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Industrial heat and solar power

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Many industrial processes require extremely high temperatures, typically more than 1,800 degrees Fahrenheit.  This heat is generally produced by burning fossil fuels – either coal or natural gas – which emits large amounts of greenhouse gases. This level of heat cannot be economically produced using renewable electricity.  As a consequence, decarbonizing these industrial processes is very difficult.

Researchers at ETH Zurich in Switzerland have recently demonstrated a new method of obtaining high-temperature heat based on solar radiation.  They have engineered a device called a thermal trap.  It consists of a quartz rod coupled to a ceramic absorber that can efficiently absorb sunlight and convert it to heat.

In laboratory-scale experiments, they exposed a foot-long quartz rod to artificial light 135 times more intensive than sunlight and were able to produce temperatures as high as 1,900 degrees.  The artificial light source was needed to mimic the effects of concentrated solar energy plants that typically make use of large numbers of mirrors to direct intense solar energy onto a small area.

There are already concentrated solar power plants that operate at temperatures as high as 1,100 degrees and use the heat to operate turbines to generate electricity.  These plants lose efficiency at higher temperatures because of radiative heat losses.  The Zurich thermal trap minimizes these losses and permits higher temperature operation.

The hope is that at a large scale, the new approach may make it possible to use solar energy to decarbonize energy-intensive industrial processes.

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Using solar energy to generate heat at high temperatures

Photo courtesy of ETH Zurich / Emiliano Casati.

Earth Wise is a production of WAMC Northeast Public Radio

Natural hydrogen

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Hydrogen is considered to be a potential substitute for conventional fossil fuels in applications where electricity cannot easily be used such as in blast furnaces, cement works, industrial heating, long-distance aviation, and shipping.  But most hydrogen is manufactured by separating it from methane, which is energy-intensive and produces carbon dioxide.  So-called green hydrogen is made by splitting water using electricity.  It is a carbon-free process if the electricity is from renewable sources, but it is pretty expensive.

A small community in Mali gets its electricity by burning natural hydrogen, which bubbles up from underground into a village well.  It has long been known that processes in the Earth’s crust can make hydrogen gas from water under certain circumstances.  But conventional wisdom has been that this occurrence is rare and that the hydrogen produced is either inaccessible or seeps away.

An increasing number of geoscientists now are convinced that there is actually an enormous quantity of hydrogen beneath the planet’s surface and that we just haven’t been looking for it in the right places, or at all, for that matter.  Some say that there could be trillions of tons of hydrogen, and more is being generated all the time.

Prospectors have recently been drilling for hydrogen in France, Australia, Morocco, Brazil, and in the United States, in Nebraska, Arizona, and Kansas.  Will extracting natural hydrogen be practical at the scale required and will it be economical?  The jury is still out on all of this, but if it turns out as proponents claim, natural hydrogen could be a very big deal.

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Natural Hydrogen: A Potential Clean Energy Source Beneath Our Feet

Photo, posted November 4, 2012, courtesy of Heather Paul via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Self-Deicing Roads | Earth Wise

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Driving on snowy or icy roads can be pretty dangerous.  That is why roads are salted or coated with sand to provide traction in icy weather.  But excessive use of these substances is bad for the environment and sometimes a storm will blow in before the roads can be coated.

In a paper published in the American Chemical Society Journal ACS Omega, researchers in China describe a method of adding microcapsules filled with a chloride-free salt mixture to the asphalt with which roads are paved.  The idea is to provide the road itself with long-term snow melting capabilities.

The researchers prepared a sodium-acetate salt and combined it with a surfactant, silicon dioxide, sodium bicarbonate, and blast furnace slag, which is a waste product from power plants.  The substances were reduced to a fine powder and then coated with a polymer solution to form tiny microcapsules.  The microcapsules were then used to replace some of the standard mineral filler in asphalt.

Lab experiments showed that the special additive lowered the freezing point of water on the asphalt to -6 degrees Fahrenheit.   The researchers estimated that a 2-inch-thick layer of the anti-icing asphalt would be effective at melting snow for seven or eight years.  A real-world pilot test of the coating on a highway offramp showed that it melted snow that fell on the road whereas an uncoated road required snow removal operations.

According to the researchers, given the cost of materials used for the coating and its potential useful lifetime, it could be a practical and economic enhancement for wintertime snow and ice removal.  Maybe we’ll someday have roads that can fairly often deice themselves. 

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Keeping drivers safe with a road that can melt snow, ice on its own

Photo, posted April 8, 2007, courtesy of the Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Turning Pollution Into Cash | Earth Wise     

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Power plants and other industrial facilities are a major source of carbon emissions.  There are a variety of techniques under development to prevent those emissions by capturing them rather than releasing them into the atmosphere.  All of them add costs to the functioning of the facility.  A good way to offset those costs is to convert the emissions into useful products, ideally making it profitable to capture emissions.

Engineers at the University of Cincinnati have developed an electrochemical system that converts carbon dioxide into ethylene, which is a chemical used in a wide range of manufacturing.  Ethylene has sometimes been called “the world’s most important chemical”.  It is used in many kinds of plastics, textiles, and the rubber found in tires and insulation. It is also used in heavy industry such as steel and cement plants as well as in the oil and gas industry.

The Cincinnati process is a two-stage cascade reaction that converts carbon dioxide to carbon monoxide and then into ethylene.  It is based on the underlying principle of the plug-flow reactor that is used for variety of production applications.  The study, published in the journal Nature Catalysis, demonstrates that the process has high ethylene selectivity – meaning that it effectively isolates the desired compound – as well as high productivity – meaning that it makes a lot of it.  The system will take more time to become truly economical, but the researchers are continuing to make progress on that front with improved catalysts.

The researchers believe that this technique can reduce carbon emissions and make a profit doing it.  Power plants and other facilities emit a lot of carbon dioxide.  With this process, it may be possible to capture it and produce a valuable chemical.

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Conversion process turns pollution into cash

Photo, posted February 27, 2018, courtesy of Cyprien Hauser via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wastewater As A Freshwater Source | Earth Wise

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Water covers three-quarters of our planet, but freshwater – the water we drink, bathe in, and irrigate crops with – comprises only 3% of the world’s water and much of that is frozen in glaciers or otherwise unavailable.  Nearly 3 billion people suffer from water scarcity for at least some of the year.

Natural freshwater sources – lakes, rivers, and groundwater – are under stress from the effects of climate change and from the increasing demands of city populations.  The wastewater treatment plants in large cities represent a significant potential water source provided that sustainable and economical technologies to produce it can be developed.

Researchers at Lehigh University in Pennsylvania have patented an innovative ion exchange desalination process that is a legitimate candidate to transform wastewater into usable water.

Existing large-scale desalination systems make use of semipermeable reverse osmosis membranes that require an energy source to run the system.  The Lehigh process, which they call HIX-Desal, harnesses the unique chemistry of carbon dioxide to take the place of the energy used in reverse osmosis systems. 

Tests of the new system show that the salinity of treated wastewater can be reduced by more than 60% by the HIX-Desal process without requiring any reverse osmosis.  At an Allentown, Pennsylvania water treatment plant where the system was tested, the researchers estimated that using the system could save about a million kWh per day in electricity usage, enough energy to power 94 homes for a year.

With this system, waste carbon dioxide from landfills or turbine exhaust can be used to desalinate municipal wastewater.  It could be the basis of a circular economy.

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Desalination tech uses CO2 to tap into municipal wastewater as alternative freshwater source

Photo, posted November 28, 2020, courtesy of Richard Ricciardi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Better Ways To Make Bioplastics | Earth Wise

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The world produces over 300 million tons of plastics each year, mostly produced from petroleum.  The environmental consequences are substantial and there is a critical need to replace as much of that plastic production with biodegradable plastics as possible.  Thus, there is global research aimed at making bioplastics more economical and as environmentally friendly as possible.

Researchers at Texas A&M University have developed an improved approach for making bioplastics from corn stubble, grasses, and mesquite agricultural production.  Apart from the obvious environmental benefits of having biodegradable plastics, producing bioplastics from common agricultural waste would create new revenue streams for farmers as well as the people who transport harvested feedstock and byproduct crops to refinery operations.

The key to bioplastic production is the efficient extraction and use of lignin, the organic polymer that is the primary structural support material in most plants.  The new research takes five conventional pretreatment technologies for plant materials and modifies them to produce both biofuel and plastics together at a lower cost.  The new method is called “plug-in preconditioning processes of lignin” and it can be directly and economically added into current biorefineries.  The process is designed to integrate dissolving, conditioning, and fermenting lignin, extracting energy from it and making it easily adaptable to biorefinery designs.

The so-called bioeconomy currently supports some 286,000 jobs.  Innovation is the key to achieving more widespread use of biodegradable plastic.  With improved economics of so-called lignocellulosic biorefineries, there can be new avenues to use agricultural waste to produce biodegradable plastics.

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‘Plugging in’ to produce environmentally friendly bioplastics

Photo, posted November 5, 2015, courtesy of Kathryn Faith via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Getting Value From Plastic Waste | Earth Wise

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To date, the world has produced more than five billion tons of plastic and is making more all the time.  Based on the way things are currently done, most of that will end up in landfills or in the natural environment.  By 2050, the amount of plastic is expected to exceed 13 billion tons.   This is one of the world’s biggest environmental problems.

Recently, an international collaboration by universities and institutions in the UK, China, and Saudi Arabia has developed a method of converting plastic waste into hydrogen gas and high-value solid carbon.

The technique was achieved with a new type of catalysis that uses microwaves to activate catalyst particles that effectively strip hydrogen from plastic polymers.  The work was recently published in the journal Nature Catalysis and details how the researchers mixed mechanically pulverized plastic particles with a microwave-susceptor catalyst of iron oxide and aluminum oxide.  That mixture was then subjected to microwave treatment and yielded a large volume of hydrogen gas and a residue of carbonaceous material, most of which was identified as carbon nanotubes.

The process is more rapid than most methods for dealing with plastic waste and can extract over 97% of the hydrogen in plastic without producing any carbon dioxide emissions. 

The new method represents an attractive potential solution to the problem of plastic waste.  Instead of polluting the planet, plastics could become a valuable feedstock for producing clean hydrogen fuel as well as valuable carbon materials.  Proponents of the so-called hydrogen economy have continued to seek a green and economical way to produce hydrogen.  This new work might be just what they are looking for.

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Turning plastic waste into hydrogen and high-value carbons

Photo, posted April 21, 2007, courtesy of Redwin Law via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Hydrogen From Water And Sun

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There are research efforts around the world seeking ways to produce hydrogen starting from water and using clean energy.  Finding an economical and scalable way to do this is a key to the so-called hydrogen economy.

A recent study at Argonne National Laboratory makes use of a chemical reaction pathway central to plant biology to create a process that converts water into hydrogen using energy from the sun.

The process combines two membrane-bound protein complexes to perform the conversion of water molecules into hydrogen and oxygen.

The first protein complex, which the researchers call Photosystem I, is a membrane protein that uses energy from light to feed electrons to an inorganic catalyst that makes hydrogen.  But this represents only half of the overall process.

A second protein complex that they call Photosystem II uses energy from light to split water and take electrons from it.  The electrons are then fed to Photosystem I.

The two protein complexes are embedded in thylakoid membranes, which are like those found inside the oxygen-creating chloroplasts in plants.  This membrane is an essential part of pairing the two photosystems.  It supports both of the photosystems and provides a pathway for transferring electrons between the proteins.

The researchers also make use of a synthetic catalyst made from nickel or cobalt that replaces expensive platinum catalysts used in conventional water-splitting schemes.  Combining the light-triggered transport of electrons with the synthetic catalyst results in what the researchers call the “Z-scheme”, an adaptation of photosynthesis to produce hydrogen.

The next step is to incorporate the scheme into a living system which the researchers hope will lead to a practical system for hydrogen production.

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Discovery adapts natural membrane to make hydrogen fuel from water

Photo, posted December 25, 2017, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Oman’s Rocks

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There is growing interest in the idea of capturing and storing carbon dioxide.  Reducing the amount of it we are putting into the atmosphere is essential for limiting the effects of climate change, but even eliminating emissions entirely is not enough because the CO2 already there stays in the atmosphere for decades or more.

[Read more…] about Oman’s Rocks

New Energy Goals For New York

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Since 2015, New York has had in place an energy plan aimed at building a clean, resilient and cost-effective energy system for the state.  A key part of that plan is to reduce greenhouse gas emissions by 40% from 1990 levels by the year 2030.  Another major goal is to have 50% of the state’s electricity produced from renewable sources by the same year.

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Fuel From Greenhouse Gases

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Carbon dioxide and methane are the two greenhouse gases that are having the greatest impact on the global climate.  There are basically three ways to prevent them from getting into the atmosphere:  don’t emit them, trap them and store them away, or turn them into something useful.

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