Two of the most common and critical components in the construction industry are also two of the biggest emitters of carbon, steel and cement.
The big challenge over the next decade or more is how to wrestle those emissions to net zero without causing the price of building anything larger than an outhouse to soar beyond reach.
For construction it’s a tangled web. While construction ranks tenth out of 10 sectors for emissions that stat doesn’t account for its use of metals, cement and other materials which rank higher on the list, posing a quandary for architects and developers in creating lower carbon structures.
But can we design robust structures using less materials like steel and concrete without incurring liability and shortening building lifecycles? And can we engineer new technologies to reduce energy consumption while simultaneously reducing emissions and containing costs?
Steel makers are shifting their approach with pilots using hydrogen, electricity or natural gas to replace the traditional metallurgical coal used in smelters to make new steel. While recycled steel can be made in electric arc furnaces, it is raw steel which represents the biggest emissions.
Similarly, cement manufacturers globally are also committing globally to reducing their emissions and getting to net zero on a region-by-region basis because each region has its own set of challenges.
The issue is going to be cost: “Carbon tax alone adds $2 or $3 per m3 to the cost of concrete and we’re pumping hundreds of thousands of cubic metres a year,” says Paul de Berardis, director of building science and innovation at industry group Residential Construction Council of Ontario.
Adam Auer, CEO and former vice-president of environment and sustainability at the Cement Association of Canada, says cement producers are looking at a road map response in getting to net zero, starting at the clinker phase, through cement production and binders, to concrete construction iself and carbon storage.
Members of the Global Cement Association are exploring different avenues to the same goal, he says, and ultimately will share best practices onces they’ve evaluated all the options individual, spreading both the risk and costs.
Some progress has already been made with emissions in cement production down 20 per cent over the last three decades with a goal of a further 25 per cent by 2030 cutting 5 billion tonnes of CO2 from emissions.
He says making cement with less clinker combined with technologies such as the Canadian-based Carbon Cure which injects CO2 in to concrete to aid and strength curing, using more byproducts such as steel slag and other construction waste, seeking out other energy sources such as hydrogen and reducing transportation emissions and energy consumption generally are all on the table.
”We need to move to a construction cultural shift,” he says. “How can we use the material more efficiently?”
Part of that is designing structures with less steel and concrete, he says, with thinner pours, ultimately using less material and reducing the carbon footprint.
When cement is poured is also a big question with cold weather pours requiring more energy to cure properly.
“Finally, we need to consider that concrete absorbs carbon as it cures from the air,” he says. “Some 20 to 22 per cent of the carbon emitted is reabsorbed over the lifetime of the concrete.”
Even carbon negative is possible when the soup to nuts picture is considered, he says, pending the application of new techniques, technologies and fuels.
The key to controlling prices, however, will be incentives to avoid carbon pricing and at the same time support from the federal government and others to support development of the technologies and facilities needs to shift production.
The Canadian Steel Producers Association is also pledging to be net zero but says it will need government support such as the $400 million from the federal government and $500 million donated by the Ontario government to build a new blast furnace to make new steel at ArcelorMittal Dofasco’s (AMD) Hamilton steel plant. The plan is to use Direct Reduced Iron (DRI) feedstock to cut three million tones of CO2 emissions by 2028 when it is operational.
The $1.7 billion upgrade will remove 60 per cent of emissions from the plant replacing metallurgical coke with natural gas. Eventually, AMD will convert to another fuel such as hydrogen or electricity when it is feasible and globally there are pilot projects underway investigating those options.
However, the near future reductions in Hamilton are mostly from switching to natural gas which ironically many activists still see as a fossil fuel. Some of the reduced emissions will also come from not needing to transport coke to the plant.
AMD is already offering certified “green steel” projecting demand of 600,000 tonnes this year in Europe.
Demand generally is forecast to rise with steel coming off a high in 2021 to hit US$750 a tonne in early 2022. However, ResearchAndMarkets.com says the global long steel market will almost double by 2030. Long steel is made billets and blooms and the products are consumed mostly by the construction sector and made with electric are furnace. However, as the demand for such green steel rises so too with the prices of scrap steel which goes into making recycled steel.