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Carbon capture from cement manufacturing nears market readiness

A consortium led by Australian firm Calix is now well on the way to completing a pilot plant for its breakthrough technology that will capture carbon emissions from the manufacture of lime cement. Other projects with similar aims to reduce the global warming impact of construction with concrete are also racing to the marketplace.

The pilot plant, known as LEILAC (Low Emissions Intensity Lime And Cement), is based in Europe to take advantage of European funding for carbon capture and storage projects. But the core technology was developed by Australian firm Calix, which won Australia’s Company of the Year and the Food & Agritech awards in 2015.

With global urbanisation adding a city the size of Shanghai to the planet every four months, and much of this involving cement, it’s crucial to tackle the 60 per cent of total CO2 emissions that are released directly, and unavoidably, from processing of limestone. The cement and lime industries contribute seven per cent (or 1.9 Gt annually) of total global anthropogenic CO2 emissions.

Europe was responsible for one fifth of this total in 2013, and to meet the European Union’s emission reduction target alone, carbon capture will need to be applied to 59 per cent of European cement plants. But globally all cement and lime industries are under intense competitive and cost pressures, so the race is on to find a cost-effective way to address the climate challenge of concrete.

So far, as we detailed in December 2016, the best available technologies for the production of cement and lime presently have no carbon capture capability, and reducing climate emissions in the cement and lime industries is mostly confined to improving kiln efficiencies and using non-fossil fuels.

Calix has been operating a 25 kilo-tonne per year kiln since 2013 that embodies indirect heated and direct CO2 separation for magnesite (MgCO3). The LEILAC project will extend and scale up the technology into lime and cement. Calix partnered with European organisations to overcome what it saw as the limitations of Australia’s geographical isolation.

The pilot plant, financed by the EC’s Horizon 2020 fund, is at the HeidelbergCement plant in Lixhe, Belgium, and aims to capture 95 per cent of carbon dioxide emissions and is currently on budget and schedule to be completed and verified by the end of 2020.

How the plant will work

Emphasis has shifted from carbon capture and storage (CCS) in the power sector to carbon capture and utilisation (CCU) in industry; specifically by transforming carbon dioxide into fuels, chemicals and materials. This is attracting more investment attention because carbon capture and storage in hubs and industrial clusters is considered a better business model.

The European Commission is currently supporting five carbon capture and storage projects, of which three are in the cement industry, and two carbon capture and utilisation projects, which involve using carbon dioxide to produce methanol or ethanol. LEILAC is receiving €11.9 million as a contribution to the total project cost of €20.8 million.

One of the cement industry projects, CEMCAP, recently released a film providing information about its innovative oxyfuel cooler technology. It is aiming to use captured carbon dioxide cool the clinker, which is produced from the kilns as a stage to producing the final cement

The third project, CLEANKER (CLEAN clinKER), is testing carbon capture by calcium looping at industrial scale. Here, CO2 is separated from the furnace exhaust gas by the carbonation of calcium oxide, and an oxyfuel-operated calciner, in which a pure stream of carbon dioxide is generated. The hope is that all but 10 per cent of the total carbon dioxide will be captured.

A demonstration plant is being connected to an existing kiln line of the Buzzi Unicem plant in Vernasca, Italy.

Adding this technology to an existing cement production plant will mean an increase in the cost of the final product, but the CLEANKER project anticipates this would only be €25 per tonne of cement.

The LEILAC project anticipates negligible extra cost. The downstream processing costs of liquefying, transport and safe storage are not part of LEILAC. This is because these steps are not cement or lime specific and are being developed in cross-sectorial approaches for all CO2-emitting industries and utilities in Europe.

When integrated into new plants, or retrofitted into existing plants that are fired with biomass or waste, the total CO2 emissions would be reduced by more than 85 per cent compared to conventional fossil fuel fired lime and cement plants, without significant operating issues, energy or capital penalty.

When the LEILAC project is completed in 2021, a cement and lime industry CCS roadmap will be developed.

CarbonCure is another CCU technology being pioneered in the US, which involves injecting CO2 into the final cement so that it is absorbed. This makes it harder and even stronger than the conventional cement so that less cement is required in the production of concrete.

Under tests, it has been proven to reduce the initial setting time by 40 per cent and increase the one and three day compressive strengths by 14 per cent and 10 per cent respectively.

While it is true that concrete absorbs carbon dioxide from the atmosphere as part of the normal weathering process, if CO2 is introduced in the manufacturing stage instead (under controlled conditions), more of the gas is absorbed by the cement at an earlier stage and better quality concrete is produced.

A skyscraper is currently being built in Atlanta city that incorporates 48,000 cubic metres of concrete made with the CarbonCure technology, which it is claimed diverted 680 metric tonnes of CO2 from being released into the atmosphere. CarbonCure hopes that its technology will be adopted around the world.

The European Bank for Reconstruction and Development is also supporting carbon emissions reduction in the cement industry as part of its Innovative Green Finance program. Its financing has extended as far as Egypt’s cement industry where, in partnership with relevant ministries and the national cement industry association, it has produced a technology upgrade roadmap that will reduce annual emissions of carbon dioxide by 47,000 tonnes.

Using a €15 million loan from the bank, the Egyptian government has pledged to increase by 15 per cent the use of alternative fuels and to reduce clinker content to less than 80 per cent in the industry by 2030.

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