5. Net Positive Ocean Impact

Running Tide selects materials with the goal of improving ocean health. In addition to terrestrial biomass, our carbon buoys may contain carbonates and/or macroalgae, both of which reduce ocean acidification by interacting with fast cycle carbon that is present as dissolved carbon dioxide in the upper levels of the ocean. We avoid deleterious impacts on the ocean by ensuring that all materials used are natural and commonly occurring in the ocean, including non-proliferating variants of purpose-grown macroalgae, minerals such as carbonates that are distributed throughout the world’s oceans, and terrestrial biomass that already enters the ocean in vast quantities through rivers and other natural pathways.

Environmental screening and evaluation

All materials utilized by Running Tide are subject to environmental testing in a laboratory setting prior to being introduced into the ocean, to ensure that pollutants or toxins are not inadvertently introduced to the marine environment. This process, which may be conducted by Running Tide or an external partner lab, includes elemental analysis, contamination testing, and material reactivity testing. Individual materials follow a staged progression process throughout lab testing, with defined “exit criteria” at each phase of evaluation to ensure that all materials meet our core ecological and system design requirements prior to undergoing or coastal field trials.

For both terrestrial biomass and macroalgae, this testing includes a biological evaluation against basic biological rubrics (such as if the species is invasive to the region or not), an assessment of the biogeography (i.e., the natural geographic distribution) of the species in question, nutrient analysis (such as evaluating the C:N:P, or Carbon-Nitrogen-Phosphorus ratio, of the organic material), conducting biocide analyses for terrestrial biomass, and reactor testing across a range of variables to ensure viability. For macroalgae, sorus tissue is collected locally via divers in the areas where we operate and brought into the laboratory setting for testing prior to propagation. When collecting this initial sorus tissue, we are mindful to maintain local biodiversity by not depleting local species populations.

Alkaline material evaluation

When sourcing alkaline materials, Running Tide considers both primary mined products such as calcium carbonate, as well as residual byproducts such as alkaline brines from desalination and lime kiln dust . When prioritizing which alkaline materials to target for carbon removal, we take a number of factors into account, including the carbon intensity and ecological impact of production, the presence of any harmful major, minor, or trace elements, shipping distances from production site to port, packaging and shipping options, as well as any material handling considerations.

Currently, lab testing conducted on all alkaline materials we consider includes a toxic metal concentration analysis and similar reactor testing, which measures material dissolution rate, alkalinity generation, and trace metal release. Running Tide is developing a comprehensive suite of environmental impact indicators against which we can rate these alkaline materials, to avoid sourcing materials that could negatively impact the climate, as well as the health of freshwater and marine resources.

How we measure net positive ocean impact

• Material-specific testing and quantification of biological and chemical conditions.

• Material-specific assessment and review of species biogeography and location eligibility.

• Material-specific elemental, toxicity, and biocide analyses.

• External laboratory testing and comparison of results against acceptable concentration guidelines.

• Material reactivity testing in laboratory settings against ocean conditions.

• In certain cases, coastal or open ocean research is conducted to answer critical research questions and evaluate materials in the real-world environment, often in collaboration with leading .

• Over time, we expect our measurement capabilities and understanding of key environmental indicators related to our material inputs to continue to mature.