On the way to realizing the potential of long-term safe carbon dioxide removal out of the atmosphere by artificial photosynthesis

Efficient methods to remove carbon dioxide from the atmosphere are key to stabilize Earth's global mean temperature. Artificial photosynthesis (AP) was recently proposed as a land-based method for carbon dioxide removal (CDR), aiming at an energy and land-use efficient production of safe and long-term stable sink products such as carbon flakes or oxalate [1,2]. Solar-driven electrochemical CO2 reduction is widely investigated in the context of carbon capture and utilization such as the production of solar fuels. However, the application for CDR, requiring dedicated sink products, has been explored only scarcely although AP was estimated to yield a more than tenfold higher potential solar-to-carbon efficiency [1]. Here, we report on the progress towards realizing the potential of this negative emission technology chain, starting with energy harvest, via carbon dioxide reduction, conversion [2], and to storage. We draw on advances in photo-electrochemistry, ab-initio simulations of molecular dynamics, Earth System Model simulations [4], geological storage assessment and sustainability assessment to clarify that firstly there are no fundamental scientific hindrances of the approach. Secondly, we evaluate where challenges and future research perspectives for the approach lie, and discuss the prerequisites for realizing its potential for scale-up by the year 2050.

 

[1] May, M. M. & Rehfeld, K. ESD Ideas: Photoelectrochemical carbon removal as negative emission technology. Earth System Dynamics 10, 1–7 (2019). doi:10.5194/esd-10-1-2019

[2] May, M. M. & Rehfeld, K. Negative Emissions as the New Frontier of Photoelectrochemical CO₂ Reduction. Advanced Energy Materials 2103801 (2022) doi:10.1002/aenm.202103801.

[3] D. Lörch, A. Mohammed, H. Euchner, J. Timm, J. Hiller, P. Bogdanoff, M. M. May, From CO₂ to solid carbon: reaction mechanism, active species, and conditioning the Ce-alloyed GaInSn catalyst, Journal of Physical Chemistry C, 128, 49, 2024, doi:10.1021/acs.jpcc.4c05482.

[4] Adam, M., Kleinen, T., May, M. & Rehfeld, K. Land conversions not climate effects are the dominant indirect consequence of sun-driven CO2 capture, conversion, and sequestration. Environ. Res. Lett. (2025) doi:10.1088/1748-9326/ada971.