Enhanced Rock Weathering (ERW)

News: Tech giants, airlines and fast fashion firms lining up to buy carbon credits from ERW projects to “offset” or cancel out their own emissions.

About Enhanced Rock Weathering (ERW)

• It is an innovative, nature-based carbon dioxide removal (CDR) technology designed to combat climate change by accelerating the earth’s natural rock weathering process.
• ERW speeds the process up by using quick-weathering rocks like basalt that are ground finely to increase their surface area.
• Aim: It aims to turbocharge a natural geological process called weathering.
  • Weathering is the breakdown of rocks by carbonic acid, which forms when carbon dioxide in the air or soil dissolves into water.
  • Weathering occurs naturally when rain falls on rocks, and the process can lock away carbon dioxide from the air or soil as bicarbonate, and eventually limestone.

Effectiveness of ERW

• Debatable: ERW is still a fairly new technology and there are questions about how much carbon it can remove.
• Difficult to measure: Rates depend on variables including rock type and size, how wet and hot the climate is, soil type and land management.
• Miscalculation: The most popular technique measures “cations“, positively charged ions that are released from the rock during weathering.
  • If there are stronger acids than carbonic, then it will react with those, so measurable cations are produced even when carbon dioxide is not captured.

Benefits

• The added rock increases soil alkalinity, which can boost crop growth, soil nutrients and soil formation.
• Basalt is both naturally abundant and often available as a byproduct of quarrying, lowering the costs of the process.