Assessment of CO₂ Emissions from Crushed Stone Transport for Site Selection of Enhanced Weathering Systems

In order to achieve carbon neutrality by 2050, negative emission technologies are required, and enhanced weathering is attracting attention. In this process, rocks are crushed and spread on farmland to fix CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. However, since CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> is emitted during the process from rock mining to spreading, it is necessary to clarify the CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> reduction effect over the entire life cycle. In this study, a case study focusing on transportation distance and spreading area in Hokkaido, Japan has been conducted to evaluate CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> emission reductions. The area of farmland and the transportation distance from the quarry to the farmland were calculated using Geographic Information System (GIS). The relationship between transportation distance and farmland area was analyzed to clarify the characteristics of each quarry. From the result of the case study, CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> emissions from transportation account for up to 30% of total emissions. Furthermore, the quarry case also shows a reduction in CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> emissions.