Climate-Smart Concrete Studied to Reduce CO2
Swedish multinational power company Vattenfall has recently developed what it’s calling a “climate-smart hydropower concrete” that can reportedly use less cement, reducing its overall carbon dioxide emissions by about a quarter.
The company reports by reducing its cement content in structural concrete, there is a direct reduction in the strain on what otherwise would be inputted to the environment. To achieve this reduction in cement quantity and heat development, Vattenfall is using by-products that react with cement in combination with lessons learned from the company’s major periods of expansion in the 1950s and '60s to develop a modern, climate-smart concrete concept.
In wake of the development, Vattenfall is planning to utilize the climate-smart hydropower concrete to replace parts of an existing dam at its Lilla Edet power station in Göta älv near Gothenburg, Sweden. The company plans to complete the dam replacement project by 2024.
“Various methods have been investigated to reduce the amount of cement in structural concrete, thereby reducing both the burden on the climate and the need for cooling that comes with large concrete structures,” Vattenfall wrote. “Extensive tests have been carried out to ensure that the concrete is suitable for construction works and, above all, meets the requirements for dam safety and durability for over 100 years from now.”
Study, Demonstration and Application
One potential risk that comes into play when casting large concrete structures is temperature increases within the concrete itself, leading to cracks if not mitigated properly. Current methods for managing and reducing internal temperatures involve post-cooling via cooling pipes inside the large concrete structures.
However, by reducing the amount of cement required in creating a concrete structure, Vattenfall found that temperature increases were lower than usual, and mostly eliminated the need for post-cooling treatments. For the study, temperature monitoring and strain during hardening of the concrete was done using fiber optic measurements in collaboration with Chalmers University of Technology.
“The objective was to define a climate-smart concrete concept that is ready to be implemented at the start of the construction works,” said Erik Nordström, Development Engineer at Vattenfall R&D. “This is as long as a maintained or extended service life can be assured for the structures and that it´s a robust concrete concept from a production point of view without any disruption or cost increases in the construction phase.”
In addition, working environments could also benefit in that construction workers would no longer be forced to work within tight, narrow spaces because of cooling pipe installations.
To further test the climate-smart concrete concept, a full-scale demonstration casting was carried out together with the contractor, NCC, and the concrete supplier, Thomas Concrete Group. During the demonstration, crews carried out a pump test of the concrete over a longer distance and concrete workers were given the opportunity to try working with the concrete to evaluate whether the properties worked from a practical point of view.
According to Vattenfall, the demonstration casting went excellently without pump stops and the concrete workers were very pleased.
Due to the success of the study and demonstrations, the company is planning to use the concrete concept in other application areas, such as wind power, although some adjustments would have to be reviewed for the composition of the concrete.
“You could use this concept when, for example, casting wind power foundations, although the actual composition of the concrete would then probably need to be slightly adjusted to suit the specific exposure environment,” concluded Nordström.
Reducing Carbon Footprint
Like many other companies and countries, even, climate change initiatives are both surfacing and being redefined as the world aims to tackle its carbon footprint. At Vattenfall, the company is looking to enable fossil free living within one generation.
Not alone in their efforts, in New York, legislature recently passed a bill that is designed to promote the use of low-carbon concrete for state construction projects. Bill S542A requires the Office of General Services to establish guidelines concerning the procurement of low-carbon concrete for state projects. Contractors would need to follow these guidelines and certify that their materials meet guideline targets.
The bill also outlines that the office will need to examine when crafting said guidelines such as incentives—as a tax credit that was initially associated with the bill was removed in the final version that passed. (New Jersey, meanwhile, is looking at similar legislation that still includes a tax incentive.)
The office would then be awarding future contracts to companies based on these climate performances as well as price.
The state maintains that the bill is a crucial step toward its net-zero emissions economy goal by 2050, which was passed in 2019.
In June, Australian clean technology company Mineral Carbonation International (MCi) announced its own intentions to capture industrial carbon emissions to transform into useful materials. The company currently looking to commercialize its technology with other industrial customers and funders. MCi is headquartered in Canberra, Australia, whiles its research and technical facilities are located at the Newcastle Institute for Energy Research where it operates its pilot plant facility.
According to Hamblin Wang, the company is looking for anything that can have carbonates so that new products can be made using its synthetic carbonates. Specifically, the MCi is looking to produce construction materials in larger volumes, particularly for things such as new types of cement and drywall products to replace carbon-emitting Portland cement and gypsum-based materials.
The carbonization and transformation of these types of industrial-based waste would work by submitting the materials to a chemical process MCi has developed that mimic natural weathering—also known as mineral carbonization—to remove carbon from factory emissions and sequester it in solid minerals.
As the CO2 is dissolved into rainwater, a weak carbonic acid is formed which slowly weathers into rock, having had its carbon combine with elements released from the rock by the weathering process to form new carbonate materials.
While in nature, this process can take thousands or even millions of years, MCi has compressed the process into just hours. However, instead of a rock result, MCi uses industrial waste, such as steel slag, mine tailings and bottom ash from incinerators, among others. To form the raw materials, CO2 is bubbled through the waste, approximating the way water-borne carbon interacts with rock in the natural weathering process.
The exothermic process results are a new mineral, which can vary from magnesium carbonate, calcium carbonate, silica, and more.
Although the entire process is aiming to utilize renewable energy, the company reports that crushing the industrial waste is the most energy intensive. In the future, MCi plans to switch entirely to renewables if they are to offer a viable contribution to global decarbonization efforts.
And most recently, earlier this month, Norway launched work on what it’s calling “Project Longship”—a 1.7-billion-euro ($2.01 billion) project that plans to bury up to 1.25 billion tons of captured carbon dioxide under the North Sea.
The initiative calls for the injection of CO2 captured from factory emissions in depleted oil and gas fields.
In a white paper on the project, the Norwegian government reported that in December 2020, there was no sufficient incentives in the current market to implement, nor develop CCS. “This is in part due to high investment costs, low-income potential in the short term and high risk,” the document read. “In addition, the price of emitting greenhouse gases is lower than the cost of CCS, and the development of technology may have the characteristics of a public good.”
For the project, developer and operator of CO2 transport and storage Northern Lights will capture the CO2, which will then be shipped in liquid form to the North Sea and pumped into the bedrock up to three kilometers (almost 2 miles) below the seabed.
Another industrial partner involved with the CCS project, Heidelberg Cement, plans to convert its cement factory into a carbon-neutral plant, where it will capture all of its carbon emissions and covert them into liquid for underground storage.
In addition to converting CO2 into liquid for storage, the project also intends to store carbon captured directly from the atmosphere. Earlier this year, Northern Lights signed a letter of intent with Swiss direct air capture company Climeworks, that has developed machines to suck carbon from the atmosphere and could one day provide CO2 for storage as part of the project.
Phase one of the project is expected to be completed by 2024 and plans to have a capacity of 1.5 million tons per year. The project aims to kickstart the CCS market by developing technologies and lowering the cost of capturing and storing atmospheric CO2.