UK Breakthrough Could Slash Emissions From Cement
The title of this post. is the same as that of this article on the BBC.
This is the sub-heading.
Scientists say they’ve found a way to recycle cement from demolished concrete buildings.
These five paragraphs outline, why cement is such an environmental problem.
Cement is the modern world’s most common construction material, but it is also a huge source of planet-warming gas emissions.
That is because of the chemical reactions when you heat limestone to high temperatures by burning fossil fuels.
Recycling cement would massively reduce its carbon footprint. Researchers say that if they switched to electric-powered furnaces, and used renewable energy like wind and solar rather than fossil fuels, that could mean no greenhouse gases would be released at all.
And that would be a big deal. Cement forms the foundation of the modern economy, both literally and metaphorically.
It is what binds the sand and aggregate in concrete together, and concrete is the most widely used material on the planet after water.
If cement was a country, it would be the third biggest source of emissions after China and the US, responsible for 7.5% of human-made CO2.
This article shows how by applying chemical magic to two effectively unrelated processes; the recycling of steel and the recycling of concrete to make new cement, very high rewards are possible.
Cambridge University are calling their new product electric cement.
As large amounts of electricity are used in an arc furnace, to produce the two products
These paragraphs outline the innovative Cambridge process.
Cement is made by heating limestone to up 1600 Celsius in giant kilns powered by fossil fuels.
Those emissions are just the start. The heat is used to drive carbon dioxide from the limestone, leaving a residue of cement.
Add both these sources of pollution together and it is estimated that about a tonne of carbon dioxide is produced for every tonne of cement.
The team of scientists,, has found a neat way to sidestep those emissions.
It exploits the fact that you can reactivate used cement by exposing it to high temperatures again.
The chemistry is well-established, and it has been done at scale in cement kilns.
The breakthrough is to prove it can be done by piggybacking on the heat generated by another heavy industry – steel recycling.
When you recycle steel, you add chemicals that float on the surface of the molten metal to prevent it reacting with the air and creating impurities. This is known as slag.
The Cambridge team spotted the composition of used cement is almost exactly the same as the slag used in electric arc furnaces.
They have been trialling the process at a small-scale electric arc furnace at the Materials Processing Institute in Middlesbrough.
These are my thoughts.
The Only Inputs Are Steel Scrap, Green Electricity And Used Cement
Consider.
- We probably need to increase the percentage of steel scrap we collect.
- Gigawatts of green electricity in a few years, will be available in those places like Port of Ardersier, Port Talbot, Scunthorpe and Teesside, where large amounts of steel will be needed.
- I can envisage large steel users having their own hybrid electric cement/electric arc furnace plants.
- Used cement would be collected and brought to the plants.
- Years ago, I used to live next door to an old World War II airfield. The farmer who owned the airfield, told me, that the concrete was his pension, as when he needed money, he called a company, who crushed it up for aggregate.
I can see a whole new integrated industry being created.
Conclusion
This could be one of the best inventions since sliced bread.
The Anonymous Widower 