The team at Planetary is grateful for the engaged participation of the Nova Scotia community regarding our work. We recognise that there are many perspectives at play in the community and aim to target our responses to the “curious and concerned citizen”. We also recognise that some groups of people (e.g., activists, scientists, etc.) may be interested in a more detailed answer or wish to explore a different facet of the topic, and we invite you to continue to reach out to us with additional questions.

 For questions not specific to our Nova Scotia project, please see our general FAQs about Planetary’s process.

  • Are there risks related to September’s field trial? How are you mitigating them?


    The current study has been designed in conjunction with Dalhousie University to maximise the amount of knowledge that we are able to gain while minimising all risks.

    The study began with a literature review to identify any risks and challenges that might be known based on other studies. We then conducted a series of in-the-lab experiments to answer fundamental questions such as:

    • Exactly how much carbon dioxide is taken up by seawater given various concentrations of various alkalinity types?
    • How quickly does this carbon uptake happen?
    • At what amount of alkalinity addition does the process become less efficient?

    Answering these questions with our academic partners at Dalhousie University and the University of Miami contributed significantly to our XPRIZE Milestone award in April 2022. These ‘beaker-scale’ experiments are critical and continue to be an important part of our work today. 

    To better simulate real ocean alkalinity addition, and to test out measurement capability using real ocean sensors, we conducted experiments in the Dalhousie Aquatron – Canada’s largest university aquatic research facility. Along with these experiments, our partners at Dalhousie University also conducted experiments on phytoplankton to understand the safe local limits on the part of the ecosystem most likely to be affected. The collaboration between the Planetary and Dalhousie research teams has produced the necessary foundational data to advance this project to the next stage – a small-scale field trial. This trial will help us gain a better understanding of the potential of this climate and ocean restoration solution in the Halifax area. 

    Whenever considering risks, we need to compare the risk of action to the risk of inaction. Namely, what will happen if we don’t move forward with this project? Climate change continues to intensify – causing additional damage to the oceans. The consensus is that we need to act now – and act carefully – to successfully balance the urgency of action with the safety of a well-designed study.

    One important part of the study design is its size. We know that the effects of an addition of Magnesium Hydroxide (MH) are temporary – the environment reverts to its previous state after an addition as the tides quickly dilute it and wash it away into the open ocean. We have purposely kept the addition amount small and the timeframe short.

    There are three potential risks that we have identified:

    •  If the addition of alkalinity leads to cloudiness of the water for an extended period, it can impede the growth of plankton. We plan to add the MH at a specific rate that is very far below the rate at which such clouding would occur.  Additionally, we will very carefully monitor the water for any clouding, and we will pause the study if any clouding does occur.
    • All natural minerals have the potential to contain other trace elements, which, if added in too high a concentration, may have an adverse effect on local plants and animals. We address this risk in two ways. First, before the material (a natural form of MH, called brucite) was shipped to the study site, we conducted an elemental analysis on the material to ensure that it meets environmental quality standards. Second, during each addition, we will monitor the local environment to determine if the trace metals in the area have increased. If we approach any limits, we will pause the addition.
    • If there is a buildup of alkalinity on the seabed, there is a small chance that organisms living there could be affected. To address this risk, we are starting with a baseline MH addition rate of less than 0.01% of the cooling water flowrate. Secondly, we will regularly scrutinize the seabed using cameras to look for any buildup. Finally, we will regularly take samples of the seafloor and measure the particles for alkalinity.

    Dr. Will Burt
    Chief Ocean Scientist

  • What uncertainties and/or risks need to be dealt with before you scale up your project?


    To Planetary, “deployment scale” means that we are operating at a full and safe capacity for ongoing continuous operations. We can envision that time in the future, but it is still a number of years away. We will only ever reach full operational scale when we are confident that the benefits to the climate, the ocean, and the community far outweigh any small and manageable risks that have not yet been eliminated.

    There are 3 main risks and uncertainties, posed here as questions, that must be addressed before we move to deployment scale, not only in Nova Scotia, but at any of our project sites:

    1. Is this process actually resulting in net atmospheric CO2 removal?
      This answer will have several components. First, any activity will emit some CO2, which needs to be considered. We will develop a high degree of confidence, combined with independent verification, of the total CO2 that our projects emit, all the way down to the emissions used to make the probes that we use for our measurements. Next, using real ocean measurements, we’ll demonstrate that the process is working. For example, we’ll need to show, with evidence, that alkalinity in certain parts of Halifax Harbour is ‘enhanced’, or increased, relative to the background concentration. Finally, we’ll share the results of numerical models that clearly indicate how much CO2 removal occurred because of the alkalinity enhancement. One specific risk here is that after alkalinity is added, the waters sink to the deeper ocean before completely absorbing the atmospheric CO2 that it theoretically could. Measuring that will be extremely challenging, so we will rely on high-quality models to estimate this potential ‘loss’ and work to minimise the uncertainty associated with that estimate. The methods themselves, and the results they provide, will be validated by third parties. For Nova Scotia, this numerical model is run by our Dalhousie colleagues, and is of extremely high quality.
    1. Is this process having any negative impact on the local ecosystem?
      Our approach to carbon removal is particularly promising because, in theory, it does not directly impact the biological system. However, we must look very closely for indirect impacts. Lab-scale experiments assessing biological impacts both here in Nova Scotia and around the world are very encouraging, and this diligent, university-driven science must continue as we begin to move into the field. To some degree, this search for impacts must be conducted across the entire ecosystem, but we will also follow the scientific community to target our search on the most critical and logical groups of organisms. Planetary’s approach here aligns well with the latest literature: we must closely monitor:
      • Particles (which can change the light environment)
      • Impurities (some of which can be harmful at high levels)
      • Acidity level or pH (we deacidify on purpose but need to stay within safe bounds)
      • The seafloor (where particles and metals might accumulate).
    1. Is the community generally supportive of deployment?
      Getting to deployment will take multiple field trials over multiple years, and communities must be with us every step of the way. We want to be very clear – there is not yet any agreement in place to deploy this process at scale in Halifax. At this time, we are simply investigating whether it might be technically feasible for that to be considered. In addition to technical capability and regulatory approval, we are committed to working with the communities here in the area to determine whether this process should be deployed, and, if so, under what conditions.

    Planetary hopes that the process is successful at reaching our goals of healing the ocean and restoring the climate – as well as delivering the many potential benefits to the community – but if the collective decision of local people is that the process should not be deployed here, we will not move forward.

    Dr. Will Burt
    Chief Ocean Scientist