Coffee is one of the most popular drinks worldwide; on average, 400 billion cups of coffee are consumed each year. As a result, approximately 18 million tonnes of coffee grounds are produced annually. Coffee grounds can be used for a variety of purposes. It can be used to fertilize your garden or added to compost. Coffee grounds can neutralize odors, can be used to exfoliate your skin, tenderize meats, and many other uses.
Despite all of these amazing uses for coffee grounds, the reality is that most of the coffee grounds produced actually end up in landfills; about 75% in fact. Rotting coffee grounds generate methane, a powerful greenhouse gas contributing to warming. Rotting coffee grounds also emit carbon dioxide, nitrous oxide, and ammonia. While there have been programs from coffee shops that will donate their coffee grounds to customers to use in their gardens (Starbucks has been part of the Grounds for Your Garden program since 1995), but most coffee shops are not implementing these initiatives.
Researchers from the Royal Melbourne Institute of Technology University in Australia have found a way to use coffee grounds on a larger scale and to eliminate the risk of them ending up in landfills. And that is to use coffee biochar concrete in the construction industry.
The researchers have developed concrete that is almost 30 percent stronger than traditional concrete by mixing in coffee-derived biochar. The coffee biochar was created using a low-energy process called pyrolysis. The organic waste is heated to 350 degrees Celsius without oxygen to avoid the risk of generating carbon dioxide. Under pyrolysis, organic molecules vibrate and break down into smaller components, creating biochar. This is a similar process that is used to roast unused beans to enhance their taste, except without the use of oxygen.
In coffee biochar concrete, about 15 percent of the sand they would use to make concrete is replaced with the coffee biochar, thus creating new concrete. The coffee biochar is finer than sand, and its porous qualities help to bind to organic material. Reducing the total use of sand in concrete will minimize the construction industry’s environmental footprint. It is said that over 50 billion metric tons of natural sand are used annually in construction. Sand mining significantly stresses ecosystems, including riverbeds and riverbanks, coffee biochar concrete can relieve some of that pressure on the environment.
The cement industry is the third largest source of industrial air pollution, including sulfur dioxide, nitrogen oxides, and carbon monoxide. Moreover, cement currently accounts for around 8% of global carbon dioxide emissions. Turning coffee- biochar into concrete will reduce the construction industry’s reliance on continuous mining of natural resources, making the industry more sustainable.
When introduced into concrete mixtures, the coffee biochar concrete was found to act as a microscopic carbon repository within the concrete matrix. The alkaline conditions within hardened concrete enable biochar to mineralize and firmly bind carbon dioxide into its structure over time. Concrete containing even a small percentage of spent coffee biochar was shown to sequester meaningful quantities of CO2 from the curing process and surrounding environment.
Utilizing waste coffee grounds to synthesize biochar for carbon sequestration could offer a sustainable way to offset concrete’s sizable carbon footprint while giving new purpose to spent grounds. With further research, coffee biochar concrete could provide a feasible carbon capture pathway for the construction industry.
The researchers estimate that if all the waste grounds produced in Australia annually could be converted into coffee biochar, it would amount to roughly 22,500 tonnes. Compare that to the 28 million tonnes of sand that are required to produce over 72 million tonnes of cement concrete in Australia. Just think: Australia has over 13 thousand coffee shops, whereas the United States has over 38 thousand coffee shops. If this project expands outside of Australia, coffee biochar concrete could significantly impact the environment and waste.
The research on coffee biochar concrete is still in the early stages; there is still a lot of testing to be done, but it shows that there are innovative and unique ways to reduce and repurpose organic landfill waste. Once the researchers can account for things like durability, the researchers will collaborate with local councils on future infrastructure projects, including the construction of walkways and pavements. Just think, we are one step closer to adding sustainability into the construction industry and one step closer to walking on coffee biochar concrete!
As urban air pollution increases globally, cities of all sizes are getting creative with technologies to literally filter out the smog. In 2017, China unveiled what it dubbed the “world’s biggest city air purifier” – a nearly 100-meter tall tower in northern China designed to reduce air pollution. While its effectiveness has limits, the towering structure demonstrates the growing interest in large-scale air filtration. Beyond this eye-catching prototype, cities worldwide are testing various innovative technologies to clean their skies.
In Xian in Shaanxi province, residents breathing some of China’s most polluted air are getting a reprieve thanks to their new neighbor – a 60-meter tall city air purifier tower. The structure’s interior has multiple filtration layers to catch particulates as air passes. An interior glass enclosure helps contain airflow so polluted air can fully pass through the system.
Since becoming operational in 2017, the city air purifier tower has noticeably cut harmful PM2.5 particles in the surrounding 2.6 square mile area. Cities like Xian regularly suffer from winter smog, blanketing entire regions. While not eliminating pollution, the tower provides cleaner air in its immediate vicinity.
The concept behind the city air purifier is similar to industrial scrubbers cleaning factory exhaust. Scaling up the technology, its designers hope such towers could eventually clean the air across entire cities. Of course, a limitation is that people must be close to the towers to benefit. And the structures are costly to build and operate. Still, China’s prototype tower has spurred interest in exploring larger-scale air filtration to supplement other anti-pollution measures.
While China goes big, other pollution fighters use buildings as filters. High-efficiency particulate air (HEPA) filtering systems installed in central air ventilation systems are increasingly common. HEPA filters use densely packed fibers to catch over 99% of particulates, pollen, and other pollutants. Similar city air purifiers at the street level are also possible. Smog halting benches designed in Paris contain a HEPA filter, sucking in air as pedestrians sit.
Living walls of plants built onto building exteriors also naturally filter gases. One study found adding 172 square feet of plants per person in London could remove all PM10 particulates. Mosses are especially effective pollutant absorbers.
Specialized building materials also react with and neutralize air pollutants when exposed to light. Concrete can be coated with titanium dioxide, which oxidizes nitrogen oxides and volatile organic compounds into safer compounds. Hydrophilic coatings help droplets absorb particulates.
Researchers are working on incorporating similar photocatalysts into road asphalt. These chemically treated roads could reduce tons of air pollutants daily if widely adopted.
Green algae may also hold the potential for clean city air through bioreactors. Experimental units in Hamburg use circulated airflow to filter exhaust fumes through an algae facade. The algae neutralize airborne pollutants while multiplying and producing biomass that can be harvested for biofuels.
What works in lab prototype city air purifiers, however, often proves challenging to execute citywide. Costs, aesthetics, and maintenance frequently impede adoption. Visible additions like green roofs require public acceptance. Passive approaches like photocatalytic paints, while hidden, need reapplication over time.
Scaling across metro areas also poses hurdles. Shanghai officials planned a network of small purifier towers across the city, but only a few ever materialized. Even proven concepts like roof gardens struggle to spread, as few developers want to trade rentable space for plants.
While technical solutions can filter pollution already in the air, reducing emissions at the source remains vital. You can’t plant your way out of bad air.
Despite obstacles, experts forecast continued innovation and cost reductions, improving feasibility. Market growth also brings economies of scale. Global green walls are forecast to be a $7.5 billion industry by 2030. Modular green facades and roofs can now be delivered as easy-install kits.
Policy measures like subsidies, tax incentives, and mandates will likely be needed, however, to spur mass adoption. Many cities now require mechanically ventilated buildings to install city air purifiers through filtration. While these are intended to protect building occupants from pathogens such as coronavirus, they also have the net effect of reducing particulate and other toxins from the air. Building codes could similarly require passive air-cleaning coatings and surfaces.
Though major pollution sources like autos require parallel efforts, creative technologies can help cities breathe easier. China’s massive air purifier may be just the start of a cleaner air movement. The scale of the air pollution crisis demands big, visible solutions to jolt public awareness.
While towering city air purifiers or algae bioreactors may capture headlines, addressing urban air pollution requires a multi-faceted approach. Technical fixes can target existing pollution, but cities must also prevent pollution at the source by transitioning to cleaner energy, transport, and waste systems.
Public awareness and policy measures are equally vital to drive large-scale adoption of innovative city air purifier concepts. Financial incentives, tax breaks, and inclusion in building codes could help technologies like photocatalytic coatings and surfaces become mainstream. Grassroots activism also plays a crucial role in keeping air quality high on urban agendas.
Though critical, bold engineering feats like China’s massive city air purifier tower should be viewed as supplementary elements of long-term solutions rather than silver bullet fixes. As much as cities need breathable air, those relying on singular grand gestures risk short-changing public health. Lasting solutions require a patient, systematic transition toward deeper sustainability.
Still, visionary projects like China’s offer hope by viscerally demonstrating the scale of what’s possible. Initial results and statements suggested the tower can produce over 10 million cubic meters of clean air daily. If we were to use this figure as a rough estimate, it would translate to about 3.65 trillion cubic meters of clean air annually, having a positive effect on the health of those living near it.
When paired with holistic strategies to address transport, energy, and waste systems, creative pollution mitigation technologies can steadily help clear the air. Cities have a responsibility to use every tool and innovation at their disposal to ensure citizens can simply breathe clean air.
An emerging application of 3D printing technology is fabricating entire homes through additive manufacturing. Early adopters demonstrate that 3D printing residential buildings carry significantly lower embedded carbon than conventional construction methods.
By optimizing materials and printing processes, 3D home printing could provide affordable, efficient, low-carbon housing to growing populations if adopted at scale.
Also known as additive manufacturing, 3D printing builds structures by depositing materials layer by layer according to digital models. Concrete is typically extruded through a moving print nozzle onto a substrate, hardening upon deposition to gradually form walls and roofs of low carbon 3D printed homes.
Companies pioneering low carbon 3D printed homes include Icon, SQ4D, and Mighty Buildings. Their printed concrete or polymer designs streamline manual labor of framing, insulation, and finishing. Architectural designs are also easier to customize versus cookie-cutter manufactured units.
But the sustainability benefits are among the most significant advantages over current construction. Architect Sam Ruben, an early adopter of 3D printing for eco-homes, states that 3D printing can reduce lifecycle emissions by over 50% compared to standard building techniques.
Part of the savings comes from more efficient material usage. Conventional construction methods are wasteful, generating excessive scrap materials that go to landfills—3D printing deposits only the needed amount layer-by-layer, eliminating waste.
Printing also allows easier integration of recycled components like crushed concrete aggregate into prints, diverting waste streams. And lightweight printed structures require less embedded energy to transport modules. Optimized print geometries better retain heat as well.
But the biggest factor is speed – printed homes can be move-in ready in days rather than weeks or months. A standard SQ4D home prints in just 8-12 hours of machine time. Accelerated production means less energy consumed over the total construction period.
And speed has financial benefits, too, reducing the logistical costs of prolonged projects. Combined with simplified labor, 3D printing can cut estimated construction expenses up to 30%. Those cost savings make printed homes more accessible to low-income groups while stimulating large-scale adoption.
To quantify benefits, Mighty Buildings completed a life cycle assessment comparing their printed composite polymer dwellings against conventional homes. They estimated their product cut emissions by over one-third during materials and construction. Waste production dropped by over 80%.
Such data helped the company achieve third-party verified EPD declarations certifying their low carbon 3D printed homes. Mighty Buildings believes printed homes could eliminate over 440 million tons of carbon emissions if comprising 40% of California’s housing needs by 2030.
Despite advantages, barriers remain to limit widespread 3D printed housing. Printed buildings still require finishing like plumbing, electrical, windows, and roofing. Developing integrated printing around and including those elements will maximize benefits.
High upfront printer costs also impede adoption, though expected to fall with scaling. And building codes need updates to cover novel printed structures despite proven duribility. Some jurisdictions like California are pioneering efforts to add low carbon 3D printed homes as approved models in housing codes.
But if technical and regulatory hurdles are resolved, additive construction could offer meaningful emissions cuts. With global populations projected to add 2 billion new urban dwellers by 2050, low carbon 3D printed homes may become a go-to sustainable building technique, especially in growing developing countries.
The urgent need for dense, low-carbon housing solutions to accommodate global populations makes 3D printing’s advantages stand out. Printed homes advance from gimmick to viable strategy against climate change.
Eco-conscious homebuyers on a budget have a new choice – low carbon 3D printed homes made from low-carbon cement. A new housing tract in Round Top, Texas has introduced small dwellings printed using concrete that produces just 8% of the carbon emissions of traditional Portland cement manufacturing.
Habitat for Humanity last year unveiled its first low carbon 3D printed home in Williamsburg, Virginia. The project represented Habitat for Humanity’s first completed 3D printed home in the country.
By combining 3D printing techniques with more sustainable cement mixtures, homebuilders can reduce the carbon footprints of affordable printed housing even further.
Mush-Rooms: Mycelium concrete (Myocrete) could revolutionize low-carbon building construction and provide another tool for building green.
A new paper published by the University of Newcastle has outlined a new method of creating a mycelium concrete construction material, with potentially far-reaching changes as a result.
The Need for Low-Carbon Building Materials
Concrete, by far, is the world’s most used building material. It is cheap, incredibly strong, and easy to manufacture. However, it carries costs elsewhere in our world.
The environmental impact of concrete manufacture, use, and transportation is incredibly high. Concrete production is responsible for 8% of all greenhouse gases worldwide, making it the second largest source of greenhouse gas emissions. Natural materials like mycelium concrete (myocrete) might be part of the answer.
Burning fossil fuels creates most of these greenhouse gases to heat the enormous kilns used to create concrete. As well as that, there are the negative effects of mining the sand and gravel required to create concrete, which disturbs the environment and destroys natural ecosystems.
There is also the fact that concrete production requires massive amounts of water, which puts a strain on communities and areas already in need.
There have been some developments to make concrete less environmentally damaging, such as improving the efficiency of kilns so they don’t require as much heat; however, by and large, concrete production and use have been disastrous for our world.
Nevertheless, new developments have been underway to replace this widely used building material, such as mass timber. However, a unique and potentially revolutionary new material could be just around the corner, and it’s something that you’re probably more used to seeing on your plate than in your buildings.
Mushrooms in Our Walls
Mycelium-based construction material research, including mycelium concrete, has been underway for several years, as the effects of concrete production have been well-documented for decades. However, so far, the ability to scale and use mycelium in construction has been limited by the available technology and methods.
Currently, the method used in creating mycelium-derived construction materials is by filling a rigid mold with a mixture of mycelium and a food source such as grain for the mycelium. This method can produce rigid shapes, such as bricks, which can be used in construction.
However, there are limitations to the usability of these materials. For one, the strength required to compete with concrete isn’t there, and the rigid mold limits the variety of shapes and structures.
A new method created at the University of Newcastle, dubbed mycocrete (mycelium concrete), could completely change this and how construction has been done. The way mycocrete works is similar to past methods, with some distinctions.
One of them is in the mold that the paste is put into; where previous methods used rigid molds, mycocrete uses a permeable knitted mold that facilitates the growth of the mycelium by the amount of oxygen available. This flexible mold also allows the mycelium to grow in shapes that otherwise would be impossible with a rigid mold.
The process works by filling the knitted mold with a mixture of mycelium, paper powder, paper fiber clumps, water, glycerin, and xanthan gum. This is then hung up in a dark, warm, humid environment to facilitate the mycelium’s growth.
The result is a mycelium-based material significantly stronger than conventional mycelium bricks, notably much stronger than the material created with rigid molds. This is due to the amount of oxygen the mycelium has access to, given the mold’s permeability.
Myocrete is Still in the Early Stages, Though
However, despite the team’s promising results at Newcastle, myocrete mycelium concrete based buildings are still quite far off.
While continuing to develop the mycelium compound is still of major importance, the main obstacle is the fact that the factories and industries that work with the construction industry will need to be re-tooled for mycelium concrete along with new installation equipment being implemented.
Nonetheless, they have created some interesting prototypes, including the “BioKnit” project. This project was created to demonstrate the use of alternative materials in solving conventional construction design problems.
The team created BioKnit as one piece to limit weak spots inherent in joinery. Dr. Jane Scott, the author of the corresponding paper, said, “Our ambition is to transform the look, feel, and well-being of architectural spaces using mycelium concrete in combination with biobased materials such as wool, sawdust, and cellulose.”
With the priority being placed on reducing the environmental impact of construction, this new method could completely change the way we live and the spaces we live inside.
The construction industry is very energy intensive. Steel and concrete, both popular materials in construction, are very carbon-intensive in their production. Many of the emissions from concrete production are attributed to burning fossil fuels such as oil and natural gas, which heat up the limestone and clay that becomes Portland cement. There is an opportunity for the construction industry to shape a nature-positive economy from the city to the building design and material and component levels.
The Mobius Project, a greenhouse designed by Iguana Architects, uses biomimicry in sustainable design by drawing inspiration from how ecosystems in nature work. They are committed to revolutionizing food production by turning waste into locally grown, low-carbon nutritious food. The biological waste can also be turned into methane to generate electricity for the greenhouse. In their closed cycle with zero waste, one organism’s waste becomes the next’s input. The idea for the Mobius Project came from observing the oak tree, which has the potential to reuse its output resources, including materials, energy and water.
The Eden Project, designed by exploration architecture, uses biomimicry in sustainable design with a giant greenhouse inspired by the biblical Garden of Eden. It was designed to resemble soap bubbles, carbon molecules, and radiolaria. The idea was that the soap bubbles would be optimally positioned in the sun to allow for complete self-healing. They also took inspiration from dragonfly wings for the best way to assemble steel pieces, allowing for a lightweight structure that required fewer carbon emissions to transport from place to place.
Designers have also looked at lotus leaves to decrease the need for protective finishings, which are usually toxic. The lotus leaf has tiny hairs covered with a waxy coating that allows it to stay dry. Water that hits the leaf will roll off the waxy nonpolar coating. This has inspired a protective coating for external areas that will repel water and dirt, which reduces the need for maintenance. Moreover, reducing the water accumulation in buildings will reduce deterioration mechanisms in infrastructures, such as steel corrosion, sulphate attacks, freezing and thawing.
Limestone-producing bacteria can be used to extend a building’s lifespan. Certain bacteria can produce limestone, filling the gaps and cracks that affect concrete structures over time. This can reduce the need to use new concrete for repairs.
Learning from nature and imputing the way nature works into our designs and in the construction industry can make our built environments more sustainable. There’s so much we can learn from nature; the more we discover, the more we can work toward reducing our impact on the planet.
War is hell. This sentiment has been repeated throughout human history as the devastation and destruction of countries and communities it causes is incalculable. Syria is a prime example of how civil or otherwise war can destroy a society and its infrastructure.
The war began in the context of high youth unemployment, drought, a one-party dictatorship that crushed basic human freedoms and dignity, and extreme wealth inequality. It was a surprise to no one that in 2011, insurgency by oppressed groups in the region began in earnest, spiralling Syria into a conflict that continues to this day with no end in sight. The devastation this war has brought has caused 5.7 million people to flee the country due to the risk that the war has brought to their lives.
The war destroyed 130,000 buildings, many of these the homes of everyday people and their businesses. All this destruction is horrible, and as if they hadn’t experienced enough of it, Syria fell victim to a 7.7 Richter earthquake in February, expanding the damage even further. However, despite all this horrific destruction, serious efforts have been made to expedite the recovery and reconstruction of this battered country. 70% of the 130,000 buildings destroyed were made of reinforced concrete. Scientists have discovered that they can use a significant amount of this rubble to create new concrete, recycling what is there and saving costs compared to importing new concrete.
The study led by Professor Abdulkader Rashwani proved that recycled concrete made from the rubble of old buildings doesn’t significantly impact the mechanical performance of the new concrete. This is the first time recycled concrete has been proven to do this, as other attempts in other countries have been made. Still, due to the disparity in methods of manufacture, mechanical performance hasn’t been guaranteed. When people return, they will want to rebuild the buildings that had been destroyed.
Transportation of raw materials is one of the highest costs, and aggregate being increasingly scarce makes recycling existing materials necessary. This recycled concrete is made by crushing the rubble, removing any steel or textiles, and washing the resulting aggregate. The fine material washed out is sand and cement, and it is also being studied to determine if it can be reused.
The material was then tested for tensile and compressive strength and how much water, co2, and chlorine were absorbed. The concrete passed all of the tests, and now the protocol stands as a model for other war-torn or earthquake-damaged countries to rebuild their cities and communities. In an interview with the Guardian, Professor Rashwani said, “It was our duty to help the people there, a lot of people needed our help, so we went there and forgot about all the bad consequences. We have now started to go to some local councils and help them to put some plans in place for the future. We can at least try to make this region safer and give people some hope.”
The costs of war and conflict between nations and nations between people are often horrendous and often borne by the innocent. Most of the buildings destroyed in the fighting were homes of families and individuals who had nothing to do with the war. Yet still, they are left without homes in their home countries. Having a plan with new methods to guarantee quick reconstruction of these buildings is crucial.
The added benefit of this research is that it is a model that can be applied in other places outside Syria. Syria is simply one country at war right now, and if the path of human history indicates what’s to come, it won’t be the last one either. This research is invaluable for the everyday people ravaged by conflict or disaster, now and in the future.
3D printed concrete may lead to a shift in architecture and construction. Because it can be used to produce new shapes and forms that current technologies struggle with, it may change the centuries-old processes and procedures that are still used to construct buildings, resulting in lower costs and saved time.
However, concrete has a significant environmental impact. Vast quantities of natural sand are currently used to meet the world’s insatiable appetite for concrete, at great cost to the environment. In general, the construction industry struggles with sustainability. It creates around 35% of all landfill waste globally.
Our new research suggests a way to curb this impact. We have trialled using recycled glass as a component of concrete for 3D printing.
Concrete is made of a mix of cement, water, and aggregates such as sand. We trialled replacing up to 100% of the aggregate in the mix with glass. Simply put, glass is produced from sand, is easy to recycle, and can be used to make concrete without any complex processing.
Demand from the construction industry could also help ensure glass is recycled. In 2018 in the US only a quarter of glass was recycled, with more than half going to landfill.
Building better
We used brown soda-lime beverage glass obtained from a local recycling company. The glass bottles were first crushed using a crushing machine and then the crushed pieces were washed, dried, milled, and sieved. The resulting particles were smaller than a millimetre square.
The crushed glass was then used to make concrete in the same way that sand would be. We used this concrete to 3D print wall elements and prefabricated building blocks that could be fitted together to make a whole building.
A building envelope prefabricated using the 3D printing process. Mehdi Chougan, Author provided
If used in this way, waste glass can find a new life as part of a construction material.
The presence of glass does not only solve the problem of waste but also contributes to the development of a concrete with superior properties than that containing natural sand.
The thermal conductivity of soda-lime glass – the most common type of glass, which you find in windows and bottles – is more than three times lower than that of quartz aggregate, which is used extensively in concrete. This means that concrete containing recycled glass has better insulation properties. They could substantially decrease the costs required for cooling or heating during summer or winter.
Improving sustainability
We also made other changes to the concrete mixture in order to make it more sustainable as a building material, including replacing some of the Portland cement with limestone powder.
Portland cement is a key component of concrete, used to bind the other ingredients together into a mix that will harden. However, the production of ordinary Portland cement leads to the release of significant amounts of carbon dioxide as well as other greenhouse gases. The cement production industry accounts for around 8% of all carbon dioxide emissions in the environment.
Limestone is less hazardous and has less environmental impact during the its production process than Portland cement. It can be used instead of ordinary Portland cement in concrete for 3D printing without a reduction in the quality of the printing mixture.
3D printed layers of a wall element. Mehdi Chougan, Author provided
We also added lightweight fillers, made from tiny hollow thermoplastic spheres, to reduce the density of the concrete. This changed the thermal conductivity of the concrete, reducing it by up to 40% when compared with other concrete used for 3D printing. This further improved the insulation properties of the concrete, and reduced the amount of raw material required.
Using 3D printing technology, we can simply develop a wall structure on a computer, convert it to simple code and send it to a 3D printer to be constructed. 3D printers can operate for 24 hours a day, decrease the amount of waste produced, as well as increase the safety of construction workers.
Our research shows that an ultra-lightweight, well insulated 3D building is possible – something that could be a vital step on our mission towards net zero.
As pressure ramps-up to drastically shrink the carbon footprint of the world’s cities, developers and architects have been tinkering with the recipe for the type of materials that goes into a building. City-planners are banking on technology to make cheaper and greener steel and concrete, to drive down the hefty emissions of built infrastructure.
Building and construction are responsible for 39 per cent of all carbon emissions in the world, according to the International Energy Agency. Concrete, the primary component for most built infrastructure, is responsible for a huge amount of greenhouse gas emissions. The five billion tonnes of cement produced each year account for eight per cent of the world’s man-made carbon dioxide emissions. It would rank third for its emissions if it was a country. Then there is steel — whose production accounts for around seven per cent of the world’s greenhouse gas emissions.
As countries look to slash their emissions, hard-to-abate sectors like construction are facing more heat with governments joining hands and forming coalitions to signal that, moving forward, they will shift to buy low-carbon steel and concrete for public construction.
At the COP26 landmark climate summit in Glasgow, the governments of the United Kingdom, India, Germany, Canada and the United Arab Emirates (UAE), under a new coalition named the Industrial Deep Decarbonisation Initiative (IDDI), pledged to support the use of low-carbon materials in building construction. “If you make it, we will buy it,” said the five nations in a statement.
The member governments of the IDDI plan to reveal interim targets by mid-2022, to better align their procurement plans with new net-zero goals for the public construction sector. The pledge also includes requirements for members to disclose the carbon embodied in major public construction projects by 2025, said the UK COP presidency in a press release.
Within the next three years, the IDDI aims to have at least 10 countries commit to purchasing low-carbon concrete and steel.
Large steelmakers clean up their act
The public procurement of steel and concrete in the five nations currently represents between 25 to 40 per cent of the domestic market for such materials. Industry stakeholders said that the pledge is a clear market signal from some of the world’s largest steel and concrete buyers believing that it will create green demand across the supply chains of the building sector.
China, India and Japan are the world’s top steel producing countries. Image: World Steel Association
“Global construction accounts for 39 per cent of total global emissions, with buildings equivalent to the size of Paris being built every week. There is now a critical and narrow window for sector transformation,” said Jo da Silva, global director of sustainable development at Arup, a London-based engineering, architecture and city planning consultancy.
“Governments need to make companies feel confident about investing now in the processes of making low-carbon steel and concrete,” she said.
China, the world’s largest steel and concrete producer, is missing from the IDDI list. However, its top steelmaker, the China Baowu Steel Group Corp., formed its own global alliance with other steel producers last Thursday, in a bid to gather resources and exchange information in the development of low-carbon metallurgical technology.
Known as the Global Low-Carbon Metallurgical Innovation Alliance, it has more than 60 members from 15 countries. These include leading global steelmakers and mining enterprises such as Luxembourg-based ArcelorMittal, German conglomerate Thyssenkrupp and Melbourne’s BHP Group. About 20 Chinese steel companies are also part of the alliance.
Baowu has committed to carbon neutrality by 2050, a decade earlier than the Chinese government’s national target.
China’s Baowu Steel Group Corp., the world’s largest steelmaker, initiated the formation of a global alliance of steel producers last Thursday, in a bid to gather resources and exchange information in the development of low-carbon metallurgical technology. [Click to enlarge] Image: World Steel Association
Neil Martin, chief executive for property developer Lendlease’s European business, told Eco-Business that the commitment from steel producers and national authorities to seize decarbonisation opportunities is a potential game-changer for the building sector.
Need for sharper approach on embodied carbon
Lendlease currently uses a large amount of steel – what amounts to a volume sufficient for the building of 60 Eiffel Towers per annum – for its global projects. Substituting the material will make a difference for the environment, given how dirty the steel industry is.
The developer targets to be completely net zero by 2040.
“Property developers have made progress in reducing the operational carbon emissions of buildings, but here’s the rub: almost 90 per cent of building emissions are Scope 3 – indirect emissions from the production of building materials along the value chain. We still have to buy a lot of steel, concrete, aluminium and glass, but we do not have control over their production and supply lines,” said Martin.
Currently, much of the push towards greener buildings is devoted to minimising the energy needed to keep them running, but the situation is changing. During COP26, architects, mayors and property developers have been calling for green building certifications that take embodied emissions from materials into account in order to meet net-zero carbon goals.
Traditionally, steel is made by heating and melting iron ore in a blast furnace at high temperature. A by-product of the chemical reaction that takes place is carbon dioxide. Now, there are several other production methods that are cleaner, involving renewables and green hydrogen. These processes, however, are at various stages of development.
Professor Lam Khee Poh, dean of the National University of Singapore’s School of Design and Environment, and its Provost’s Chair Professor of Architecture and Building, said that strong signalling from national actors to industry matters and governments need to go beyond changing their public procurement models.
We need not and should not regard our predominantly steel and concrete jungles as the norm for cities.
Professor Lam Khee Poh, Dean of NUS School of Design and Environment, Singapore
“It is not just that the public sector is often a major customer. Yes, there are economies of scale to be gained, but more importantly, the demonstration of leadership from governments has an impact on the enactment of building codes and standards that will pave the way for a green transition,” he said.
Lam, a strong advocate for net-zero cities, said that building industries around the world typically work to existing regulations and only a handful will adopt voluntary standards to advance the field.
According to COP26 reports, between 2015 and 2020, 19 additional countries have building energy codes in place. However, most construction will still take place in countries without such codes.
“The building sector has historically been fragmented. It will take a revolutionary effort to develop a broadly accepted and comprehensive method of calculating embodied carbon that can be effectively and efficiently implemented in the design process for change to happen,” Lam said.
Better pricing for low-carbon building materials
In Southeast Asia, there is also a need to overcome the biased perception that concrete is cheap, which leads to the inertia to replace concrete use in buildings. The low cost of concrete is mainly due to the use of cheap labour in developing countries, and does not take into account the spillover costs when the production of concrete creates externalities – negative impacts on the environment, said Lam.
Referring to a recently-published McKinsey report, Lam argued that products such as carbon-cured concrete, if positioned differently, can potentially give companies an edge among environmentally conscious buyers and greater pricing power.
Timber as an alternative material should be considered too, especially for tropical cities. “We need not and should not regard our predominantly steel and concrete jungles as the norm for cities,” he said.
Yvonne Soh, executive director of the Singapore Green Building Council, told Eco-Business that the council has recently observed that there is no cost premium for using greener concrete in buildings in Singapore, based on current standards.
Soh also noted that lower-carbon options, whether concrete or steel, are already available.
“In fact, there is a lot of interest among private sector players and many are ready to take the leap to try out new materials. We do not have a lack of willing early adopters,” she said. “The key issue is regulatory barriers, because there are basic safety requirements governing the usage of structural materials in a building.”
“Building professionals must also be comfortable with using the material,” she said, drawing parallels to how governments have educated the public on the safety of the Covid-19 vaccines before they pushed for widespread adoption. “It’s not just about sticking some wallpaper on the wall. We have to ensure that [the use of low-carbon materials] does not compromise the building’s structural safety.”
The Singapore Green Building Council now conducts courses on sustainable supply chains for buildings, to encourage firms and stakeholders in the built environment sector to address environmental gaps in their sourcing and reporting. The council also initiated a pledge for the built environment industry to act on embodied carbon. As of November 2021, more than 75 organisations have signed up.
A time-travelling Victorian stumbling upon a modern building site could largely get right to work, says Chris Thompson, managing director of Citu, which specialises in building low-carbon homes.
That’s because many of the materials and tools would be familiar to him.
The Victorian builder would certainly recognise concrete, which has been around for a long time.
The world’s largest unreinforced concrete dome remains the one at Rome’s Pantheon, which is almost 2,000 years old. The Colosseum is largely concrete too.
Today we use more concrete than any substance, other than water.
That means it accounts for about 8% of the carbon dioxide (CO2) we emit into the atmosphere. That is substantially more than the aviation industry, which makes up about 2.5% of emissions.
The Pantheon in Rome – almost 2,000 years old and built from concrete. GETTY IMAGES
But some companies are developing concrete that has a much lower CO2 impact.
Citu is building its headquarters in Leeds from a new low-carbon concrete that it says cuts CO2 emissions by 50% compared to traditional concrete.
It has used 70 cubic metres of it for the building’s foundations.
Some buildings, like this one in Mexico, are being constructed using Cemex’s low-carbon concrete. CEMEX
This concrete, released last year by Mexico’s Cemex under the label Vertua, is one of a series of recent developments helping pave the way to greener concrete.
Making cement, which makes up 10-15% of concrete, is a carbon-intensive process. Limestone has to be heated to 1,450C, which normally requires energy from fossil fuels and accounts for 40% of concrete’s CO2.
This separates calcium oxide (which you want) from carbon dioxide (which is the problem).
This calcium oxide reacts further to form cement. Grind some into powder, add some sand, gravel and water, and it forms interlocking crystals.
Voilà, concrete.
So how can you do all this without releasing so much CO2?
Karen Scrivener has been working on a way to replace some of the cement in concrete. EPFL
One way is by replacing much of the conventional cement with heated clay and unburnt limestone, says Karen Scrivener, a British academic and head of the construction materials laboratory at Switzerland’s Ecole Polytechnique Fédérale de Lausanne.
For a long time, people (think, Romans) knew you could substitute some of the cement with ash from burning coal (or volcanoes). Or more recently, slag from blast furnaces. This even improved concrete’s strength and durability.
Prof Scrivener was approached by Prof Fernando Martirena from Cuba, who thought it might be possible to use clay in the production of concrete.
So together they worked out a way to replace a really big chunk of conventional cement, and produce equally strong concrete.
Not only would that mean 40% less CO2, it also works with existing equipment, according to Prof Scrivener.
And that’s crucial for a material that has to be competitively priced.
Two companies last year began commercially cooking up this product, called LC3 (for limestone calcined clay cement).
“I reckon next year about 10 plants are going into operation, and really we can see an exponential take-off after that,” she says.
A further 10-20% savings on CO2 emissions can come from finding new ways of making cement more reactive, she adds.
Often people pour in more cement than they actually need, to get early strength.
But if you put in very tiny amounts of other minerals instead, that seems to increase the reactivity too, she says.
Another approach is just coming up with an utterly different way to clench the sand and stone particles together, without cooking limestone into calcium oxide.
This is what Vertua does, says Davide Zampini, head of research for Cemex, the world’s second biggest building materials business.
“It’s a binder that’s rich in aluminosilicates (minerals made from aluminium and silicon), and we have produced chemicals to activate those, and go through a reaction called geopolymerisation,” he explains.
This forms a 3D network of molecules, and a solid binder to grip sand and stone in place.
But it’s not as cheap as conventional concrete, admits Dr Zampini.
You have to find a customer who is really keen on significantly reducing the CO2 footprint of their buildings, he says, like Citu in Leeds.
Cement firms are experimenting with towers like this one which catch the CO2. LEILAC
A third approach is using a big steel tube, says Daniel Rennie, co-ordinator of a project called LEILAC (Low Emissions Intensity Lime and Cement).
It’s 60m (197ft) tall. You can add it to an existing cement plant.
You “chuck materials down from the top” and it gently floats down the tube, which is heated from the outside.
As CO2 comes off the particles, “we just capture it at the top, the calcium oxide continues to the bottom and continues its journey in the cement-making process,” he says.
The project is run by Calix, an Australian company that makes environmentally sustainable technology for industry.
Once captured by the tower the CO2 is compressed and stored in an empty oil reservoir. LEILAC
The company had been thinking about how to decarbonise another building material.
“And just, the penny dropped, and we could apply this to cement,” Mr Rennie says.
A little pilot tower, built in 2019, is now accounting for 5% of production at Heidelberg Cement’s Lixhe plant in Belgium.
This is capturing about 25,000 tonnes a year of CO2.
In Germany, they’re building one at another Heidelberg plant in Hanover, where 20% of total production will go through the new process, capturing about 100,000 tonnes of CO2 a year.
Once captured, the CO2 is compressed, shipped in a barge to Norway, and stored in an empty oil reservoir under the North Sea.
Normally “90% of the cost is capturing the carbon”, so this just leaves the cost of transport and storage.
Innovations that were just ideas 20 years ago are now taking hold in the concrete industry, says Claude Loréa. JOHNNY BLACK
“I’ve been in this industry 20 years, and I really see a big change,” says Claude Loréa, cement director from the Global Cement and Concrete Association.
“Stuff we dreamed about 20 years ago is now coming through,” she adds.
And cement makers have already reduced their carbon emissions “almost by 20% since 1990”, she says, largely by making kilns more energy-efficient.
Still, while we can probably get overall CO2 emissions down by 60-80%, we’ll still end up with some we’ll need to capture and store, says Prof Scrivener.
Also, there’s no point looking for intricate solutions that can just be used in “some very sophisticated factories in the US”, she says.
Around 90% of future cement production will take place outside the wealthy OECD countries.
A concrete path to cutting concrete’s carbon emissions needs alternatives that will work well and cheaply for the coming building booms in India and Africa.
Concrete may have been born in Rome and Britain.
But China made more concrete between 2011 and 2013 than the US did in the whole 20th Century.
By Padraig Belton – Technology of Business reporter
