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Tackling the climate challenge – part two

World Cement,

Learning from the power sector: Carbon capture and Oxyfuel

CCS and most of the CCU-technologies require CO2 to be concentrated to a high level, or at least to a level that CO2 can be reasonably liquefied. Therefore the primary objective of the cement industry is to develop either a process integrated technology or end-of-pipe solution to increase the CO2 concentration from roughly 25% for a conventional kiln to at least 75%, preferably higher than 90% purity.

In 2014, HeidelbergCement started the first industrial flue-gas carbon capture project in the industry at the Norcem cement plant in Brevik, Norway, in close cooperation with ECRA. 75% of the €12 million project is funded by the Norwegian government through the Climit program of Gassnova. The intermediate results of these tests were so positive that a feasibility study for a full-scale application has been launched.

As Carbon Capture is capital intensive and requires significant operational costs, ECRA has analysed to what extent the operation of a kiln in ‘oxyfuel’-mode would reduce these costs. The principle of an oxyfuel kiln is that calcination of limestone takes place in a pure oxygen atmosphere and the exhaust gas is recirculated to the clinker cooler. In order to have enough oxygen in the main burner, pure oxygen is added to the cooler as well. By such an operation, the CO2 content after the preheater can be increased to more than 70%. In the so-called CEMCAP program, funded by the Horizon 2020 program of the EU, several critical components will be tested for an oxyfuel operation mode. HeidelbergCement is facilitating the construction and testing of a demo clinker cooler under simulated oxyfuel conditions at its Hannover works.

Calix: a process CO2 separation technology for the cement industry

While Carbon Capture and Oxyfuel are developments originating from the power sector and are converted for use in a cement kiln, HeidelbergCement is exploring other innovations that are cement-kiln specific. The technology provider Calix commercially operates an indirectly heated calciner for the production of magnesium oxide in Australia. The calcination of limestone however requires a 150°C higher temperature than magnesium. The advantage of such an indirectly heated calciner is that the CO2 released during calcination is not mixed with the exhaust gases, but can be separated directly resulting in greater than 95% pure CO2 without an additional energy-penalty. As no advantage comes for free, in this case the challenge is to operate a double walled calciner with the inner pipe being resistant to 1050°C.

To solve this challenge a consortium has been created around Calix, including HeidelbergCement, Lhoist, Cemex, Amec Foster Wheeler and expert R&D institutes. The EU has awarded the proposal with a €12 million fund to develop the technology and to test it at industrial scale at HeidelbergCement’s Lixhe plant in Belgium.

Utilising carbon: technologies and applications under review

As mentioned before, in addition to CCS, the development of CCU-applications is key. HeidelbergCement is monitoring this domain, which consists of many start-up companies and developing technologies. All of them are at different stages of maturity and with a wide variety of potential applicability and hurdles to overcome. Meanwhile the company has defined a set of KPI’s against which all these initiatives are being measured.

HeidelbergCement’s strategy is to implement quick-wins, even when they are small in terms of CO2 abatement, and to systematically develop the larger scale potentials in the long-term in combination with the appropriate technology developers and downstream partners.

CO2 for algae cultivation

At the Degerhamn cement plant in Sweden as well as at the Canakkale works in Turkey, HeidelbergCement runs R&D-programs to enhance micro-algae cultivation by exposing the strains to CO2 rich flue gas.

The project in Canakkale is set-up under the umbrella of Tübitak, the leading Turkish institute for industrial R&D projects. After intensive strain selection, practical tests have been done connected to a slipstream of the flue gas, in open ponds and in panel- and tubular photo-bioreactors. The micro-algae have shown an accelerated growth rate due to the CO2 and were not affected by the regular impurities of the flue gas. The generated micro-algae have been positively tested by external certification body for its nutrition use in fish hatcheries in Turkey.

At the project in Sweden, named Algoland, the Linneaus University has brought in its expertise in micro-algae production. Various cultures have been tested and it appeared that mono-cultures were not as resistant as mixed cultures especially those naturally available in the Baltic Sea. Tests have been performed both in summer as well as winter conditions. Growth rates have been remarkably good and similar to those at the project in Canakkale. In addition, no problems with flue gas minor components were noticed.

The next step at both sites is to prepare for larger production volumes and to evaluate the path to commercial application.

This is part two of a three-part article written for World Cement’s May issue and abridged for the website. Subscribers can read the full May issue by signing in, and can also catch up on-the-go via our new app for Apple and Android. Non-subscribers can access a preview of the April 2016 issue here.

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