixture would have taken 5 years ordinarily, but the machine learning process took only 28 days.

The researchers plan to generalize their work to different kinds of algae and even to food waste or other natural materials in order to create local, sustainable cement alternatives around the world. 

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Seaweed-infused cement could cut concrete’s carbon footprint

Photo, posted June 29, 2009, courtesy of Peter Castleton via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A hidden cost of climate change

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Climate change is dramatically impacting food production by altering rainfall patterns, increasing temperatures, and triggering more frequent extreme weather events.  These changes make crops more vulnerable to droughts, floods, heatwaves, pests, and diseases, leading to lower yields and greater uncertainty for farmers worldwide.

But climate change isn’t just reshaping our planet.  It’s also changing what’s on our plates.  According to a new study by researchers from Liverpool John Moores University in the UK, rising carbon dioxide levels and warmer temperatures may be making food less nutritious.

The research team focused on popular leafy vegetables, including kale, rocket, and spinach.  The researchers simulated future UK climate conditions in growth chambers to study how the crops responded to hotter, CO2-rich environments.

The research team found that elevated CO2 levels help crops grow faster and bigger, but not healthier.  Over time, the crops showed a reduction in key minerals like calcium and certain antioxidant compounds.  These changes were exacerbated by increases in temperature.  In fact, the combination had complex effects.  The crops did not grow as big or fast, and the decline in nutritional quality intensified.

This nutritional imbalance poses serious human health implications.  Rising CO2 levels can increase sugar in crops while reducing essential nutrients, leading to calorie-rich but nutrient-poor diets. This shift may raise the risk of obesity, diabetes, and nutrient deficiencies, especially in vulnerable populations.

The challenge ahead isn’t just to grow enough food to feed a growing population, but to preserve the quality of that food in a changing climate.

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Bigger crops, fewer nutrients: The hidden cost of climate change

Photo, posted May 25, 2010, courtesy of Jason Bachman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Soda can hydrogen

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Hydrogen is an ideal climate-friendly fuel because it doesn’t release carbon dioxide when it is used.  But most hydrogen is produced in ways that result in significant carbon emissions. Thus, the search for green hydrogen goes on. 

Last year, engineers at MIT developed a new process for making hydrogen that significantly reduces the carbon footprint of its production.  The recipe uses seawater and recycled soda cans. 

Pure aluminum reacts with water, breaking up the water molecules to produce aluminum oxide and pure hydrogen.  But when aluminum is exposed to oxygen, it forms a shield-like layer that prevents the reaction.

The MIT researchers found that the shield can be removed by treating aluminum with a small amount of gallium-indium alloy.  Mixing the pure aluminum with seawater not only produces hydrogen, but the salt in the seawater precipitates out the gallium-indium, making it available for reuse.

The research team carried out a “cradle-to-grave” life cycle assessment of the process, taking into account every step in using the hydrogen-production process at an industrial scale.  They found that using recycled aluminum – chopped-up soda cans – is environmentally and economically superior to using “primary” aluminum, mined from the earth. The cans would be shredded into pellet and treated with the gallium-indium alloy.  The pellets would be processed near a source of seawater where they would be combined to generate hydrogen on demand.

According to their analysis, the hydrogen produced would be at least competitive economically and environmentally with other potential methods of producing green hydrogen.

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Study shows making hydrogen with soda cans and seawater is scalable and sustainable

Photo, posted July 29, 2020, courtesy of Bruce Dupree via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

AI and greener cement

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Cement pretty much holds the modern world together.  The amount of cement required to create our infrastructure is almost incomprehensible.   By weight, humanity consumes more cement than food, about 3 pounds per person per day.  The cement industry produces around eight percent of global CO2 emissions, which is more than the aviation industry.  So, if the amount of emissions produced making concrete could be reduced by even a few percent, it would make a significant impact.

Cement plants utilize rotary kilns heated to 2,500 degrees Fahrenheit to burn ground limestone down to a substance called clinker.  That energy-intensive combustion process emits large amounts of carbon dioxide.  However, the combustion process accounts for much less than half of the emissions associated with making concrete.  The majority comes from the raw materials needed to produce clinker.

One strategy to reduce concrete emissions is to modify the cement recipe itself, replacing some of the clinker with alternative materials.  Some producers already make use of materials like slag from iron production and fly ash from coal-fired power plants.   

A team of researchers at the Paul Scherrer Institute in Switzerland is making use of machine learning to simulate and optimize cement formulations that would emit significantly less CO2 while maintaining the same high level of mechanical performance.  This AI-based approach eliminates time-consuming experiments and conventional complex simulations.

The Scherrer Institute seeks to discover new materials and the effort has already yielded some promising candidates.  The next steps will be testing some of these recipes in the laboratory. 

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AI paves the way towards green cement

Photo, posted July 3, 2007, courtesy of Tim Shortt via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Planting trees to cool the planet

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Planting lots of trees is one of many strategies being pursued to combat climate change. Forests absorb carbon dioxide, provide shade, and help regulate temperatures. They also support biodiversity and improve air and water quality.

According to a new study by researchers from the University of California – Riverside, restoring forests to their pre-industrial extent could reduce global average temperatures by 0.34 degrees Celsius. That’s equivalent to about 25% of the warming the Earth has already experienced.

The study models restoring 4.6 million square miles of forest.  While previous studies have focused on the role trees play in removing carbon, this research adds that trees also alter atmospheric chemistry in ways that boost their cooling impact.

Trees release natural chemicals called BVOCs – biogenic volatile organic compounds – which interact in the atmosphere to form particles that reflect sunlight and promote cloud formation. These effects enhance the cooling impact of forests, especially in climate models that take these chemical reactions into account.

But not all reforestation is created equal. The benefits of reforestation vary by region, with tropical forests offering stronger cooling and fewer drawbacks.  Importantly, the researchers emphasize that meaningful climate benefits don’t require restoring every lost forest. Small, localized efforts can still shift regional climates.

While forest restoration can meaningfully aid climate efforts, the researchers stress that it must complement – not replace – fossil fuel reductions.

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Does planting trees really help cool the planet?

Photo, posted May 20, 2005, courtesy of Ben Britten via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tracking emissions by satellite

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Carbon dioxide and nitrogen oxides are two of the most problematic human-generated air pollutants that negatively impact air quality, the climate, and human health.  Satellites are an important tool for monitoring emissions of these pollutants, but they have limitations.  For the most part, satellites have limited spatial resolution, meaning that they can’t reliably narrow down the source of emissions sufficiently to pin down a specific location such as a power plant. 

Until now, there have been no instruments that can detect both carbon dioxide and nitrogen oxide simultaneously with high spatial resolution.  Often just nitrogen oxide measurements are made, and carbon dioxide levels estimated based on the fact that both are emitted together with typical ratios.

A German research team from the Max Planck Institute and the Heidelberg Institute have developed a technology for the EnMAP environmental satellite to detect both gases with an unprecedented spatial resolution of 30 meters.  Data from the satellite makes it possible to track multiple sources of emission plumes over several tens of kilometers.

The EnMAP system was originally designed for remote sensing of land surfaces.  The new research demonstrates that reliable measurements of trace gases are possible even with an instrument not specifically designed for atmospheric observations.  When using it, it’s possible to determine the distribution of carbon dioxide and nitrogen oxide in emission plumes from individual power plants.  The ability to measure both gases individually means that conclusions can be drawn about the technology, efficiency, and operating mode of the systems being measured.

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German satellite measures CO2 and NO2 simultaneously from power plant emissions for the first time

Photo, posted September 19, 2020, courtesy of Sandor Somkuti via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Finding peatlands

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Peatlands are a special kind of wetland that have enormous potential for helping to mitigate climate change.  They are great at capturing carbon because their constantly soggy soils deprive decomposer organisms of the oxygen they need to break down dead plants.  Living plants absorb carbon dioxide from the atmosphere and incorporate the carbon into their tissues.  When plants die, decomposers like bacteria digest the plant matter and release the carbon dioxide back into the atmosphere.

Researchers from the University of California Santa Cruz found that the average per-area carbon densities in peatlands in Colombia are four to ten times higher than those in the Amazon rainforest.  This agrees with other studies around the world.  On a global scale, peatlands cover only 3% of land areas but store more carbon than all the world’s trees.  Peatlands are unsung heroes helping to reduce the impact of fossil fuel emissions.

Peatlands can only store carbon if they remain constantly wet.  When they are drained for agriculture or other development, decomposer organisms get back to work digesting organic matter and releasing carbon dioxide back into the atmosphere.

A major challenge in protecting peatland is finding them.  They are often hard to distinguish from other types of wetlands. 

The Santa Cruz researchers have been identifying and locating peatlands in Colombia, where decades of civil war had made many parts of the country inaccessible for research.  Finding and protecting peatlands there and in many other places around the world is an important task in the battle against climate change.

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Colombia’s peatlands could be a crucial tool to fight climate change. But first we have to find them.

Photo, posted January 2, 2018, courtesy of Roni Ziade / U.S. Forest Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The warmer, greener Arctic and greenhouse gas

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About 15% of the Northern Hemisphere is covered by permafrost.  Permafrost is soil and sediment that has remained frozen for long periods of time, in some cases as much as 700,000 years.  It contains large amounts of dead biomass that has accumulated over millennia and hasn’t fully decomposed.  Therefore, permafrost is an immense carbon sink.

The Arctic is warming four times faster than the rest of the planet and, as a result, thawing permafrost is becoming a carbon source.  As warming continues, ice is melting, and vegetation is spreading.    A new study, published in Nature Climate Change, looked at the state of the Arctic and boreal north from the period 1990 until 2020.  The study found that although half of the Arctic region has been growing greener, only 12% of those green areas are actually taking up more carbon.  For one thing, the growth of forests means that there is more fuel for wildfires which are increasingly common.

A study of lakes in West Greenland found that thousands of crystal blue lakes have turned brown during record heat spells.  Runoff from melting permafrost made the lakes opaque killing off plankton that absorb carbon dioxide.  Meanwhile, plankton that release carbon dioxide multiplied.  So, these lakes went from being carbon sinks to being carbon sources.

As the northern latitudes warm, ice and permafrost are melting, vegetation is spreading, and the region is becoming a source of heat-trapping gas after having been a place where carbon has been locked away for thousands of years.  According to the Nature Climate Change study, roughly 40% of the Arctic is now a source of carbon dioxide.

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Warmer, Greener Arctic Becoming a Source of Heat-Trapping Gas

Photo, posted October 14, 2024, courtesy of Christoph Strässler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

New highs for carbon dioxide

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Last year was the hottest year on record and the ten hottest years on record have in fact been the last ten years.  Ocean heat reached a record high last year and, along with it, global sea levels.  Those are rising twice as fast as they did in the 1990s.

The World Meteorological Organization reports that the global atmospheric concentration of carbon dioxide reached a new observed high in 2023, which is the latest year for which global annual figures are available.  The level was 420 ppm, which is the highest level it has been in 800,000 years. 

The increase in carbon dioxide levels was the fourth largest one-year change since modern measurement began in the 1950s.  The rate of growth is typically higher in El Niño years because of increases from fire emissions and reduced terrestrial carbon sinks.

Concentrations of methane and nitrous oxide – which are two other key greenhouse gases – also reached record high observed levels in 2023.  Levels of both of these gases have also continued to increase in 2024.

The annually averaged global mean near-surface temperature in 2024 was 1.55 degrees Celsius above the 1850-1900 average.  Apart from being the warmest year in the 175 years records have been kept, it is also above the 1.5-degree limit set as the goal of the Paris Climate Agreement.  While a single year above 1.5 degrees of warming does not mean that the efforts to limit global warming have failed, it is a strong warning that the risks to human lives, economies, and the planet are increasing.

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Carbon Dioxide Levels Highest in 800,000 Years

Photo, posted January 30, 2018, courtesy of Johannes Grim via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Green grout for stabilizing buildings

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We are all familiar with the grout that is used for tiles in our homes. We are less familiar with grout that is used to stabilize the soil beneath buildings.  Grouting is a process of ground improvement by injecting materials that can fill voids and cracks, strengthen and increase the bearing capacity of soil, and reduce permeability.

Traditional grouting methods have environmental downsides.  Most often, silica-based chemical grouts are used, and they are produced through energy-intensive processes that contribute substantially to carbon dioxide emissions.  As is the case for all materials and practices of the construction industry, developing sustainable, low-emission alternatives to conventional grouting materials has become an important priority.

Researchers from the Shibaura Institute of Technology in Japan have developed an innovative new grout material called Colloidal Silica Recovered from Geothermal Fluids.  This grout material enhances soil stabilization and simultaneously reduces the environmental impact of geothermal energy harvesting.

Geothermal energy production generates large amounts of silica-rich waste fluids which creates challenges for its maintenance and disposal.  The new grout repurposes this waste material thereby transforming an industrial byproduct into a valuable construction material.

The new grout material is particularly valuable in earthquake-prone regions, where soil stabilization is essential in preventing structural damage during seismic events.  In addition, the grout’s superior water-sealing properties makes it ideal for underground construction projects like tunnels, subways, and basements.  The new grout in an important step for the construction industry’s efforts to achieve carbon neutrality.

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From Waste to Wonder: Revolutionary Green Grout for Sustainable Construction Practices

Photo, posted July 8, 2011, courtesy of MTA Construction & Development Mega Projects via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Trapping carbon with rocks

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Many experts say that combating global warming will require both drastically reducing the use of fossil fuels and permanently removing billions of tons of CO2 already in the atmosphere.  Developing practical, large-scale technologies for carbon removal is a significant challenge.

There is a nearly inexhaustible supply of minerals that are capable of removing carbon dioxide from the atmosphere, but they don’t do it quickly enough to make a significant dent in the ever-growing supply in the atmosphere.  In nature, silicate minerals react with water and atmospheric CO2 to form minerals in the process called weathering.  But this chemical reaction can take hundreds or even thousands of years.

Researchers at Stanford University have developed a new process for converting slow-weathering silicates into much more reactive minerals that capture and store carbon quickly.  The new approach resembles a centuries-old technique for making cement.  They combine calcium oxide and another common mineral containing magnesium and silicate ions in a furnace.   The result are new materials that, when exposed to water, quickly trap carbon from the atmosphere.

In their experiments, the carbonation process took weeks to months to occur, thousands of times faster than natural weathering.

The idea would be to spread these materials over large land areas to remove CO2 from the air.  Meaningful use for trapping carbon would require annual production of millions of tons.  But the same kiln designs used to make cement could produce the needed materials using abundant minerals found in many places.  In fact, the required minerals are often common leftover materials – or tailings – from mining.

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Scientists discover low-cost way to trap carbon using common rocks

Photo courtesy of Renhour48 via Wikimedia.

Earth Wise is a production of WAMC Northeast Public Radio

Sharks and rays in a warming world

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Sharks and rays belong to a group of cartilaginous fish called elasmobranchs, which have been swimming in the world’s oceans for 450 million years. The resilient species have survived five mass extinction events, and are older than dinosaurs, trees, and Mount Everest. 

But despite their resilience, many species of sharks and rays today are threatened by human activities, including overfishing, habitat loss, and climate change.  In fact, according to a new study led by researchers from the University of Vienna in Austria, more than one third of the shark and ray species known today are severely under threat. 

The study, which was recently published in the journal Biology, found that higher carbon dioxide levels were having a negative effect on sharks and rays, ranging from impacts on the animals’ senses to changes in the skeleton during embryonic development.  An examination of fossil records found that higher CO2 levels had contributed to the extinction of individual shark and ray species in the past. 

But the study also found that global warming could be creating opportunities for sharks and rays.  Rising sea levels and higher temperatures have historically expanded shallow coastal habitats and warm waters, supporting species biodiversity.

But according to the research team, the rapid environmental changes, combined with the impacts from human activities, outpace the ability of sharks and rays to adapt, making it unlikely that they will benefit from global warming.

Protecting sharks and rays is crucial not only for their survival but also for maintaining entire ocean ecosystems. Without top predators, these ecosystems could collapse, impacting both marine life and the people and industries that depend on it.

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Sharks and rays benefit from global warming – but not from CO2 in the Oceans

Myths About Sharks and Rays

Photo, posted November 27, 2007, courtesy of Laszlo Ilyes via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Making hydrogen using bioengineering

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Hydrogen has great potential for helping society to reach net-zero emissions.  The problem is that the most economical and established production methods for hydrogen depend heavily on fossil fuels and result in roughly a dozen kilograms of carbon dioxide emissions for every kilogram of hydrogen produced.

The carbon-free way to produce hydrogen is by splitting water into its component elements.  This process generally requires the use of catalysts and lots of energy.

Researchers at the University of Oxford are developing a synthetic biology approach to the production of so-called green hydrogen.  The idea is to replace expensive, exotic metal-based catalysts with a highly-efficient, stable, and cost-effective catalyst based on genetically-engineered bacteria.

There are specific microorganisms that can naturally induce the chemical reaction that reduces protons to hydrogen by the use of hydrogenase enzymes.  While these reactions do occur naturally, they are limited to low hydrogen yields.

The Oxford researchers genetically engineered the bacterium Shewanella oneidensis by inserting a light activated electron pump called Gloeobacter rhodopsin as well as adding nanoparticles of graphene oxide and ferric sulfate.  All of this tinkering with the bacterium resulted in a ten-fold increase in hydrogen yield.

The researchers believe that their system, based entirely on biological methods rather than traditional chemical approaches, could be scaled up to produce ‘artificial leaves’ that, when exposed to sunlight, would immediately begin producing hydrogen.  The Oxford work was published last summer in the Proceedings of the National Academy of Science.

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A green fuels breakthrough: bio-engineering bacteria to become ‘hydrogen nanoreactors’

Photo, posted July 27, 2016, courtesy of Blondinrikard Froberg 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

Engineering plants to consume more carbon dioxide

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The most abundant protein on the planet is an enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase, better known as RuBisCO.  Its critical role in photosynthesis makes life as we know it on earth possible.  What it does is convert carbon dioxide from the atmosphere into the organic matter contained in plants.

Getting plants to take up more carbon dioxide from the atmosphere is a key strategy for mitigating climate change.  Planting lots of trees is one way to do it.  Another is to get individual plants to capture more carbon dioxide.

Scientists at the University of Illinois have focused on getting plants to produce more RuBisCO which allows them to grow faster, consuming more carbon dioxide in the process.

Some plants are better than others at taking advantage of the earth’s rising carbon dioxide levels.  Among these are food crops like corn, sugarcane, and sorghum.  Such plants’ growth is not primarily limited by how much carbon dioxide is in the atmosphere but rather by how much RuBisCO is in their leaves.  The Illinois scientists tweaked genes in corn and sorghum to produce plants containing more RuBisCO.  Laboratory experiments on corn demonstrated faster corn growth.  Recent outdoor field experiments on sorghum demonstrated a 16% boost in its growth rate. 

Improving photosynthesis in this way is not only a potential strategy for increasing plants’ ability to combat climate change.  It is also a way to cope with the world’s increasing demand for food by producing crops that can grow larger and more quickly.

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Scientists Engineer Crops to Consume More Carbon Dioxide

Photo, posted April 12, 2016, courtesy of K-State Research and Extension via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wrong trees in the wrong places

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Temperatures in cities are rising around the world and urban heat stress is already a major problem.  Extensive surfaces of man-made materials absorb the sun’s energy, and lead to temperatures well above those in the surrounding countryside.  This is known as the urban heat island effect, and it can lead to greater energy use, higher air pollution levels, and a greater risk of heat-related illnesses, as well as death. 

Some cities have already started implementing mitigation strategies, with tree planting prominent among them.  Planting trees can cool the climate by absorbing carbon dioxide, providing shade, and releasing water vapor, which lowers air and surface temperatures. 

However, while trees can cool cities significantly during the day, new research from the University of Cambridge in the U.K. shows that tree canopies can also trap heat and raise temperatures at night. 

According to the study, which was recently published in the journal Communications Earth & Environment, planting the wrong species or the wrong combination of trees in suboptimal locations or arrangements can limit their benefits.

The researchers found that in temperate climates, trees can cool cities by up to 6°C during the day but can increase nighttime temperatures by 1.5°C.  Cities with open layouts in temperate and tropical climates benefit from a mix of evergreen and deciduous trees, enhancing cooling by 0.5°C more than in cities with only deciduous or evergreen trees. 

The researchers hope their findings will help urban planners choose the best combinations of trees and planting locations to combat urban heat stress.

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Wrong trees in the wrong place can make cities hotter at night, study reveals

Photo, posted October 29, 2017, courtesy of Lars Plougmann 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

Hydrogen-powered aviation

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The transportation sector is responsible for about a quarter of human-generated greenhouse gas emissions.  Most of the energy used by transport systems comes from fossil fuels.  The transition to electric vehicles – cars, trucks, and buses – is making a real difference.  However, the emissions from the aviation industry have continued to grow faster than those of other forms of transportation.  There have been increased efforts to develop hydrogen-powered aircraft, but the challenges are substantial.

Hydrogen can be used for aviation both as a directly combusted fuel, or to power electric fuel cells.  Its advantages are that its use produces no carbon dioxide, and, in fact, hydrogen produces more energy per pound than jet fuel.

A study by researchers at MIT looked at the prospects for hydrogen use in aircraft and what needs to be done to make it practical.  The biggest issue is that the extra bulk of a hydrogen fuel tank and fuel cells in a plane would have to be offset by weight reductions elsewhere, such as reducing payload (cargo or passengers).  This would mean there would need to be more flights, thereby reducing the gains made.  The researchers argued that improvements in fuel cell power and more weight efficient fuel systems could eliminate the need for additional flights.

The bigger challenge is the infrastructure for generating and distributing hydrogen.  There needs to be green hydrogen – hydrogen produced without carbon emissions – and the infrastructure for getting it to planes where it is needed has to also not produce substantial emissions.

The study suggests that the rollout of hydrogen-based aviation should start at locations that have favorable conditions for hydrogen production.

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Fueling greener aviation with hydrogen

Photo, posted December 20, 2016, courtesy of Dylan Agbagni via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Capturing hot carbon dioxide

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Decarbonizing industries like steel and cement is a difficult challenge.  Both involve emitting large amounts of carbon dioxide both from burning fossil fuels and from intrinsic chemical reactions taking place.  A potential solution is to capture the carbon dioxide emissions and either use them or store them away.  But this sort of carbon capture is not easy and can be quite expensive.

The most common method for capturing carbon dioxide emissions from industrial plants uses chemicals called liquid amines which absorb the gas.  But the chemical reaction by which this occurs only works well at temperatures between 100 and 140 degrees Fahrenheit.  Cement manufacturing and steelmaking plants produce exhaust that exceeds 400 degrees and other industrial processes produce exhaust as hot as 930 degrees.

Costly infrastructure is necessary to cool down these exhaust streams so that amine-based carbon capture technology can work. 

Chemists at the University of California, Berkeley, have developed a porous material – a type of metal-organic framework – that can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams.  The molecular metal hydride structures have demonstrated rapid, reversible, high-capacity capture of carbon dioxide that can be accomplished at high temperatures.

Removing carbon dioxide from industrial and power plant emissions is a key strategy for reducing greenhouse gases that are warming the Earth and altering the global climate.  The captured CO2 can be used to produce value-added chemicals or can be stored underground or chemically-reacted into stable substances.

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Breakthrough in capturing ‘hot’ CO2 from industrial exhaust

Photo, posted March 3, 2010, courtesy of Eli Duke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Artificial plants to clean indoor air

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The average American spends about 90% of their time indoors breathing the air in our workplaces, homes, or schools.  The quality of this air affects our overall health and well- being.  Indoor air quality is an issue because many sources can generate toxic materials, including building materials, carpets, and more.  But high levels of carbon dioxide are a health hazard themselves. Indoor CO2 levels can often be 5 to 10 times higher than the already heightened levels in the atmosphere. 

Many of us make use of air purification systems, which can be expensive, cumbersome, and require frequent cleaning and filter replacements.

Researchers at Binghamton University in New York are working to develop artificial plants that consume carbon dioxide, give off oxygen, and, as a bonus, generate a little electricity. These artificial plants make use of the artificial light in the indoor environment to drive photosynthesis.  They achieve a 90% reduction in carbon dioxide levels, which is far more than natural plants can achieve.

The Binghamton researchers had been working on bacteria-powered biobatteries for various applications, but they repurposed the work into a new idea for artificial plants.  The artificial plants have “leaves” containing a biological solar cell and photosynthetic bacteria.  Their first plant had five leaves and demonstrated promising carbon dioxide capture rates and oxygen generation.  It also produced a little electricity.  If its generating capacity can be improved, it might also be useful for charging cell phones or other practical applications.

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Binghamton researchers develop artificial plants that purify indoor air, generate electricity

Photo, posted October 13, 2012, courtesy of F. D. Richards via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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