Tuesday, June 25, 2019

Cement produces more CO2 than trucks

From Bloomberg:

The most astonishing thing about cement is how much air pollution it produces.

Manufacturing the stone-like building material is responsible for 7% of global carbon dioxide emissions, more than what comes from all the trucks in the world. And with that in mind, it’s surprising that leading cement makers from LafargeHolcim Ltd. in Switzerland to Votorantim Cimentos SA in Brazil are finding customers slow to embrace a greener alternative.

Their story highlights the difficulties of taking greenhouse gases out of buildings, roads and bridges. After wresting deep cuts from the energy industry, policymakers looking to extend the fight against global warming are increasingly focusing on construction materials and practices as a place to make further reductions. The companies are working on solutions, but buyers are reluctant to pay more.

While architects and developers concentrate on the energy used by their buildings, it’s actually the materials supporting the structure that embody the biggest share of its lifetime carbon footprint. Cement’s contribution to emissions is especially immense because of the chemical process required to make it.

About two-thirds of the polluting gases that come from cement production stem from burning limestone. Kilns are heated to more than 1,400 degrees Celsius (2,600 Fahrenheit), about four times hotter than a home oven set to the self-clean cycle. Inside the kiln, carbon trapped in the limestone combines with oxygen and is released as CO2, the most abundant greenhouse gas.

A ton of cement yields at least half a ton of CO2, according to the European Cement Association. That’s more than the average car would produce on a drive from New York to Miami. And a single mixer truck can carry about 13 tons. Hundreds or even thousands of tons go into ordinary office buildings.

What comes out of the kiln is called clinker, the key raw ingredient of cement. It’s the substance that, when mixed with gypsum and water, binds with gravel to harden and form concrete. Many companies are working to cut the amount of clinker in their cement, which requires new and sometimes untested recipes.

Others are looking at substitutes. Those include fly-ash, which comes from the chimneys of plants that burn coal, or slag from steel-making blast furnaces. They trigger a chemical reaction and form what’s known as a geopolymer binder.

Geopolymer cement has performance advantages and a huge sustainability edge over traditional mixes, according to Cameron Coleman, chief executive officer of Wagners Holding Co., which is based in Toowoomba near Brisbane in Australia.

“This alternative eco-friendly binder technology reduces the carbon emissions associated with normal Portland cement by 80% to 90%, and also has a much lower embodied energy,” Coleman said by email. “We have been working with leading companies in South East Asia, New Zealand, India, Europe and the Middle East who are extremely interested in adopting this technology.”

That strategy won’t work for long in Europe and the U.S., where fly-ash is the main clinker substitute and coal plants are closing. There, the focus is on efficiency and using fossil-fuel alternatives for heat. The European Cement Association says its producers already get 44% of their energy from cleaner sources and wants to raise that proportion to 60% by 2050. Instead of using coal, it’s creating heat with used tires, mineral oil and industrial waste.

[Read more here]

I am very confident that the world will replace fossil fuels in electricity generation within 20 or 25 years, and will convert most land transport to EVs over the same time frame.  This will happen because people are getting frightened by global heating and the climate emergency, and because the costs of these new technologies are plunging. Why not do something about global heating when you'll actually cut costs by doing it?

But that will leave agriculture, iron and steel and cement, which by 2040 or 45 could make up 80% of emissions.  There are alternatives in cement production as this article discusses.  There are others: I talked about green concrete here.  Iron and steel could be produced using methane or hydrogen to reduce iron ore to pure iron.  Unlike electricity from renewables or EVs, these will not be cheaper than their high-carbon equivalents.

Clearly, to encourage the update of low-carbon cement and steel, we need a price on carbon.  In Europe, there is one, currently €24 (US$ 27) per tonne of CO₂.  It's only a question of time before Europe starts applying that price to the carbon content of imports from countries which do not have a carbon price.  The surge of Greens in the recent European elections makes that inevitable.  All the conventional parties are starting to feel how the breath of environmentalism is starting to become a breeze and then a gale.  What's more, the current extreme heatwave in Europe, as bad as or worse than last summer's,  will only harden attitudes.  With a carbon price, cement and steel will start to produce low-carbon products.  And the only remaining sector to de-carbonise will be agriculture.  But it will happen there too.  Because it has to.

No comments:

Post a Comment