Getting Started

Artificial Upwelling Pumps for Ocean Carbon Dioxide Removal

Since 2005, our team of engineers and ocean scientists have designed, built, and tested our climate and ocean positive technology to fertilize phytoplankton, which absorbs CO2. Our objective with the following content is to provide a scientific and technical explanation for Artificial Upwelling Pumps for Ocean Carbon Dioxide Removal (CDR).

In reviewing possible risks of conducting artificial upwelling, Professor Andreas Oschlies from GEOMAR says the following: “There is essentially no environmental risk associated with small-scale field trials. For hypothetical large-scale deployment, local oxygenation of subsurface waters by translocation of surface waters and deeper waters will be accompanied with a translocation of nutrients and heat, likely leading to a cooling and enhanced biological productivity of surface waters. Enhanced productivity will eventually be followed by enhanced respiration and oxygen consumption that may to some extent offset the initial oxygen gain. Enhanced biological productivity will likely enhance the productivity of higher trophic levels including fish. There will be shifts in the ecosystem, the valuation of which is difficult, but with higher productivity in normally not over-productive waters, these will most likely be viewed positively. It cannot be ruled out that species of little commercial value or possibly even toxic algae may benefit more than others. Mechanisms of such ecological shifts are poorly understood and based on current knowledge there is little expectation that shifts will differ from natural shifts observed when moving from oligotrophic to more eutrophic conditions, such as usually found further onshore.”

We aim to review the following topics in describing the science and implementation behind our technology:

  • Physical footprint: our solution takes advantage of carbon, less constrained by arable land.  
  • Capacity: our technology has a path forward to being a meaningful part of any carbon removal solution (i.e., more than 0.5GT CO2/year by 2040). 
  • Durable: meaning it stores carbon permanently (more than 1,000 years).  
  • Verifiable: we use scientifically rigorous and transparent methods for monitoring and verification of CO2 sequestered.
  • Additionality: new net carbon being removed rather than taking credit for removal that would have occurred regardless.
  • Safety and compliance: we are legally compliant, responsibly, and actively engaging with the public to determine and mitigate possible risks and negative externalities.
  • Net-negative Lifecycle: overall, our Artificial Upwelling system results in a net reduction in atmospheric CO2

Scientific Basis

Technical explanation of Artificial Upwelling

Carbon fixation through plant production in the ocean is driven by vertical mixing of nutrient-enriched deep water into sunlit surface layers –achieving net carbon fixation above baseline and net carbon sequestration (CO2 “offsets”). Ocean gyres, particularly the North Pacific gyre, are areas with relatively low vertical mixing and strong vertical nutrient gradients. Horizontal spatial coherence is very high in these gyres, so measuring impacts of pumped upwelling are simplified. The vast gyre areas where conditions are similar suggest scalability of wave-driven pumped upwelling is substantially driven by the number and size of pumps deployed.

Figure 1. Phytoplankton bloom off New Jersey. Image source: Shorebeat.
Figure 2. Ocean Gyres. Image source: Science Learn

The key to producing net carbon sequestration in these low-nutrient, low-chlorophyll (LNLC) ocean gyres are the upwelling of deep waters containing nutrient concentrations greater than the dissolved CO2 concentration plant stoichiometry basis, i.e., the Redfield ratio.

In a 2008 paper, David Karl and Ricardo Letelier calculated the net sequestration potential from pump-driven upwelling using data collected at the long-term monitoring Station ALOHA in the North Pacific gyre near Hawaii. They calculated that upwelling of waters from 200 m or deeper provides excess phosphate, which triggers a sequence of nitrate and then phosphate uptake drove blooms of phytoplankton. The secondary phosphate bloom fixes more dissolved CO2 than is upwelled, resulting in net CO2 sequestration. Using the Karl-Letelier calculations, we build our pumps with the intake at 500 m to maximize the carbon fixed per unit area relative to the vertical length of the pump.

Table 1 from Karl and Letelier, 2008.
Table 2. Calculated net CO2 sequestered by one pump, adapted from Karl and Letelier’s 2008 data using volumes pumped from the current pump design (iron upwelling impact assumes zero additional tons CO2 sequestered in this table).
Table 3. Annual pumped volume by one pump.

In 2007, we conducted a sea trial of a 0.75m diameter by 152m deep upwelling pump to determine the upwelling flow rate, which was substantially identical to our current design except for dimensions. With triaxial accelerometers on the valve flappers recording open/close cycles, and temperature sensors top and bottom, we determined the time for deep cold water to surface. The outlet temperature sensor showed cold water arriving at 08:45:00, about 15 minutes after the first upwelling stroke. Dividing tube volume by elapsed time gives a flow rate of 0.078 m3/s.

Figure 3. Atmocean test data from 2007.
Table 4. Calculated efficiency and flow rate from our upwelling test in 2007. Analogous to the salt fountain discovery by Stommel & Arons, this test demonstrated the water inside the tube gains momentum, delivering about 61% greater vertical excursion than the waves.

Deployment Locations

Low-Nutrient, Low-Chlorophyll (LNLC) Ocean Gyres & Beyond EEZ Boundaries

The initial location will be in the open ocean, approximately 200nm from Oahu, Hawaii. The initial scale will be ten pumps spaced 720m apart (equal to two per square kilometer diagonally).

This location affords access to long-term baseline data from Hawaii Ocean Time Series (HOTS). The HOTS far-field data allows for robustly embedding the data from the pumping volume within a scientifically rigorous time-series data set, which allows for a better understanding of the uncertainty in the carbon sequestration calculations.

Figure 4. Location of the OBCS deployment site ~200nm from Oahu in the open ocean beyond US EEZ boundary.
Figure 5. Location of the OBCS test site within the broader context of the North Pacific. Note the size of the LNLC-ideal for demonstrating the net CO2 impact of artificial upwelling using wave-driven pumps. Figure courtesy Dr. Fei Chai.

Sequestration beyond the terrestrial biosphere

Artificial upwelling in the LNLC central gyres uses an area of the world with relatively low impacts from other human endeavors, and hence net CO2 sequestration through pump deployments has little secondary impacts.

Scale-up, Seasonality, and Additionality.

In the central gyres, horizontal scales are vast, i.e., on the order of 100’s to 1000’s of kilometers, while vertical scales are compact, 10’s to 100’s of meters. Vertical mixing, therefore, potentially generates significant impact with relatively small energy inputs. Furthermore, scalability is minimally constrained. While each float’s impact is spatially constrained to a few square kilometers, the systemic float program’s effectiveness is not limited until a vast number of floats have been deployed. See the “Scaleup” section on page 15 to calculate the scaling necessary to drive the sequestration offsets using artificial upwelling pumps to greater than 0.5 gigatons CO2 per year.

In the NPSG and other LNLC gyres, productivity is limited by nutrient scarcity – so all-new production from pumped upwelling is “additional.”

There is a slight latitudinal limitation within the NPSG LNLC area as sunlight is adequate through the entire year to drive phytoplankton blooms at least 30° N.

Figure 6. Winter bloom in North Pacific (Xing et al., 2020) demonstrating interactions of mesoscale atmospheric forcing on the upper water column resulting in export flux events.
Figure 7.4 – 2016 Estimated Upwelling Volume at NDBC #51001
Figure 7.4 – 2017 Estimated Upwelling Volume at NDBC #51001
Figure 7.3 – 2018 Estimated Upwelling Volume at NDBC #51001
Figure 7.4 – 2019 Estimated Upwelling Volume at NDBC #51001
Figure 7.4 – 2020 Estimated Upwelling Volume at NDBC #51001
Figure 7.5. 5 year average estimated upwelling volumes at NDBC #51001 2016-2020 – demonstrating sufficient wave action during all time periods to produce meaningful volumes.
More ocean heat = less natural upwelling. Slide provided by Ocean Scientist Dr. Fei Chai, University of Maine.

Permanence & Verifiability

Mean ocean age is over 1,000 year’s old.

In the North Pacific, the mean ocean age is over 1,000 years, thus qualifying our outcomes from this region as “permanent” according to the Stripe criteria.

Figure 8. Mean age of oceans. From “Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age.” S. Khatiwala F. Primeau M. Holzer Earth and Planetary Science Letters 325–326 (2012) 116–125.

Verifiability

Net production driven by the upwelling pumps will be measured by integrating the particulate organic carbon measured by the backscattering sensors on a pair of robotic profiling floats within
the pump patch and outside of the patch. The robotic floats are similar to the floats used in the ARGO program and equipped with the sensor set as used in the BIO-ARGO program.

These sophisticated instruments will allow for detailed monitoring of the water column’s physical and major biogeochemical parameters within the pump footprint and the outside baseline water column. The pumps
will be programmed for daily cycling, and profiling mission parameters can be modified to keep the floats moving with the pumps.

Figure 9. Biogeochemical ARGO’s measuring sinking POC from North Pacific wintertime phytoplankton blooms, by Dr. Fei Chai.
Figure 10. ARGO with SeaTrek Power Pack

By programming the floats to dive and resurface once per day rather than once per five or ten days, much higher resolution data is obtained, which captures many more productivity events triggered by the nutrients delivered to the sunlit upper ocean by our upwelling pumps.

A commercially available strap-on powerpack from SeaTrek operating on the ocean thermal energy principle provides near-infinite power for the BGC ARGO floats. This enables daily operating cycles essentially forever.

Figure 11. BGC-ARGO coherence within gyre (courtesy Dr. Fei Chai).

Governance

UN Law of the Sea & London Convention

Our interpretation is that we comply with the intent of the UN Law of The Sea and The London Protocol because we believe our technology is not adding any foreign substance to open ocean waters. However, we recognize that ocean-CDR is a developing field and we are prepared to comply as the issues are clarified.

Risks & Challenges

Transparency on the hurdles we face ahead.

Risks our project currently faces.

  • Societal rejection of ocean CDR due to outdated or incorrect information or political beliefs.
  • Corporate customer decisions against ocean CDR are based on faulty assumptions, lack of knowledge, or failure to acknowledge the much higher risk from their excess CO2 under business-as-usual.
  • Scientific reviewers’ reliance on outdated, incorrect, or obsolete papers, data, and information.

Durability

Modeled durability should exceed over 1,000 years, according to Dr. Stephanie Hensor (from NASEM webinar Q&A): “…the retention time depends on how deep the “extra” C may be penetrating and on the ventilation time scale of the region. For example, in the Pacific, ventilation time scales could be > 1000 years if C penetrates deeper than 1500m.” 

Please note that the most urgent time to reverse atmospheric CO2 is the next 80 years. Nearly all the CO2 sequestered by our upwelling pumps will remain in the mid and deep ocean over this most critical period. 

Furthermore, beyond this critical period, to the extent sequestered CO2 reappears in the upper ocean, assuming our pumps remain in operation in the region, some portion, perhaps most, of this CO2 will again be removed sequestered by freshly-grown phytoplankton in response to the nutrient upwelling. The typical approach of adopting a cut-off time when resurfacing CO2 will outgas to recognize the recurring outcomes from our pump’s upwelling deep nutrients, which trigger continuous blooms and CDR. 

Upper and lower bounds on durability claimed above.

Deepwater carbon has been radiocarbon dated at 5,000 years. Shallow particulate organic carbon can remineralize and resurface under 100 years, but phytoplankton blooms triggered by our upwelling recycle this. The process is continuous, so there is no “lower bound” (period).

Have we measured this durability directly?

As implementation of ocean CDR via upwelling is a new field of activity, we rely on David Karl and Ricardo Letelier’s data and analysis. 

Also, we look to the paper cited by Dr. Stephanie Henson – https://escholarship.org/uc/item/8jq8c83r

The durability risks our project faces.

Some exported CO2 is remineralized and, overtime may reappear above the thermocline. Since our pumps operate 24/7/365, the upwelling of nutrients is continuous; therefore, the CO2 making its way to the surface layer is reprocessed biologically and re-sequestered.

Until recently, there was uncertainty on measuring and validating net CO2 export, but this has now been answered by daily sampling using the biogeochemical Argo robotic floats as discovered by Dr. Fei Chai, under the procedures set forth by Dr. Ian Walsh.

How we plan to quantify the actual permanence/durability of the carbon sequestered by our project.

We can now directly measure both quantity and depth profile using the BGC ARGO’s as further explained by Dr. Ian Walsh and Dr. Fei Chai.

References

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Boyd, P.W., Claustre, H., Levy, M. et al. Multi-faceted particle pumps drive carbon sequestration in the ocean. Nature 568, 327–335 (2019). https://doi.org/10.1038/s41586-019-1098-2

Buesseler Ken O. et al., “Metrics that matter for assessing the ocean biological carbon pump,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.1918114117

Chai, F., Johnson, K.S., Claustre, H. et al. Monitoring ocean biogeochemistry with autonomous platforms. Nat Rev Earth Environ 1, 315–326 (2020). https://doi.org/10.1038/s43017-020-0053-y

Feng, E. Y., Su, B., & Oschlies, A. (2020). Geoengineered Ocean vertical water exchange can accelerate global deoxygenation. Geophysical Research Letters, 47, e2020GL088263. https://doi. org/10.1029/2020GL088263. 

Ginis, Isaac – University of Rhode Island Graduate School of Oceanography – unpublished report “”Investigation Of The Possibility Of Limiting Hurricane Intensity By Locally Reducing The Upper Ocean Heat Content Using Wave-Driven Deep-Ocean Pumps”, 2007. 

Hansell, Dennis A., CA Carlson, DJ Repeta, R Schlitzer “Dissolved organic matter in the ocean: A controversy stimulates new insights” Oceanography, 2009.

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Karl, David M., Ricardo M. Letelier, “Nitrogen fixation-enhanced carbon sequestration in low nitrate, low chlorophyll seascapes” MEPS 364:257-268 (2008) https://doi.org/10.3354/meps07547

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Sandia National Laboratories unpublished report “Model-based Assessment of ‘Down-welling’ Carbon Relocation Concepts”, 2019.

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Xing, X. et al. Seasonal variations of bio-optical properties and their interrelationships observed by Bio-Argo floats in the subpolar North Atlantic. J. Geophys. Res. 119, 7372–7388 (2014).