Modelling ocean alkanization

Models are crucial for integrating field and experimental observations, simulating alkalinity release rates over long time scales, and assessing the regional and global ocean alkalinization potential.  

Coastal Carbon uses modeling for three purposes. First, we use sediment models to elucidate how processes that produce and consume alkalinity are connected. Second, we use maps of environmental conditions at the seafloor to determine the spatial variability of current CO₂ uptake and possible future CO₂ sequestration potential. Third, based on our experimental results, we develop alkalinization reaction network simulators that can be connected to existing ocean models and allow assessment of regional and global potential and feasibility of ocean alkalinization under different application scenarios.  

Field studies and incubation experiments give us valuable knowledge about the processes that generate alkalinity on a local scale and under controlled environmental conditions.

It is, however, impossible to simulate every environment or visit every field site in the world. We use numerical models to upscale and valorize the knowledge gained in field studies and experimental incubations. Furthermore, the larger impact of enhanced alkalinity release on, for example, economy or the coastal ocean can only be assessed using numerical approximations of the real world. Coastal Carbon uses different types of models, ranging from life cycle analyses (LCA) for investigation of the economic and environmental feasibility of mineral additions to biogeochemical models of the coastal seafloor to assess the alkalinity generation efficiency of mineral additions. Using tailored model approaches, Coastal Carbon bridges the gap from idealized lab experiments to real life ocean alkalinization. 

In theory, coastal ocean alkalinization works. The real-world application potential however depends crucially on two questions: 

1. How expensive is it to do coastal ocean alkalinization?In a worst-case scenario, active mineral addition to coastal environments is too economically expensive to ever be utilized in real life.
2. How much CO₂ is produced during coastal ocean alkalinization? The CO₂ drawdown resulting from alkalinization needs to exceed the CO₂ produced throughout the ocean alkalinization process. 

These questions are answered utilizing a life cycle analysis. This is a model framework that follows the entire lifecycle of coastal ocean alkalinization from mineral acquisition to applying minerals by ship into the coastal zone. For each step we calculate what the monetary cost is, and how much CO₂ is produced. By adding up these numbers, we can investigate what determines the economic cost and CO₂ emissions during coastal ocean alkalinization.​

The CO₂ drawdown potential at any particular location depends on a number of environmental and mineral parameters. We can calculate the CO₂ drawdown potential by combining maps that show the spatial distribution of these parameters. The resulting CO₂ drawdown map allows us to determine hotspots for coastal ocean alkalinization.