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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

An electric reactor for industry

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The industrial sector accounts for nearly a third of greenhouse gas emissions in the US, which is more than the annual emissions from cars, trucks, and airplanes combined.  These emissions primarily come from burning fossil fuels to produce goods from raw materials as well as from the chemical reactions associated with production.  Many industrial processes require very high temperatures that are not easily achieved other than by burning fossil fuels.

Researchers at Stanford University have developed and demonstrated a new kind of thermochemical reactor that can generate the huge amounts of heat required for many industrial processes that runs on electricity rather than the burning of fossil fuels.  The researchers claim that the design is also smaller, cheaper, and more efficient than the fossil fuel technology it would replace.

Standard industrial thermochemical reactors burn fossil fuel to heat a fluid that is piped into the reactor, much like the way home radiators work, albeit at far higher temperatures.  The new reactor uses magnetic induction, similar to the way that induction cooktops work.  Heat is transferred by inducing a current into materials that heat up as the current flows.

A proof-of-concept demonstration powered a chemical reaction called the reverse water gas shift reaction and resulted in more than 85% efficiency.  The reaction in question converts carbon dioxide into a valuable gas that can be used to create sustainable fuels. 

The Stanford researchers are working to scale up their new reactor technology and expand its potential applications.  They are working on designs for reactors for capturing carbon dioxide and for manufacturing cement. 

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Electric reactor could cut industrial emissions

Photo, posted October 30, 2022, courtesy of Helmut via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Less coal for making steel

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Steel is primarily produced using one of two methods:  blast furnaces or electric arc furnaces.  The first blast furnaces were built in the 14th century.  Making steel in a blast furnace starts by melting the raw materials of iron ore, limestone, and coal at very high temperatures.  The resultant reactions ultimately lead to two products:  iron saturated with carbon and carbon dioxide.  A second furnace reacts the liquid iron with oxygen to remove the carbon and results in steel along with even more carbon dioxide.

Making steel using an electric arc furnace is considerably less emissions-intensive and more sustainable.  So-called circular steel making powered by electric arc furnaces uses electricity to melt scrap and other input materials and turn them into high-quality steel.  Of course, to really minimize the emissions associated with steelmaking, the arc furnaces need to get their power from renewable energy sources. 

The global steel industry is turning away from polluting coal-fired blast furnaces and towards electric arc furnaces, which now account for roughly half of all planned new steelmaking capacity. This represents real progress towards a green steel transition.

By the end of this decade, electric arc furnaces will account for more than a third of steelmaking.  However, there are still plenty of new coal-based steel furnaces being built.  So even as electric arc furnaces account for a greater share of steelmaking, these new coal furnaces will still drive emissions upward.   Environmental advocates argue that what the steel industry needs is to make clean development a true priority and back away from coal-based developments.

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Steelmakers Increasingly Forgoing Coal, Building Electric

Photo, posted July 16, 2018, courtesy of Daniel Steelman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

EV battery costs continue to drop

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Electric vehicles have historically been more expensive than their gas-powered counterparts primarily because of the cost of the batteries that power them.  Today’s EV battery packs range in size from about 40 kWh to as much as 200 kWh, where kWh measure the amount of energy stored in pack.

The batteries in EVs are lithium-ion batteries, the same technology used to power cell phones, tablets, and computers.  A decade ago, the batteries averaged $668 per kilowatt-hour and packs as large as those in some of today’s vehicles were simply unthinkable from a price standpoint. 

Over the years, government subsidies, increased competition, higher volume, improvements in battery technology, and reductions in the cost of raw materials such as lithium have combined to drive continuous and dramatic reductions in battery costs.  By March 2022, the average price for lithium-ion batteries was $146 per kWh.  This past August, battery costs broke the $100 per kilowatt-hour barrier.

Industry analysts have long maintained that once the $100 barrier has been reached, EVs could achieve price parity with their fossil-fuel counterparts.  Electric cars would no longer be more expensive to buy than equivalent gas cars.

Projections are that battery prices will continue to fall by something like 10% a year for the rest of this decade.  All else being equal, EVs should be cheaper to buy than gas cars.  Of course, they have already been cheaper to operate for a long time. 

None of this means that car prices will go down in general.  That will depend on trends in inflation and those are pretty hard to predict.

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EVs Set to Match Gas Guzzlers in Price as Battery Costs Plummet

Photo, posted May 9, 2018, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Better Way To Recycle Plastic | Earth Wise

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The current state of plastic recycling is not very effective.  Plastic recycling is only able to replace 15-20% of the fossil-fuel-derived raw material needed to produce society’s demand for plastic.

Researchers at Chalmers University in Sweden have now demonstrated how the carbon content in mixed waste could be used to replace all of the fossil raw materials in the production of new plastic.  In principle, their technology could completely eliminate the climate impact of plastic materials.

According to the researchers, there are enough carbon atoms in waste to meet the needs of all global plastic production.

The Chalmers process is based on thermochemical technology and involves heating waste to 1100-1500 degrees Fahrenheit.  The waste is thereby vaporized and when hydrogen is added, becomes a carbon-based substance that can replace the fossil-fuel building blocks of plastic.  The method does not require sorting the waste materials.  Different types of waste, such as old plastic products and even paper cups, with or without food residues, can be fed into the recycling reactors.  The researchers are now developing the techniques required to utilize their recycling technology in the same factories in which plastic products are currently being made from fossil oil or gas.

The principle of the process is inspired by the natural carbon cycle in which plants break down into carbon dioxide when they wither and die, and then photosynthesis uses carbon dioxide and solar energy to grow new plants.

Producing new plastics would no longer require petroleum or other fossil fuels as raw materials.  If the energy needed to drive the recycling reactors is taken from renewable sources, plastics could become the basis of a sustainable and circular economy.

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Pioneering recycling turns mixed waste into premium plastics with no climate impact

Photo, posted August 10, 2013, courtesy of Lisa Risager via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lithium-Sulfur Batteries | Earth Wise

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The growing use of electric vehicles as well as energy storage systems has created a major focus on the batteries for these applications.  Lithium-ion batteries dominate these applications and the demand for the materials needed to manufacture them continues to grow.

The raw materials for these batteries include not only lithium, but also can include nickel, manganese, and cobalt. 

Sulfur has been a desirable alternative for use in lithium-based batteries for quite a while because it is an abundant element and can be extracted in ways that are safe and environmentally friendly.  However, previous attempts to create lithium batteries that combine sulfur cathodes and the standard carbonate electrolytes used in lithium-ion batteries have not been successful because of irreversible chemical reactions between intermediate sulfur products and the electrolytes.

A group of chemical engineers at Drexel University has now found a way to introduce sulfur into lithium-ion batteries that solves the stability problem and also has major performance advantages.  The new batteries have three times the capacity of conventional lithium-ion batteries, and last more than 4,000 recharges, which is also a substantial improvement.

The new battery technology involves creating a stable form of sulfur called monoclinic gamma sulfur by depositing the sulfur on carbon nanofibers.   Previously, this sulfur phase was only observed at high temperatures and was only stable for 20 or 30 minutes.  This chemical phase of sulfur does not react with carbonate electrolytes and therefore produces a battery that is chemically stable over time.

 Incorporating this sulfur into battery cathodes results in a better battery that doesn’t need any cobalt, nickel, or manganese.  It could be the next big thing in electric vehicle batteries.

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Breakthrough in Cathode Chemistry Clears Path for Lithium-Sulfur Batteries’ Commercial Viability

Photo, posted April 5, 2022, courtesy of Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Emissions-Free Cement

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The production of cement – which is the world’s leading construction material – is a major source of greenhouse gas emissions, accounting for about 8% of global man-made emissions. 

Cement production produces carbon dioxide in two ways:  from a key chemical process and from burning fuel to produce the cement.  The process of making “clinker” – the key constituent of cement – emits the largest amount of CO2.  Raw materials, mainly limestone and clay – are fed into huge kilns and heated to over 2,500 degrees Fahrenheit, requiring lots of fossil fuel.  This calcination process splits the material into calcium oxide and CO2.  The so-called clinker is then mixed with gypsum and limestone to produce cement.

A team of researchers at MIT has come up with a new way of manufacturing cement that greatly reduces the carbon emissions.  The new process makes use of an electrolyzer, where a battery is hooked up to two electrodes in water producing oxygen at one electrode and hydrogen at the other.  The oxygen-evolving electrode produces acid and the hydrogen-evolving electrode produces a base.  In the new process, pulverized limestone is dissolved in the acid at one electrode and calcium hydroxide precipitates out as a solid at the other.

High-purity carbon dioxide is released at the acid electrode, but it can be easily captured for further use such as the production of liquid fuels or even in carbonated beverages and dry ice.  The new approach could eliminate the use of fossil fuels in the heating process, substituting electricity generated from renewable sources. 

The process looks to be scalable and represents a possible approach to greatly reducing one of the perhaps lesser known but nevertheless very significant sources of greenhouse gas emissions.

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New approach suggests path to emissions-free cement

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

Earth Wise is a production of WAMC Northeast Public Radio.

A New Low-Cost Battery

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Batteries have never been more important.  Not only do we all depend on cell phones, tablets and laptop computers that run on batteries, but two enormous industries are in major transitions that rely upon battery technology: personal transportation and the utility industry.   The electricity grid is increasingly turning to solar and wind power for generation and both will require effective energy storage if they are to truly become the predominant sources of electricity.

[Read more…] about A New Low-Cost Battery

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