external page publication<\/a>.\u00a0<\/p>\nExploiting synergies <\/p>\n
For the study, the researchers collaborated with the US company Heirloom Carbon Technologies. The company is one of the world\u2019s leading developers of DAC based on calcium looping \u2013 a process that utilises a chemical cycle involving various calcium compounds. Calcium carbonate is the starting point, i.e. limestone, which is quarried worldwide. DAC plants using calcium looping and cement works operate with the same calcium compounds and employ the same process: limestone is heated until it decomposes into quicklime and CO\u2082 \u2013 a process known as calcination.<\/p>\n
In integrated cement production using calcium looping DAC, a kiln powered by electricity rather than fossil fuels, such as coal or gas, is harnessed for calcination. This avoids greenhouse gas emissions from the combustion kiln. At the same time, the CO\u2082 produced during the calcination process can be captured directly, as it is not contaminated by combustion exhaust gases. According to the study’s calculations, electrifying the kiln and using direct CO\u2082 capture alone could reduce the climate impact of cement production by 78 per cent by 2050.<\/p>\n
Once water has been added to quicklime, the slaked lime absorbs further CO\u2082 from the atmosphere and is converted back into limestone, which can then be reused as a raw material for cement production. The more often the calcium undergoes this cycle of contact with the air before being processed into cement, the more CO\u2082 the plant removes from the atmosphere. The CO\u2082 captured from the atmosphere is not bound in the cement. Instead, it is compressed and transported to underground storage sites.<\/p>\n
Real-world figures <\/p>\n
\u201cHeirloom was an ideal partner for us because the company is already operating the first calcium looping DAC systems on a commercial scale,\u201d as Bolongaro underlined. In California, the company has been operating a plant since 2023 with an annual nominal capacity of 1000 tonnes CO2.<\/p>\n
Another, significantly larger plant is due to be built in Louisiana in the upcoming years. \u201cThe collaboration was beneficial for both sides: our partner wanted to learn more about the technology\u2019s environmental footprint \u2013 and we were able to base our calculations and scenarios on primary industrial data from real-world operations,\u201d explains Bolongaro.<\/p>\n
The current study is the first prospective life-cycle analysis for DAC using calcium looping on an industrial scale. In conducting the analysis, the researchers not only considered the operation of the plant, but also all environmental impacts along the process chain; from raw material extraction through the construction and operation of the plant to the storage of the captured CO\u2082.<\/p>\n
Initially, Bolongaro and her team wanted to find out whether larger, commercial plants remove more CO\u2082 over their entire life cycle than they produce. In a second step, the researchers examined whether the reduction in CO\u2082 emissions comes at the expense of other environmental factors, such as water or land use.<\/p>\n
Their findings showed that by far the largest share of the environmental footprint is attributable to the energy required for the process, as the capture of CO\u2082 from the air is very energy-intensive. This also applies to other DAC processes. As part of the study, various energy scenarios were therefore tested: operating the plant using the current US electricity mix, drawing on a heavily decarbonised electricity mix comprising wind and solar energy, and employing a fully autonomous system with photovoltaics and battery storage.<\/p>\n
\u201cWe were able to show that the technology has a net-negative carbon footprint; in other words, commercial calcium looping DAC plants with CO\u2082 storage remove more CO\u2082 than they generate over their entire lifecycle,\u201d says Bolongaro. \u201cDepending on the energy mix used in our projections, the efficiency of CO2 removal by 2050 ranges between 85 and 96 per cent.\u201d In other words: for every tonne of CO2 that is captured and stored, 40 to 150 kg of CO2 are generated in the process chain. This is comparable to figures from other DAC systems. Powering the plant by renewable energy achieves the highest efficiency.<\/p>\n
What the field trial still has to show <\/p>\n
\u201cThe major advantage of DAC plants using calcium looping is that this technology can be integrated into a well-established cement production process,\u201d explains Bolongaro. The adjustments required to integrate DAC into cement production are relatively straightforward.<\/p>\n
First and foremost, additional air contactors are needed to capture CO\u2082 from the atmosphere. Furthermore, the kiln in which limestone is calcined at high temperatures must be powered by low-carbon or carbon-free energy to ensure the highest possible net removal.<\/p>\n
\u201cFrom a climate perspective, this approach is very promising as a scalable solution that integrates into existing industrial supply chains, while simultaneously driving the decarbonisation of the cement sector forward,\u201d as Bolognaro underlines. A more detailed investigation of the physical and economic limits of this integration is now required.<\/p>\n
The key calculations for the study are based on future scenarios up to the year 2050 and assume significant progress in the decarbonisation of the electricity supply. Furthermore, some of the plant components, in particular indirectly heated electric calcining kilns, are not yet in large-scale industrial use. It therefore remains to be seen whether the system can be operated economically; a detailed cost analysis was not part of the study to date.<\/p>\n
Consequently, for Bolongaro, the results represent an important starting point that highlights the climate potential of the approach.\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Cement is one of the most in-demand building materials of our time. Every year, around four billion tonnes…\n","protected":false},"author":2,"featured_media":118620,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[6],"tags":[57758,5977,1202,51],"class_list":["post-118619","post","type-post","status-publish","format-standard","has-post-thumbnail","category-zurich","tag-bardow","tag-d-mavt","tag-news","tag-zurich"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ch\/117134296795762062","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/118619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/comments?post=118619"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/118619\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media\/118620"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media?parent=118619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/categories?post=118619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/tags?post=118619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}