From pilot project to the first commercial CO₂ storage site in…

The HEIM Group and neustark have been collaborating for the past three years in Germany to drive decarbonization in the construction industry via permanent carbon removal (CDR). What started with a pilot project to mineralize CO₂ into recycled concrete to build a real estate development in Berlin, has led to operating the first commercial CO₂ storage facility in Germany. Today, we are removing tons and tons of CO₂ from the air together.

Neustark, in collaboration with the HEIM Group, deployed the first large-scale CO₂ storage facility in Germany in autumn 2023.
Customers and partners from construction, politics, and media have reacted positively to the HEIM Group’s new business field and the jointly achieved climate impact.
With the new product of mineralized recycled aggregate (mRC-GK), HEIM can offer added value to its customers seeking construction material with a lower carbon footprint already today.

HEIM Group unites various business fields in construction, building material extraction, recycling, energy, and agriculture under one roof. The company operates sites across Germany, including a recycling site in Berlin. This is where neustark retrofitted its first storage plant in September 2023, and where the site has been storing hundreds of tons of CO₂ since its launch. And where Heim has since been producing a greener construction material: carbonated recycled aggregate.

That recycled materials can be processed into high-quality secondary building materials, which are not inferior to primary building materials, has been a pillar of managing director Philipp Heim’s strategy for some time already. The subsidiary RC-Baustoffe GmbH & Co. KG (formerly Heim Deponie und Recycling GmbH) processes demolition materials such as bricks and concrete supplied from demolition sites in the Berlin region. Up to 200,000 tons of this waste is recycled into high-quality building materials per year. Now, this recycled material has an even greener footprint: it’s not only recycled, but also enriched with atmospheric CO₂.

The neustark CO₂ storage facility at the HEIM site in Berlin.

New standards in durable carbon removal

HEIM Group are the first in Germany to apply the neustark’s mineralization process to store CO₂ in demolition waste such as concrete, slurry and slag. The construction materials continuously seek ways of optimizing value chains by linking existing and new business fields. Or in Oliver Dürr’s, HEIM’s Head of Controlling and driving force behind the cooperation, words:

“As a medium-sized company, this pioneering work enables us to shine light on how to decarbonize our industry, as well as help us to attract potential buyers and keep pace with socio-political developments.”

Neustark and HEIM are working to further expand their collaboration:

"Working closely together helps us to optimize the existing plant. In the future, we may expand the value chain or build additional sites. Having a partner we can trust in is crucial when it comes to breaking new ground.”

The HEIM and neustark teams at the launch of the CO₂ storage site in Berlin.

CO₂ storage debut in Germany

The site was launched in autumn 2023 at an event with 120 people attending: Alongside representatives from politics, business, academia, and the media, we set important political impulses, made new contacts and increased the boosted for CO₂ storage in Germany. First-hand experience of new technologies help to pave the way for widespread trust in and modified norms for greener construction materials – including carbonated RC products.

Our process starts with demolition concrete, slurry or slag, and leads to an innovative solution: CO₂-enriched granules. The granulate can be resold as frost protection, base layer material or recycled aggregate, to be used in road construction or to produce recycled concrete. This resource-efficient building material can replace conventional, making a commercially and environmentally sustainable contribution for the building material recycler, the producer, and ultimately the end customer.

This is how the process looks like:

Processing steps of carbonated demolition concrete (source: HEIM Group).

CO₂ storage as a new business model

Oliver Dürr reveals that customers and partners have responded positively to their new business field. The new product, mineralized recycled aggregate (mRC-GK), offers customers added value: On the one hand, the use of demolition concrete as an aggregate for concrete leads to sustainable recycling, and on the other hand, according to the Swiss research institute Empa, mineralization has a positive effect on the physical and technical properties of the product:

Recycled concrete made with mRC-GK has higher compressive strength
Mineralization results in increased bulk density
Mineralization leads to reduced water absorption

With the introduction of this new technology and product, HEIM was able to position themselves in a new field, but also revitalize existing business relationships. The company is already involved in various development projects using sustainable raw materials. Several projects are currently in the planning stage, one of which is due to start construction soon. Around 2,500 tons of mRC-GK have already been delivered for this project.

“Many of our customers are following the trend and increasingly sourcing mineralized products to integrate within their existing or new, sustainable product portfolios, of course always adhering to existing standards.”

Long-term partnership with industry pioneers

It all started with “CORE”, a pilot project initiated by the German Senate Department for Mobility, Transport, Climate Protection, and Environment (SenMVKU) with the aim of developing sustainable building materials.

“The HEIM Group and neustark share the same vision. That’s why we decided to take these first steps and the many more to come together.” – Philipp Heim, Managing Director and owner of the HEIM Group

Specifically, the pilot project’s objective was to develop CO₂-reduced concrete (CORE) based on mineralized aggregate. The result: the consortium was able to certify the innovative building material and put it into practice as a first in Germany. The RC concrete was used in a large-scale residential development project called Friedenauer Höhe in Berlin. The benefits?

1) According to the study by the Institute for Energy and Environmental Research (ifeu), CORE can reduce emissions by up to 20%.
2) The use of CORE also conserves natural resources.
3) Recycled concrete is both environmentally friendly and has a high technical performance.

The real estate development project “Friedenauer Höhe” in Berlin (source: Instone Real Estate).

Figures and facts on the HEIM x neustark CO₂ storage site in Berlin.

Paradigm shift in the build environment: Why more construction material recyclers and concrete producers should rely on CO₂ reduced concrete

Demolition concrete is neustark’s carbon sink. You have the demolition concrete, slurry and slag – we have the carbon capture and storage technology. Together, we can create a new business field and drive the decarbonization of the construction industry.

By working with neustark, you can create a new revenue stream by storing CO₂. An investment that pays for itself within 3-5 years. Large-scale CO₂ storage facilities, such as the one operated by HEIM Group in Berlin, can store 1,000 or more tons of CO₂ per year. The CO₂ is permanently removed from the atmosphere, generating important negative emissions. This enables you to enter a new market and contribute to sustainability efforts at the same time.

Unlike other methods of CO₂ utilization or removal, neustark’s solution is already operational today. By collaborating with us, you have an immediate impact on your business, while simultaneously strengthening your company’s innovative future.

FAQs

In addition to the storage of CO₂, the mineralization process simultaneously neutralizes the slurry. This means that excess residual water can be fed into the wastewater without high disposal costs.
Carbon dioxide mineralization is a process in which CO₂ reacts with alkaline metal to form solid carbonate minerals.

Demolished concrete aggregate contains hydrated cement phases. These hydrated cement phases are in contact with water, e.g. pore water – and thus in a solid-liquid equilibrium. Part of the hydrated cement is dissolved in the water and therefore present as ions. As CO₂ is also dissolved in this water, new mineral that exhibit lower solubility than the hydrated cement phases precipitate. And voilà, calcium carbonate (CACO₃) is formed.

Thus, the CO₂ and the hydrated cement undergo a chemical transformation to form rock. This so-called carbonation reaction of 1 kg CO₂ releases heat such that the temperature of 1,000 kg of concrete increases by about 2.5°C.

CACO₃ is considered to be amongst the most permanent ways to sequester carbon. Only temperatures above 600°C or very strong acids could trigger the release of CO₂. This ensures that the CO₂ remains stored in the concrete, even if it is demolished again after being reused.
Currently we can store around 10 kg of CO₂ per ton of demolition concrete on an industrial and economical basis – and we’re continuously working on optimizing this figure. Depending on the material characteristics, we can store up to 25 kg of CO₂ per ton.

In terms of speed, our latest plant stores around 1000 kg of CO₂ per hour in concrete granulate. As a comparison: fast-growing pine trees absorb about 20kg of CO₂ per year . So one neustark plant can do in one hour what 50 trees need a whole year for.

Or, in other words, within 24 hours, one neustark plant can store the same amount of CO₂ in demolished concrete granulate as the CO₂ that is on average emitted by two single-family homes heating with oil in Switzerland in a year’s time.

For more information, please see Johannes Tiefenthaler et al’s Technological Demonstration and Life Cycle Assessment of a Negative Emission Value Chain in the Swiss Concrete Sector.