The construction sector accounts for a quarter of carbon dioxide emissions, in Sweden and globally. Researchers at Chalmers University of Technology and Gothenburg University studied in detail the construction of an eight km stretch of road and calculated how many emissions can be reduced now and through 2045, looking at everything , from the choice of materials to production technology, including supply chains and transport. .

“We have identified several fruits at hand, and if we tackle these first, it will become easier and cheaper to reduce emissions further in the future,” says Ida Karlsson, PhD student at Chalmers and participant in the Mistra Carbon Exit project.

Researchers assessed the possibilities of reducing emissions on an eight-kilometer stretch of Swedish Autobahn 44 between Lidköping and Källby, which was completed in 2019. This was one of the Swedish Agency’s first projects. transport in which a full climate calculation has been carried out. All materials and activities involved in its construction have been calculated for their total climate impact – energy and materials used in construction and the emissions to which they contribute.

“We used contractor Skanska’s climate calculation as an input to break down emissions by material and activity, and then we analyzed how much they could be reduced. What materials are used? How are they produced? What alternatives are available and how could these alternatives develop until 2045? ”Explains Ida Karlsson.

The climate calculation showed that the contractor was able to reduce emissions by 20% compared to the Swedish Transport Agency’s benchmarks. But the researchers also showed that emissions could be cut in half with technology already available today – and completely eliminated by 2045.

Ida Karlsson’s research is part of the Mistra Carbon Exit project, which focuses on so-called transformative solutions. These require both time and significant investment and include, for example, the production of carbon dioxide-free steel, cement, concrete and asphalt, as well as fossil-free or electric vehicles. . Solutions are developed and implemented, but climate-friendly technologies and choices already exist today. Ida Karlsson would like to highlight four:

    – Transport optimization

    – Recycling and reuse of excavation masses, asphalt and steel

    – Material efficiency and design optimization

    – Replacement of cement clinker as a binder in concrete

“If you optimized the transport of materials, excavation masses and waste, for example, significant gains could be made. We could be better at transport logistics in Sweden. In addition to the transport of materials and waste to and from a road construction site, a lot of movement also takes place within projects, ”she explains.

Biomass, an important issue

Biomass plays an important role in the short and long term. Many industries need biomass to reduce their emissions. It can be used, for example, as a fuel in the production of asphalt, cement and steel, for the production of electricity or as a fuel for vehicles. Already today, Sweden imports 95 percent of the raw materials needed for transport biofuel, because it is cheaper than using domestic materials. This is hardly a sustainable solution as more and more countries import biomass. Ida believes that we need a coherent national strategy for the production and use of biomass.

“Where there are fossil-free alternatives, like electrification, they should be used. But then the policy must clearly point towards such a development. Otherwise, the biomass will simply go to whoever pays the most and not where it pays it. would make the best use of it. “

Other areas for improvement

Another area for improvement could be asphalt recycling, says Ida Karlsson.

“The relevant legislation has recently changed, but new, more efficient working methods are not yet fully implemented. There are also different technologies to choose from depending on the quality of the tarmac, the weight of vehicles traveling the road, etc. Recycling requires energy but can still significantly reduce emissions, as asphalt is largely made of bitumen, a variant of crude oil.

Concrete is another major source of emissions. In Sweden cement clinker is used as a binder in infrastructure concrete, but in other countries materials such as slag from steel production or fly ash from coal-fired power plants are used as a substitute. partial cement clinker, significantly reducing emissions.

“Here we must dare to recognize the long positive experiences of its use in other countries, such as Norway, and adopt these techniques and measures even if they have not been used before in Sweden.”

It’s time to take a clear path forward

Ida Karlsson calls for clear plans, first until 2030, then until 2045 as well.

“If you already know what you want in 2030, you can make requests today. And then businesses can also know that, ‘OK, if we are to be able to meet these requirements by 2030, then we have the opportunity to invest in the technology to achieve this goal. “Because large investments will be required to change the production and transportation operations. Then you have to make sure that there are requirements, needs, incentives and most importantly that there is climate neutral electricity available. “

“Transformation solutions – electrification, carbon capture, carbon-free steel and concrete – require significant time and investment. But if we’ve already reaped the rewards at hand, the rising costs of processing solutions don’t have to be that great. This is why the fruits on hand are so important to start with, because they can reduce emissions even more in the future, at a lower cost. “

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