Engineering toolboxes to verify the fate mechanism and permanence of drawndown carbon

点击翻译按钮获取中文摘要

Anthropogenic carbon dioxide emissions are the largest contributor to the Earth's climate change emergency. Environmental assessments show that to mitigate irreversible climate change and to meet the UNFCC Paris Agreement, a more than 95% reduction in the global carbon emissions from the 2018 level is required. Emissions reduction is insufficient to achieve this, hence negative emissions technologies, which result in what is now known as `carbon drawdown', must be widely adopted to reduce atmospheric CO2 levels directly. With such approaches being actively developed and field tested, there is urgent need to develop better engineering toolboxes for determining the fate mechanism and permanence of sequestered and stored carbon. There are two forms of soil carbon sequestration that can play a role in climate change mitigation: inorganic and organic carbon. Scientific evidence has shown that not only the widely researched meta-stable soil organic matter can trap atmospheric CO2, but also the geologically stable pedogenic carbonates. Now, it is crucial to tackle another important knowledge gap, which is on how soil organic carbon (SOC) can be readily classified into more stable and less stable fractions, and how this is related to the long-term storage and transport of carbon in soils and subsoils. The goal of this research program is to develop novel experimental (characterization) and numerical (reactive transport) toolboxes to accurately estimate SOC sequestration rates, amounts, stability, and speciation. Concepts from Engineering, Earth Sciences, Agriculture, and Economics will be leveraged to develop tools for monitoring, quantifying, and predicting carbon sequestration in soils. In the short term, advances in photoelectrocatalytic sensors and advanced high-pressure thermogravimetric analysis techniques will be leveraged to make use of photocatalysis, gasification, pyrolysis and thermal oxidation for the purpose of quantitatively classifying SOC fractions that include labile (less stable), humus, and resistant (more stable). Thermodynamic, kinetic and sorption data will be collected and generated to enable conventional geochemical modeling of soil carbon transport to be able to account for a family of SOC compounds of different stabilities that age or degrade under variable soil, crop and climate conditions. For the long term, this research aims: (i) to have direct policy implications, particularly as it pertains to verifiable and certifiable carbon credits for long-lasting (10 to 100 years, or ideally more) carbon removal; and (ii) to equip carbon sequestration verifiers with superior methods to determine the permanence of all forms of newly sequestered carbon in soils.