Carbon removal efficiency and energy requirement of engineered carbon removal technologies
This week, we take a deeper dive into the paper recently published in RSC (Royal Society of Chemistry) Sustainability. The study was conducted by Daniel L. Sanchez from the University of California-Berkeley, in the US.
To ensure we can achieve net negative emissions, it is important to carefully account for both lifecycle emissions and energy requirements of the processes aimed to remove carbon dioxide from the atmosphere. In this paper, the authors perform a harmonized lifecycle greenhouse gas assessment for twelve engineered carbon dioxide removal (CDR) technologies - such as direct air capture (DAC), bioenergy with carbon capture and storage (BECCS), and ocean fertilization. In this assessment, both total energy required and carbon removal efficiency, which reflects the fraction of carbon that is removed from the atmosphere from that which is captured over the process lifecycle (net flux of carbon) are considered. As a result, this allows for a consistent comparison across diverse technologies both in terms of their carbon capture potential and the energy they require for operation.
The authors discuss how different CDR technologies show wide variability in how effectively they can remove CO2 from the atmosphere and the criticality of such technologies’ energy intensity as their energy requirements are substantial. Indeed, the energy intensity of methods like DAC is one of the most significant barriers to scaling them up without increasing emissions elsewhere. The paper discusses the balance between efficiency and energy needs, highlighting that the economic feasibility of large-scale deployment will hinge on reducing energy costs, improving technology efficiency, and finding low-carbon energy sources for operations. Techno-Economic Trade-Offs are also highlighted, together with the need for a systems-level understanding of how these technologies could integrate into national and global carbon budgets: while engineered solutions can complement natural processes, their role should be framed within a broader policy strategy that considers both environmental and economic factors.
The authors develop a framework with consistent system boundaries, emissions factors and transportation distances across approaches, as shown in Figure 1, relying – when possible – on data associated with delivered carbon removal credits. Figure 2 shows a snapshot of the results: all examined methods are placed according to their carbon efficiency and their energy use in their most likely embodiment. DAC processes require much more energy than other technologies, due to the very low concentration of CO2 in the atmosphere causing high energy requirements for capture and storage. Interestingly, due to their low energy use, many of the most energy and carbon efficient approaches are “passive” biomass-based or open systems such as ERW or biomass sinking in the ocean.
Here is a list of the main take-aways from this paper:
- Carbon removal efficiency and energy use vary significantly across engineered carbon dioxide removal (CDR) technologies, and this influences their viability at scale.
- Energy requirements are a major challenge, with technologies like direct air capture (DAC) being energy-intensive, limiting their scalability without low-carbon energy sources.
- Cost-effectiveness and scalability hinge on reducing energy costs and improving the efficiency of these technologies.
- Policy should support energy-efficient CDR innovations and invest in research, pilot projects, and demonstration-scale operations to address uncertainties.
- CDR technologies must be integrated into a broader climate strategy, balancing their potential with environmental, economic, and equity considerations.
Read the full paper here: Carbon removal efficiency and energy requirement of engineered carbon removal technologies