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Novacem Carbon-negative Cement

Challenge

Develop a radical technology to reduce the carbon intensity of cement.

Problem

Cement is a US$170bn industry supplying 2.9 billion tonnes of cement to support global economic development every year. Supply is expected to grow at 3-5% per annum, particularly driven by development needs in India and China.

However, the cement production process accounts for up to 5% of man-made emissions of CO₂, making the industry one of the largest industrial emitters. Production of one tonne of ordinary Portland cement, the most widely used type of cement, emits an average of 800kg of CO₂. Of the total emissions created in the cement production process, 50% derive from the raw material used (calcium carbonate), 45% from the fossil fuels needed to drive the main chemical reaction and the remaining 5% are from transport.

The cement industry acknowledges a need to embrace lower carbon solutions; see the recent Cement Sustainability Initiative Technology Roadmap which incorporated views from the world’s largest cement companies. However, currently proposed solutions will either not deliver the scale of the change needed (eg, partial replacement of ordinary Portland cement with waste products) or are unproven and uneconomic (eg, carbon capture and storage).

Solution

Novacem has developed a new class of cement which offers performance and cost parity with ordinary Portland cement, but with a carbon-negative footprint. The cement is based on magnesium oxide (MgO) and hydrated magnesium carbonates. The production process uses accelerated carbonation of magnesium silicates under elevated levels of temperature and pressure (ie 180 ˚C/150 bar). The carbonates produced are heated at low temperatures (700˚C) to produce MgO, with the CO₂ generated being recycled back in the process. The use of magnesium silicates eliminates the CO₂ emissions from raw materials processing. In addition, the low temperatures required allow use of fuels with low energy content or carbon intensity (ie biomass), thus further reducing carbon emissions. Additionally, production of the carbonates absorbs CO₂; they are produced by carbonating part of the manufactured MgO using atmospheric/industrial CO₂. Overall, the production process to make one tonne of Novacem cement absorbs up to 100kg more CO₂ than it emits, making it a carbon negative product.

This production process is based on 20 years of research on the mineral carbonation of magnesium silicates. These minerals are widely dispersed with accessible worldwide reserves estimated to significantly exceed 10,000 billion tonnes.

In 2012 Novacem technology was bought by Calix.

Benefits

Carbon negative product
Carbon dioxide consumed in the production process
Large end-use market

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