Having a Break


Every so often I get to the point where I feel I just need a break from Blogging and the like, to rest, to regroup, to recharge and to catch-up on work requirements – so that is what I am currently doing. I am physically exhausted at the moment and that often brings on more serious issues with my health (which I am beginning to sense), so the wiser course is to rest for a little – to just ease off for a bit, take the foot of the throttle, etc. So I am taking a break for a bit – I think I’m about 2, 3 or 4 days into it at the moment and when I return it will be a gradual return, not an all in and at it approach.

How long will the break be? That I’m not sure about – there are some pressing issues around my work at the moment, some medical appointments, etc – and these all over the next week or so – which also means the break will be less of a break and more of a short-term refocus I suppose. I don’t expect it to be more than 2 weeks, probably less.

New report shows the world is awash with fossil fuels. It’s time to cut off supply



Australia’s coal production is expected to jump by 34% to 2030, undercutting our climate efforts.
Nikki Short/AAP

Peter Christoff, University of Melbourne

A new United Nations report shows the world’s major fossil fuel producing countries, including Australia, plan to dig up far more coal, oil and gas than can be burned if the world is to prevent serious harm from climate change.

The report found fossil fuel production in 2030 is on track to be 50% more than is consistent with the 2℃ warming limit agreed under the Paris climate agreement. Production is set to be 120% more than is consistent with holding warming to 1.5℃ – the ambitious end of the Paris goals.

Australia is strongly implicated in these findings. In the same decade we are supposed to be cutting emissions under the Paris goals, our coal production is set to increase by 34%. This trend is undercutting our success in renewables deployment and mitigation elsewhere.


productiongap.org

Mind the production gap

The United Nations Environment Program’s Production Gap report, to which I contributed, is the first to assess whether current and projected fossil fuel extraction is consistent with meeting the Paris goals.

It reviewed seven top fossil fuel producers (China, the United States, Russia, India, Australia, Indonesia, and Canada) and three significant producers with strong climate ambitions (Germany, Norway, and the UK).




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The production gap is largest for coal, of which Australia is the world’s biggest exporter. By 2030, countries plan to produce 150% more coal than is consistent with a 2℃ pathway, and 280% more than is consistent with a 1.5℃ pathway.

The gap is also substantial for oil and gas. Countries are projected to produce 43% more oil and 47% more gas by 2040 than is consistent with a 2℃ pathway.


productiongap.org

Keeping bad company

Nine countries, including Australia, are responsible for more than two-thirds of fossil fuel carbon emissions – a calculation based on how much fuel nations extract, regardless of where it is burned.

China is the world’s largest coal producer, accounting for nearly half of global production in 2017. The US produces more oil and gas than any other country and is the second-largest producer of coal.

Australia is the sixth-largest extractor of fossil fuels , the world’s leading exporter of coal, and the second-largest exporter of liquefied natural gas.




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Prospects for improvement are poor. As countries continue to invest in fossil fuel infrastructure, this “locks in” future coal, oil and gas use.

US oil and gas production are each projected to increase by 30% to 2030, as is Canada’s oil production.

Australia’s coal production is projected to jump by 34%, the report says. Proposed large coal mines and ports, if completed, would represent one of the world’s largest fossil fuel expansions – around 300 megatonnes of extra coal capacity each year.


productiongap.org

The expansion is underpinned by a combination of ambitious national plans, government subsidies to producers and other public finance.

In Australia, tax-based fossil fuel subsidies total more than A$12 billion each year. Governments also encourage coal production by fast-tracking approvals, constructing roads and reducing royalty requirements, such as for Adani’s recently approved Carmichael coal mine in the Galilee Basin.

Ongoing global production loads the energy market with cheap fossil fuels – often artificially cheapened by government subsidies. This greatly slows the transition to renewables by distorting markets, locking in investment and deepening community dependency on related employment.

In Australia, this policy failure is driven by deliberate political avoidance of our national responsibilities for the harm caused by our exports. There are good grounds for arguing this breaches our moral and legal obligations under the United Nations climate treaty.

Protestors locked themselves to heavy machinery to protest the Adani coal mine in central Queensland.
Frontline Action on Coal

Cutting off supply

So what to do about it? As our report states, governments frequently recognise that simultaneously tackling supply and demand for a product is the best way to limit its use.

For decades, efforts to reduce greenhouse gas emissions have focused almost solely on decreasing demand for fossil fuels, and their consumption – through energy efficiency, deployment of renewable technologies and carbon pricing – rather than slowing supply.

While the emphasis on demand is important, policies and actions to reduce fossil fuels use have not been sufficient.

It is now essential we address supply, by introducing measures to avoid carbon lock-in, limit financial risks to lenders and governments, promote policy coherence and end government dependency on fossil fuel-related revenues.

Policy options include ending fossil fuel subsidies and taxing production and export. Government can use regulation to limit extraction and set goals to wind it down, while offering support for workers and communities in the transition.




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Several governments have already restricted fossil fuel production. France, Denmark and New Zealand have partially or totally banned or suspended oil and gas exploration and extraction, and Germany and Spain are phasing out coal mining.

Australia is clearly a major contributor in the world’s fossil fuel supply problem. We must urgently set targets, and take actions, that align our future fossil fuel production with global climate goals.The Conversation

Peter Christoff, Associate Professor, School of Geography, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Enough ambition (and hydrogen) could get Australia to 200% renewable energy



Hydrogen infrastructure in the right places is key to a cleaner, cheaper energy future.
ARENA

Scott Hamilton, University of Melbourne; Changlong Wang, University of Melbourne; Falko Ueckerdt, Potsdam Institute for Climate Impact Research, and Roger Dargaville, Monash University

The possibilities presented by hydrogen are the subject of excited discussion across the world – and across Australia’s political divide, notoriously at war over energy policy.




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On Friday Australia’s chief scientist Alan Finkel will present a national strategy on hydrogen to state, territory and federal energy ministers. Finkel is expected to outline a plan that prioritises hydrogen exports as a profitable way to reduce emissions.

It is to be hoped the strategy is aggressive, rather than timid. Ambition is key in lowering the cost of energy. Australia would do better aiming for 200% renewable energy or more.

It’s likely the national strategy will feature demonstration projects to test the feasibility of new technology, reduce costs, and find ways to share the risk of infrastructure investment between government and industry.

There are still a number of barriers. Existing gas pipelines could be used to transport hydrogen to end-users but current laws are prohibitive, mechanisms like “certificates of origin” are required, and there are still key technology issues, particularly the cost of electrolysis.

These issues raise questions of what a major hydrogen economy really looks like. It may prompt suspicions this is just the a latest energy pipe dream. But our research at the Australian-German Energy Transition Hub argues that an ambitious approach is better than a cautious one.

Aggressively pursing hydrogen exports will reduce costs of domestic energy supply and provide a basis for new export industries, such as greens steel, in a carbon-constrained world.




Read more:
Making Australia a renewable energy exporting superpower


Optimal systems cost less

We used optimisation modelling to examine how a major hydrogen industry might roll out in Australia. We wanted to identify where major plants for electrolysis could be built, asked whether the existing national electricity market should supply the power, and looked at the effect on the cost of the system and, ultimately, energy affordability.

Australian Hydrogen export locations.

Our results show the locations for future hydrogen infrastructure investment will be mainly determined by their capital costs, the share of wind and solar generation and the capacity of electrolysers to responsively provide energy to the system, and the magnitude of hydrogen production.




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How hydrogen power can help us cut emissions, boost exports, and even drive further between refills


We also identified potential demonstration projects across Australia, such as:

  • large-scale production of liquid hydrogen and export from the Pilbara in Western Australia
  • hydrogen to support steel manufacturing in South Australia
  • injecting hydrogen into the gas networks in Victoria and support industry and electricity generation
  • hydrogen to supply transport fuel for major users such as trucks, buses and ferries in New South Wales, and
  • hydrogen to produce ammonia at an existing plant in Queensland.

An export-oriented economy

If we assume electrolysers remain expensive, around A$1,800 per kilowatt, and need to run at close to full-load capacity all the time, the result is large hydrogen exporting hubs across the country, built near high quality solar and wind power resources. Ideal locations tend to be remote from the national energy grid, such as in Western Australia and Northern Territory, or at relatively small-scale in South Australia or Tasmania.

There is much debate around the current cost of electrolysis, but consensus holds that economies of scale will substantially reduce these costs – by as much as an order of magnitude. This is akin to the cost reductions we have seen in solar power and batteries.

200 per cent renewables scenario

This infrastructure requires some major investment. However, our modelling shows that if Australia produces 200% of our energy needs by 2050, exporting the surplus, we see major drops in system costs and lower costs of energy for all Australia. If Australia can produce 400 Terrawatt-hours of hydrogen energy for export, modelling results show the average energy cost could be reduced by more than 30%.

Hydrogen ambition reduces costs of electricity supply.

The driving factor is our level of ambition. The more we lean into decarbonising our economy with green energy, the further the costs fall. The savings from the integrated and optimised use of electrolysers in a renewable-heavy national electricity market outweigh the cost of building large renewable resources in remote locations.

A large hydrogen export industry could generate both substantial export revenue and substantial benefits to the domestic economy.

Hydrogen export economy versus true RE economy

To sum up, the picture above shows two possible hydrogen futures for Australia.

In the first, Australia lacks climate actions and electrolyser costs remain high with limited economies of scale, and we export from key remote hubs such as the Pilbara.




Read more:
We need a national renewables approach, or some states – like NSW – will miss out


In the other, ambition increases and costs drop, and the hydrogen export industry connects to the national grid, providing both renewable exports and benefits to the grid. This also promotes the use of hydrogen in the domestic market. Australia embraces a true renewable economy and a new chapter of major energy exports begins.

Either way, Australia is primed to become a hydrogen exporting superpower.The Conversation

Scott Hamilton, Strategic Advisory Panel Member, Australian-German Energy Transition Hub, University of Melbourne; Changlong Wang, Researcher, The Energy Transition Hub, University of Melbourne; Falko Ueckerdt, , Potsdam Institute for Climate Impact Research, and Roger Dargaville, Senior lecturer, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change will make fire storms more likely in southeastern Australia


Giovanni Di Virgilio, UNSW; Andrew Dowdy, Australian Bureau of Meteorology; Jason Evans, UNSW; Jason Sharples, UNSW, and Rick McRae, ACT Emergency Services Agency

Temperatures across many regions of Australia are set to exceed 40℃ this week, including heatwaves forecast throughout parts of eastern Australia, raising the spectre of more devastating bushfires.

We have already heard warnings this fire season of the possibility of firestorms, created when extreme fires in the right conditions form their own weather systems.




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Firestorms and flaming tornadoes: how bushfires create their own ferocious weather systems


Firestorms are the common term for pyrocumulonimbus bushfires – fires so intense they create their own thunderstorms, extreme winds, black hail, and lightning.

While they are very rare, our research published earlier this year, found climate change is making it likely they will become more common in parts of southeast Australia.

We also identified certain regions in southern and eastern Australia, including near Melbourne’s fringe, that in the second half of this century will be far more vulnerable to these events than others.

How firestorms happen

The 2003 Canberra bushfires, devastating on a grand scale, saw a Canberra resident film a fire tornado for the first time ever. Six years later, the ferocious Black Saturday bushfires in Victoria created three separate pyrocumulonimbus events.

More recently, fire storms devastated California in November 2018.

Pyrocumulonimbus events begin with the intense heat of a very big and fast-burning wildfire, which causes a large and rapidly rising smoke plume. As the plume rises, low atmospheric pressure causes it to expand and cool. Moisture can condense into a type of cloud known as a pyrocumulus – not pyrocumulonimbus, yet. This type of cloud can be common in large fires.

However, with the right environmental conditions the plume goes much higher and pyrocumulonimbus clouds can form, towering up to 15km in some cases. As it rises, the plume cools, and the upper part of the clouds form ice particles that collide and can produce lightning.

These thunderstorms can create erratic and dangerously strong wind gusts. These can drive blizzards of embers that ignite spot fires beyond the fire font.

Lightning from the plume can start new fires, well ahead of the main fire. In one case, lightning generated in a pyrocumulonimbus cloud has been recorded starting new fires up to 100km ahead of the main fire.

How climate change makes firestorms more likely

One of the key elements to a firestorm forming is the precondition of the atmosphere above it. We wanted to investigate how a changing climate might affect the likelihood of firestorms happening.

Previous research has found there is more dynamic interaction between a large fire and the atmosphere when the air about 1.5km above the surface is relatively dry, and when there are larger temperature differences across increasing altitudes.

The larger the temperature difference, the more unstable the atmosphere may become. When higher altitudes get cold more quickly than normal, and are also very dry at low levels, it can become more likely that a pyrocumulonimbus event will develop during a large fire.

We used high-resolution climate modelling of projected lower atmospheric instability and dryness conditions to assess the risk of pyrocumulonimbus in southeastern Australia between 2060 and 2079, compared with 1990-2009. We then overlaid this information with the forest fire danger index to identify particularly dangerous fire days.

We were then able to identify how often dangerous fire weather days occurred at the same time as a dry and unstable atmosphere. Verifying our models against past observations, we then examined how often these two characteristics coincided in the future under climate change, should our greenhouse gas emissions remain on their current trajectory.

The results were startling. From 2060 onwards, we saw sharp increases in dangerous fire days across southeast Australia that coincided with atmospheric conditions primed to generate firestorms.

These extremely dangerous days also shifted across seasons, starting to appear in late spring, whereas historically Australian pyrocumulonimbus wildfires have typically been summer phenomena.

Across large areas of Victoria and South Australia, on average, we saw four or five more days every spring that were conducive to pyrocumulonimbus events.




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These were sobering findings, even in a land of extremes like Australia. Our research suggests human-caused climate change has already resulted in more dangerous weather conditions for bushfires in recent decades for many regions of Australia. These trends are very likely to increase due to rising greenhouse gas emissions.The Conversation

Giovanni Di Virgilio, Research associate, UNSW; Andrew Dowdy, Senior Research Scientist, Australian Bureau of Meteorology; Jason Evans, Associate Professor, UNSW; Jason Sharples, Associate Professor, School of Physical, Environmental and Mathematical Sciences, UNSW Australia, UNSW, and Rick McRae, Researcher, Bushfire Cooperative Research Centre, ACT Emergency Services Agency

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate explained: why coastal floods are becoming more frequent as seas rise



As sea levels rise, it becomes easier for ocean waves to spill further onto land.
from http://www.shutterstock.com, CC BY-ND

James Renwick, Victoria University of Wellington


CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

I saw an article claiming that “king tides” will increase in frequency as sea level rises. I am sceptical. What is the physics behind such a claim and how is it related to climate change? My understanding is that a king tide is a purely tidal effect, related to Moon, Sun and Earth axis tilt, and is quite different from a storm surge.

This is a good question, and you are right about the tides themselves. The twice-daily tides are caused by the gravitational forces of the Moon and the Sun, and the rotation of the Earth, none of which is changing.

A “king” tide occurs around the time when the Moon is at its closest to the Earth and Earth is at its closest to the Sun, and the combined gravitational effects are strongest. They are the highest of the high tides we experience.

But the article you refer to was not really talking about king tides. It was discussing coastal inundation events.




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When tides, storms and sea levels combine

During a king tide, houses and roads close to the coast can be flooded. The article referred to the effects of coastal flooding generally, using “king tide” as a shorthand expression. We know that king tides are not increasing in frequency, but we also know that coastal flooding and coastal erosion events are happening more frequently.

As sea levels rise, it becomes easier for ocean waves to penetrate on to the shore. The biggest problem arises when storms combine with a high tide, and ride on top of higher sea levels.

The low air pressure near the centre of a storm pulls up the sea surface below. Then, onshore winds can pile water up against the coast, allowing waves to run further inshore. Add a high or king tide and the waves can come yet further inshore. Add a bit of sea level rise and the waves penetrate even further.

The background sea level rise has been only 20cm around New Zealand’s coasts so far, but even that makes a noticeable difference. An apparently small rise in overall sea level allows waves generated by a storm to come on shore much more easily. Coastal engineers use the rule of thumb that every 10cm of sea level rise increases the frequency of a given coastal flood by a factor of three.

This means that 10cm of sea level rise will turn a one-in-100-year coastal flood into a one-in-33-year event. With another 10cm of sea level rise, it becomes a one-in-11-year event, and so on.

Retreating from the coast

The occurrence rates change so quickly because in most places, beaches are fairly flat. A 10cm rise in sea levels might translate to 30 or 40 metres of inland movement of the high tide line, depending on the slope of the beach. So when the tide is high and the waves are rolling in, the sea can come inland tens of metres further than it used to, unless something like a coastal cliff or a sea wall blocks its way.

The worry is that beaches are likely to remain fairly flat, so anything within 40 metres of the current high tide mark is likely to be eroded away as storms occur and we experience another 10cm of sea level rise. If a road or a house is on an erodible coast (such as a line of sand dunes), it is not the height above sea level that matters but the distance from the high tide mark.

Another 30cm of sea level rise is already “baked in”, guaranteed over the next 40 years, regardless of what happens with greenhouse gas emissions and action on climate change. By the end of the century, at least another 20cm on top of that is virtually certain.




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The 30cm rise multiplies the chances of coastal flooding by a factor of around 27 (3x3x3) and 50cm by the end of the century increases coastal flooding frequency by a factor of around 250. That would make the one-in-100-year coastal flood likely every few months, and roads, properties and all kinds of built infrastructure within 200 metres of the current coastline would be vulnerable to inundation and damage.

These are round numbers, and local changes depend on coastal shape and composition, but they give the sense of how quickly things can change. Already, key roads in Auckland (such as Tamaki Drive) are inundated when storms combine with high tides. Such events are set to become much more common as sea levels continue to rise, to the point where they will become part of the background state of the coastal zone.

To ensure cities such as Auckland (and others around the world) are resilient to such challenges, we’ll need to retreat from the coast where possible (move dwellings and roads inland) and to build coastal defences where that makes sense. The coast is coming inland, and we need to move with it.The Conversation

James Renwick, Professor, Physical Geography (climate science), Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change: why Sweden’s central bank dumped Australian bonds



Sweden’s central bank ways it will no longer invest in assets from governments with large climate footprints, even if the yields were high.
Shutterstock

John Hawkins, University of Canberra

What’s happening?

Suddenly, at the level of central banks, Australia is regarded as an investment risk.

On Wednesday Martin Flodén, the deputy governor of Sweden’s central bank, announced that because Australia and Canada were “not known for good climate work”.

As a result the bank had sold its holdings of bonds issued by the Canadian province of Alberta and by the Australian states of Queensland and Western Australia.


Martin Flodén, deputy governor Sveriges Riksbank Central Bank of Sweden

Central banks normally make the news when they change their “cash rate” and households pay less (or more) on their mortgages.

But central banks such as Australia’s Reserve Bank and the European Central Bank, the People’s Bank of China and the US Federal Reserve have broader responsibilities.

They can see climate change affecting their ability to manage their economies and deliver financial stability.

There’s more to central banks than rates

Reserve Bank deputy governor Guy Debelle. Extreme events not cyclical.
DAVID MOIR/AAP

As an example, the new managing director of the International Monetary Fund Kristalina Georgieva warned last month that the necessary transition away from fossil fuels would lead to significant amounts of “stranded assets”.

Those assets will be coal mines and oil fields that become worthless, endangering the banks that have lent to develop them. More frequent floods, storms and fires will pose risks for insurance companies. Climate change will make these and other shocks more frequent and more severe.

In a speech in March the deputy governor of Australia’s Reserve Bank Guy Debelle said we needed to stop thinking of extreme events as cyclical.

We need to think in terms of trend rather than cycles in the weather. Droughts have generally been regarded (at least economically) as cyclical events that recur every so often. In contrast, climate change is a trend change. The impact of a trend is ongoing, whereas a cycle is temporary.

And he said the changes that will be imposed on us and the changes we will need might be abrupt.

The transition path to a less carbon-intensive world is clearly quite different depending on whether it is managed as a gradual process or is abrupt. The trend changes aren’t likely to be smooth. There is likely to be volatility around the trend, with the potential for damaging outcomes from spikes above the trend.

Australia’s central bank and others are going further then just responding to the impacts of climate change. They are doing their part to moderate it.

No more watching from the sidelines

Peter Zöllner of the Bank for International Settlements launched the Green Bond Fund.
BIS

Over thirty central banks (including Australia’s), and a number of financial supervisory agencies, have created a Network for Greening the Financial System.

Its purpose is to enhance the role of the financial system in mobilising finance to support the transitions that will be needed. The US Federal Reserve has not joined yet but is considering how to participate.

One of its credos is that central banks should lead by example in their own investments.

They hold and manage over A$17 trillion. That makes them enormously large investors and a huge influence on global markets.




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Central banks are waking up to climate change dangers. It’s about time


As part of their traditional focus on the liquidity, safety and returns from assets, they are taking into account climate change in deciding how to invest.

The are increasingly putting their money into “green bonds”, which are securities whose proceeds are used to finance projects that combat climate change or the depletion of biodiversity and natural resources.

Over A$300 billion worth of green bonds were issued in 2018, with the total stock now over A$1 trillion.

Central banks are investing, and setting standards

While large, that is still less than 1% of the stock of conventional securities. It means green bonds are less liquid and have higher buying and selling costs.

It also means smaller central banks lack the skills to deal with them.

These problems have been addressed by the Bank for International Settlements, a bank owned by 60 of the central banks.

In September it launched a green bond fund that will pool investments from 140 (mostly central bank) clients.

Its products will initially be denominated in US dollars but will later also be available in euros. It will be supported by an advisory committee of the world’s top central bankers.




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Business big hitters highlight the huge growth in climate risk management


It is alert to the risk of “greenwashing” and will only buy bonds that comply with the International Capital Market Association’s Green Bond Principles or the Climate Bond Initiative’s Climate Bond Standard.

Launching the fund in Basel, Switzerland, the bank’s head of banking Peter Zöllner said he was

confident that, by aggregating the investment power of central banks, we can influence the behaviour of market participants and have some impact on how green investment standards develop

It’s an important role. Traditionally focused on keeping the financial system safe, our central banks are increasingly turning to using their stewardship of the financial system to keep us, and our environment, safe.The Conversation

John Hawkins, Assistant professor, University of Canberra

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Green cement a step closer to being a game-changer for construction emissions



If the cement industry were a country, it would be the third-largest emitter of CO₂ in the world.
Joe Mabel/Wikimedia, CC BY-SA

Yixia (Sarah) Zhang, Western Sydney University; Khin Soe, Western Sydney University, and Yingying Guo, UNSW

Concrete is the most widely used man-made material, commonly used in buildings, roads, bridges and industrial plants. But producing the Portland cement needed to make concrete accounts for 5-8% of all global greenhouse emissions. There is a more environmentally friendly cement known as MOC (magnesium oxychloride cement), but its poor water resistance has limited its use – until now. We have developed a water-resistant MOC, a “green” cement that could go a long way to cutting the construction industry’s emissions and making it more sustainable.

Producing a tonne of conventional cement in Australia emits about 0.82 tonnes of carbon dioxide (CO₂). Because most of the CO₂ is released as a result of the chemical reaction that produces cement, emissions aren’t easily reduced. In contrast, MOC is a different form of cement that is carbon-neutral.

Global CO₂ emissions from rising cement production over the past century (with 95% confidence interval).
Source: Global CO2 emissions from cement production, Andrew R. (2018), CC BY



Read more:
Buildings produce 25% of Australia’s emissions. What will it take to make them ‘green’ – and who’ll pay?


What exactly is MOC?

MOC is produced by mixing two main ingredients, magnesium oxide (MgO) powder and a concentrated solution of magnesium chloride (MgCl₂). These are byproducts from magnesium mining.

Magnesium oxide (MgO) powder (left) and a solution of magnesium chloride (MgCl₂) are mixed to produce magnesium oxychloride cement (MOC).
Author provided

Many countries, including China and Australia, have plenty of magnesite resources, as well as seawater, from which both MgO and MgCl₂ could be obtained.

Furthermore, MgO can absorb CO₂ from the atmosphere. This makes MOC a truly green, carbon-neutral cement.




Read more:
Greening the concrete jungle: how to make environmentally friendly cement


MOC also has many superior material properties compared to conventional cement.

Compressive strength (capacity to resist compression) is the most important material property for cementitious construction materials such as cement. MOC has a much higher compressive strength than conventional cement and this impressive strength can be achieved very fast. The fast setting of MOC and early strength gain are very advantageous for construction.

Although MOC has plenty of merits, it has until now had poor water resistance. Prolonged contact with water or moisture severely degrades its strength. This critical weakness has restricted its use to indoor applications such as floor tiles, decoration panels, sound and thermal insulation boards.

How was water-resistance developed?

A team of researchers, led by Yixia (Sarah) Zhang, has been working to develop a water-resistant MOC since 2017 (when she was at UNSW Canberra).

Adding industrial byproducts fly ash (above) and silica fume (below) improves the water resistance of MOC.
Author provided

To improve water resistance, the team added industrial byproducts such as fly ash and silica fume to the MOC, as well as chemical additives.

Fly ash is a byproduct from the coal industry – there’s plenty of it in Australia. Adding fly ash significantly improved the water resistance of MOC. Flexural strength (capacity to resist bending) was fully retained after soaking in water for 28 days.

To further retain the compressive strength under water attack, the team added silica fume. Silica fume is a byproduct from producing silicon metal or ferrosilicon alloys. When fly ash and silica fume were combined with MOC paste (15% of each additive), full compressive strength was retained in water for 28 days.

Both the fly ash and silica fume have a similar effect of filling the pore structure in MOC, making the cement denser. The reactions with the MOC matrix form a gel-like phase, which contributes to water repellence. The extremely fine particles, large surface area and high reactive silica (SiO₂) content of silica fume make it an effective binding substance known as a pozzolan. This helps give the concrete high strength and durability.

Scanning electron microscope images of MOC showing the needle-like phases of the binding mechanism.
Author provided



Read more:
We have the blueprint for liveable, low-carbon cities. We just need to use it


Although the MOC developed so far had excellent resistance to water at room temperature, it weakened fast when soaked in warm water. The team worked to overcome this by using inorganic and organic chemical additives. Adding phosphoric acid and soluble phosphates greatly improved warm water resistance.

Examples of building products made using MOC.
Author provided

Over three years, the team has made a breakthrough in developing MOC as a green cement. The strength of concrete is rated using megapascals (MPa). The MOC achieved a compressive strength of 110 MPa and flexural strength of 17 MPa. These values are a few times greater than those of conventional cement.

The MOC can fully retain these strengths after being soaked in water for 28 days at room temperatures. Even in hot water (60˚C), the MOC can retain up to 90% of its compressive and flexural strength after 28 days. The values remain as high as 100 MPa and 15 MPa respectively – still much greater than for conventional cement.

Will MOC replace conventional cement?

So could MOC replace conventional cement some day? It seems very promising. More research is needed to demonstrate the practicability of uses of this green and high-performance cement in, for example, concrete.

When concrete is the main structural component, steel reinforcement has to be used. Corrosion of steel in MOC is a critical issue and a big hurdle to jump. The research team has already started to work on this issue.

If this problem can be solved, MOC can be a game-changer for the construction industry.




Read more:
The problem with reinforced concrete


The Conversation


Yixia (Sarah) Zhang, Associate Professor of Engineering, Western Sydney University; Khin Soe, Research Associate, School of Computing, Engineering and Mathematics, Western Sydney University, and Yingying Guo, PhD Candidate, School of Engineering and Information Technology, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.