Ocean Upwelling To Restore The Oceans, Feed The World, And Stop Global Warming
Summary:
Artificial ocean upwelling can restore the oceans, feed the world, stop global warming, and pay for itself. Ocean upwelling brings cold nutrient rich water to the surface and can increase ocean productivity by up to ~10x. This would restore the oceans and dramatically increase fish and whale populations beyond pre-human levels. Via the cooling benefit it can also prevent coral bleaching and hurricanes. Combined with increased fishing and large scale seaweed farming it enables healthy low-cost high protein diets for all. By displacing a substantial fraction of terrestrial farming it enables the restoration of natural habitat and biodiversity, substantially mitigating our mass extinction and stopping global warming.
How it works:
The upwelling device is a suspended rotor that is pumped by wave energy, the blades flap up and down as they go around, powered by the vertical motion of the surface wave-following buoy. The rotor creates a jet of water that extends up towards the surface, looking and functioning similarly to a ceiling fan, but with an upward flow. Solar energy, wind energy, current energy, and other energy sources can be added to increase the flow rate and enable operation when wave energy is low. In many places wave energy is reduced during the summer when the need for upwelling is greater and alternate energy sources can help compensate for this, although this adds cost. Power can be added by mechanically pumping the rotor via the tether or by powering thrusters on the blade tips. With blade bridling that better distributes loads the upweller costs and scales similarly to wind turbines and rotor diameters as large as 200 meters are possible. The rotor operating depth might typically be 1 to 5 times the diameter of the rotor and operating depths as great as one kilometer are possible, although even in the deep ocean primary benefits are achieved by around 150 to 250 meter depths. Performance varies widely by location, mostly depending on available energy and the power needed to pump from depth against the ocean density gradient, however typical numbers at depth might be around $1,000/kW and 1m3/s/kW. A 1GW upweller farm might cost on the order of a billion dollars and have a collective flow rate equivalent to roughly 3% of the Gulf Stream - this technology economically scales to have global impact. With anchoring the upweller can be powered by ocean currents, deflecting them into upwellings. In the deep ocean cyclic control enables station keeping without anchoring, the rotor pull being steered so as to maneuver the upweller with high thrust at low speed. The rotor can be constructed from a wide range of materials including plastics, composites, and metals. Downwelling can also be accomplished by inverting the bridle structure. Much greater technical detail and video of it operating is available here.
The oceans are nutrient deserts:
The photic zone, defined by solar radiation reducing to 1% of the surface level, can extend down to a depth of 200 meters. Phytoplankton in the photic zone generally grow and absorb nutrients before sinking below the photic zone, depleting the surface of nutrients. The net result is that the ocean surface is mostly a nutrient desert while there are effectively unlimited nutrients just below the photic zone. Natural upwelling zones are highly productive and suggest that artificial upwelling could increase ocean productivity by ~10x. Eastern boundary upwelling systems cover less than 1% of the global ocean surface but provide up to 7% of the global marine primary production and 20% of the world’s capture fisheries. Coastal continental shelf areas, which cover ~7% of the world’s oceans, are more accessible to fishing and average up to around 120 meters in depth, which further mitigates nutrient escape below the photic zone. Nutrients gradients on the continental shelf are still generally sufficient for substantial upwelling biological productivity benefits.
Restoring the oceans:
The total wild fish catch is around 130 million metric tons per year. This has substantially impacted the health of our marine ecosystems, including greatly reducing the number of whales that the Earth’s oceans can support. This has also resulted in the continual nutrient depletion of surface waters, which can have an even more severe impact, collapsing ecosystems in some cases. Upwelling allows us to restore ocean surface nutrients to a level substantially above pre-human levels. It enables us to restore fish stocks and even whale populations beyond pre-human levels while also increasing wild fish catches. The increased income generated from boosting wild fisheries can revitalize depressed fishing industries and more than cover the costs of upweller deployments. Unfortunately there are challenges in closing the business case because the ocean is a commons where the benefits of upwelling are available to all independent of who paid for it. A collective interest group, which might be a local government or representative fisheries body, is needed that has a way to finance the collective benefits of upwelling.
Algal blooms are a serious downside risk of artificial upwelling that needs to be carefully managed. Under ideal conditions some phytoplankton can double in mass each day and they might only live a few weeks. A sudden boost in nutrients can lead to an algal bloom that grows much faster than the animal populations that consume it. This unbalances the ecosystem, resulting in a large mass of dead algal biodegrading on the seafloor that removes oxygen and suffocates many species. Reefs can be very sensitive to this. Toxic algal blooms can also result from unbalanced ecosystems and in some cases high nutrients can create phytoplankton blooms that can deprive reefs of sunlight. It is important that nutrient upwelling be deployed in a careful and gradual manner that does not exceed the ability of the local ecosystem to grow and absorb the increased nutrients while maintaining equilibrium. In some scenarios upwelling or downwelling can be used to mitigate deoxygenation by increasing vertical mixing. All upwelling will necessarily be balanced by downwelling elsewhere, and vice versa.
Food production:
Around 15% of animal protein comes from aquatic animals and while a little over half of this comes from farmed sources wild caught fish meal and fish oil makes up a substantial proportion of animal feed. Upwelling can dramatically boost wild fish production and this could have a substantial impact on global diet. If the global population stopped eating land based animal protein required farmland would be reduced by around 75%. Similarly, substituting ocean produced animal protein for land based animal protein could stop our mass extinction and global warming. As previously mentioned, financing upwellers for increasing fish stocks is difficult due to the lack of ocean property rights. One way around this is to integrate upwellers into terrestrial scale offshore seaweed farms, which are nearing a commercial tipping point. Seaweed is already a $20 billion/year industry. Upwellers are like Haber Bosch for the oceans and they can potentially increase seaweed yields by around four times. This yield increase pays for upweller integration many times over. Seaweeds already have higher photosynthetic efficiency than the most efficient plants, up to 6-8%, and are capable of very high yields. Most animals, including people, can thrive on up to around 20% seaweed in their diet. Beyond this desalting is needed. Seaweed farming can directly displace a large fraction of terrestrial farmland, enabling large scale reforestation which can avert a mass extinction and stop global warming. But this also closes the nutrient loop. Nutrients are extracted from farmland in the form of food and released via wastewater into the oceans. Returning these nutrients to the land via seaweed based animal feed closes this loop and avoids the need for inorganic fertilizers. Unlike land based farming, ocean farming improves and restores the natural ecosystem. Seaweed farms become fish nurseries and the upwelling benefits diffuse out into the larger ocean, helping to restore them. Large scale seaweed farming using upwellers enables globally sustainable high protein food production that does not displace natural habitat.
Direct climate benefits:
The upweller has direct climate engineering benefits. The ratio between power used and cooling water pumped to the surface can be as high as 1:100,000, that is, a single wind turbine sized 10MW upweller averaging a flow rate of 10,000m3/s might deliver 1TW of surface cooling. This can have a substantial impact on local climate. San Francisco fog, caused by natural upwelling offshore, provides a good example of what this might look like. A cool offshore environment and a hot interior increases anabatic wind flows that can draw humidity inland. Upwellers can be used to control and guarantee ocean currents, and to cool surface waters to stop hurricanes. They can be used to shield ice floes from warm currents, slowing melting and the receding of glaciers. Upwellers can also be used to flush out polluted bays and restore their ecosystems, pumping in deep clean water on the incoming tide which forces warm polluted surface water to leave on the outgoing tide. Upwellers can be used to directly mitigate some of the more extreme localized tipping points associated with global warming.
Current Status:
The upweller technology was developed and proven with the support of ARPA-E. As previously stated the upweller commercialization suffers from the tragedy of the commons - it is difficult to generate direct revenue for collective benefits. However, as aquaculture scales and the need for cool nutrient rich water increases this is likely to change. Upwelling may also find local funding for restoring marine ecosystems and fish stocks for local fishing industries. A free and open non-commercial license is available and we are encouraging commercial technology licensing. This technology licensing website also contains far greater detail on the upweller technology, including applications and a relatively comprehensive design document.