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Tag: low-carbon concrete

Technology Helps City Air Purifiers Run at Scale

Posted on by dishanth
Technology Helps City Air Purifiers Run at Scale

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.

 

 

 

 

Source  Happy Eco News

Low Carbon 3D Printed Homes – Lower Cost too

Posted on by dishanth
Low Carbon 3D Printed Homes – Lower Cost too

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.

 

 

 

 

 

 

Source  Happy Eco News

Mush-Rooms: How Mycelium Concrete Could Revolutionize Building Construction

Posted on by dishanth
Mush-Rooms: How Mycelium Concrete Could Revolutionize Building Construction

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.

 

 

 

 

Source Happy Eco News

Researchers In Syria Have Discovered Concrete Recycling Method

Posted on by dishanth
Researchers In Syria Have Discovered Concrete Recycling Method

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.

 

 

 

 

Source Happy Eco News

Building’s hard problem – making concrete green

Posted on by dishanth
Building’s hard problem – making concrete green

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.

 

GETTY IMAGES
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

Source BBC