Using CO2 to make construction products and materials

Dr Anthea Blackburn, Senior Scientist – Catalyst Development, Econic.

The publication of the Committee on Climate Change (CCC)’s latest report, calling for a shift to an ambitious, yet much-needed, net zero carbon emissions target in the UK has highlighted a growing awareness of the need to act now to slow down climate change.

Following the calls for the UK to reduce carbon emissions to net zero by 2050, a range of businesses and industries will need to assess their current impact on the planet. With mounting public pressure, as evidenced by the Extinction Rebellion protests in April 2019, companies are taking action to ensure that their operations are greener. Unilever, for instance, has reduced its carbon emissions by 39% per tonne of product manufactured since 2008, whilst L’Oreal and Pepsi are working towards using 100% reusable, recyclable or compostable packaging by 2025.

The 2050 target for net zero is a formidable challenge, but far from an impossible goal, and the built environment sector will play a key role in helping the UK to achieve this. Over recent years, we have seen an increasing trend towards green building design and construction techniques, including the use of lower volatile organic compound building materials, offsite framing and the use of passive solar building design.

Whilst these efforts are a positive step forward, much more will need to be done if we are to reach net zero carbon within the next three decades. The steps taken so far to become greener are commendable, but the property and construction sectors still have a considerable impact upon the planet – it’s estimated that as much as 40% of carbon emissions come from buildings (most of which is from the manufacture of construction products and materials) and 50% of the world’s raw material consumption is in the development and use of building stock.

Time is of the essence if we are to limit the planet’s temperature rise to just 1.5°C, and it’s vital to address all elements of our building stock’s carbon lifecycle before 2050. The UK Government is implementing legislation to help guide the architecture and construction sectors towards becoming greener, not least through the recent announcement of a ban on the use of solid fuel heaters in new-build properties. However, further efforts need to be made in order to make the dramatic changes necessary. However, what if the solution to this problem was, quite literally, all around us? Indeed, the answer to calls to reach net zero carbon emissions could lie in the widely maligned molecule itself: CO2. In fact, CO2 could be used to make a variety of products and materials, including those used in building design and construction. After all, atmospheric CO2 is readily available and, thanks to developments in catalytic science, could be captured and used to create polyurethane in a process that replaces up to 50% of the oil-based raw materials.

From the rigid foam insulations that reduce heat loss, to the coatings used to protect flooring and the exteriors of buildings, polyurethane products are commonplace in building construction and design. If polyurethane made with waste CO2 was to be widely adopted by the architectural and construction sectors, net carbon emissions could be vastly reduced – potentially by up to four million cars’ worth each year. Not only does the production of polyurethane utilising CO2 as a raw material help to reduce net carbon emissions, through reduction in the use of, and therefore production of, traditional oil-based alternatives as a feedstock, further CO2 emissions are also prevented.

When considering how to make building design greener, many Architectural Technology professionals may look to consider using bio-alternatives, whether these be natural materials such as cork and mineral wools, or bio-based polyols made using plant oils. However, the production of these materials places a vast strain on agricultural resources, and they are often costly for manufacturers to import. What’s more, polyurethane materials made using captured waste CO2 typically perform better than these biodegradable alternatives – rigid polyurethane foams, for example, require less than half the amount of cork or mineral wool to provide the same degree of insulation, and also have been found to have improved flame retardancy properties. Other benefits to these products include good rigidity; increased abrasion resistance; and improved chemical resistance, meaning that they are able to withstand the test of time.

Making use of captured CO2 in building development is not limited to the production of polyurethane, however: concrete, one of the biggest contributors to the construction sector’s emissions, can also be manufactured using waste CO2. Once such example is Carbicrete, whose technology enables the production of cement-free, carbon-negative concrete, reducing greenhouse gas emissions by replacing cement in the mix with a steel slag (a by-product of the steel industry, cured with CO2 to make it carbon-negative) and capturing CO2 in the curing process. Carbicrete’s finished product is not only greener, but is also more durable and cost-effective than cement-based concrete.

Carbon capture and utilisation technology’s green applications have also been realised by Mineral Carbonation International, who convert CO2 into stable, solid carbonate materials, which are then used to produce a range of building materials, including high performance concrete, plasterboards and electrical insulation. Further developments in this field are also coming down the track, including spray polyurethane foams, which will offer similar benefits of improved insulation and fire resistance to rigid foams made using CO2.

Now more than ever, climate change is an issue that requires drastic attention. From the school strikes and Extinction Rebellion protests, to the publication of the CCC report, the UK’s Government, businesses and public must make changes to lessen the impact we have on our planet. Reaching the target of net zero carbon emissions may seem a long way off, but if all industries take the appropriate measures to lower their carbon footprints, progress can be made. For the architectural and property sectors, making use of captured CO2 as a raw material could be one way to not only reduce emissions in building design and construction, but also realise the product benefits offered by CO2. With a goal of 2050 to reach, the sector will need to act now and adopt these innovative techniques, in order to help the UK reach net zero carbon.

This article originally appeared as ‘Designing for change: using CO2 to make architecture greener’ in Architectural Technology Journal (at) issue 132 published by CIAT in winter 2019. It was written by Dr Anthea Blackburn, Senior Scientist – Catalyst Development, Econic Technologies.

--CIAT

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