Preliminary study for a Direct Air Capture (DAC) pilot plant: Technology screening, site requirements, cost development

On behalf of E.ON Research & Technology, FfE, together with its partners RWTH FCN and TUM CTV, investigated the possibilities for a Direct Air Capture (DAC) pilot plant in Germany. The advantages and disadvantages of various technologies were first analyzed in interviews with various DAC start-ups. The knowledge gained was then incorporated into analyses of possible heat supplies, costs and conceivable locations. These showed that

• the requirements for suitable DAC locations are highly dependent on the respective DAC technology,
• industrial waste heat is a cost-effective heat source for DAC technologies with thermal regeneration processes, and
• electrochemical processes are currently expected to have the lowest costs for CO₂ removal.

Motivation

The IPCC report shows that negative emissions through CO₂ removal from the atmosphere (CDR, Carbon Dioxide Removal) are essential in order to achieve climate neutrality by 2050 due to unavoidable or very difficult to avoid residual emissions and probable “overshoot” scenarios [1]. In addition to natural CO₂ removal methods, which are e.g. based on biomass use, afforestation or changes in land use, some of these are also to be generated technically, e.g. through direct air capture (DAC). Due to the more flexible choice of location and independence from biomass availability, DAC also has advantages over the other methods despite its currently higher costs.

Goal

The various technologies and costs of DAC should be considered comprehensively to enable well-founded business model decisions. This includes, among other things, an evaluation of location factors and various heat sources for DAC systems. The final goal is a resulting cost analysis and microeconomic evaluation.

Project structure

Four working packages (WP) were completed as part of the project (see Figure 1). WP1 represents the market analysis including interviews with various start-ups and a tool for location analysis from the stakeholder perspective. In WP2, individual locations were evaluated microeconomically using various options for heat supply (industrial waste heat, solar thermal energy and hydrothermal energy). The different DAC process routes were compared in parallel in WP3 with regard to their techno-economic parameters. Finally, the synthesis in WP4 shows three possible paths for the development of a DAC portfolio.

FfE-Tasks within the project

In addition to project coordination, the FfE worked on the following focal points.

As part of WP1, the FfE was responsible for the interviews with the DAC startups (WP1.1) and developed a tool to assess the suitability of German districts as DAC locations (WP1.3). The following location analysis (WP1.4) rounds off the work package. The processing of WP4 was carried out together with the FCN of RWTH Aachen University. Possible use cases were selected and evaluated.

Methodology

The interviews were conducted with DAC startups that pursue different technological approaches. The market research and selection were carried out together with the TUM CTV with a focus on German and European companies. The interviews were based on an interview guideline that takes into account technological and entrepreneurial aspects in equal measure.

In order to select possible suitable locations for a DAC pilot plant, a data-based tool for location analysis at district level was developed. Based on the interviews, company-specific relevant energy-economic, ecological and socio-economic factors were derived and quantitatively stored. The individual factors can be weighted variably. Based on the results of the site analysis, possible suitable locations for DAC systems of the various technologies could then be identified at district level, as shown in Figure 2 as an example.

The selection of possible use cases was made by synthesizing the results of WP1 to 3 together with the project partners and E.ON.

Results

At the beginning of the project, the topic of heat (availability) was given great importance. However, the DAC market analysis showed that electro-chemical processes with little or no heat input are now also in advanced development and have lower specific energy requirements.

The market analysis has also shown that DAC can only be competitive with other technical negative emission technologies if energy prices are low. Regions with high potential for renewable energies are best suited for this. Taking into account the comparatively high energy prices, possible paths were nevertheless identified as to how negative emissions from DAC could be generated in Germany and what opportunities there are for an economic business case:

• Path 1: Flexible electricity procurement from renewable energies through dynamic electricity tariffs for electro-chemical processes for DAC.
• Path 2: Use of low-cost heat sources, such as industrial waste heat in thermal processes for DAC

The site analysis has shown that regions near the North Sea are the most promising for electrochemical processes in Germany due to their high RE potential and proximity to possible offshore CCS capacities. The district of Duisburg has the highest potential for heat-based DAC technologies that require a temperature level of up to 100°C and want to use industrial waste heat.

Project Partners

• EON Research & Technology
• TUM Professorship Chemical Process Engineering
• RWTH Institute for Future Energy Consumer Needs and Behavior

Literature

[1] Cross-sectoral Perspectives – Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change – IPCC, 2022.