Life Cycle Assessment of Coastal Enhanced Weathering for Carbon Dioxide Removal from Air

Spyros Foteinis, James S. Campbell, Phil Renforth

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
48 Downloads (Pure)

Abstract

Coastal enhanced weathering (CEW) is a carbon dioxide removal (CDR) approach whereby crushed silicate minerals are spread in coastal zones to be naturally weathered by waves and tidal currents, releasing alkalinity and removing atmospheric carbon dioxide (CO2). Olivine has been proposed as a candidate mineral due to its abundance and high CO2 uptake potential. A life cycle assessment (LCA) of silt-sized (10 μm) olivine revealed that CEW’s life-cycle carbon emissions and total environmental footprint, i.e., carbon and environmental penalty, amount to around 51 kg CO2eq and 3.2 Ecopoint (Pt) units per tonne of captured atmospheric CO2, respectively, and these will be recaptured within a few months. Smaller particle sizes dissolve and uptake atmospheric CO2 even faster; however, their high carbon and environmental footprints (e.g., 223 kg CO2eq and 10.6 Pt tCO2–1, respectively, for 1 μm olivine), engineering challenges in comminution and transportation, and possible environmental stresses (e.g., airborne and/or silt pollution) might restrict their applicability. Alternatively, larger particle sizes exhibit lower footprints (e.g., 14.2 kg CO2eq tCO2–1 and 1.6 Pt tCO2–1, respectively, for 1000 μm olivine) and could be incorporated in coastal zone management schemes, thus possibly crediting CEW with avoided emissions. However, they dissolve much slower, requiring 5 and 37 years before the 1000 μm olivine becomes carbon and environmental net negative, respectively. The differences between the carbon and environmental penalties highlight the need for using multi-issue life cycle impact assessment methods rather than focusing on carbon balances alone. When CEW’s full environmental profile was considered, it was identified that fossil fuel-dependent electricity for olivine comminution is the main environmental hotspot, followed by nickel releases, which may have a large impact on marine ecotoxicity. Results were also sensitive to transportation means and distance. Renewable energy and low-nickel olivine can minimize CEW’s carbon and environmental profile.

Original languageEnglish
Pages (from-to)6169–6178
Number of pages10
JournalEnvironmental Science and Technology
Volume57
Issue number15
Early online date3 Apr 2023
DOIs
Publication statusPublished - 18 Apr 2023

Keywords

  • environmental chemistry
  • general chemistry
  • enhanced rock weathering
  • negative emissions technology
  • ocean alkalinity enhancement
  • enhanced silicate weathering in coastal systems
  • ocean alkalization

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry

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