HURRICANE REDUCTION, FISHERIES ENHANCEMENT, & CO2 OFFSETS:
A UNIQUE ECONOMIC DEVELOPMENT OPPORTUNITY FOR COASTAL CITIES.
Philip W. Kithil, CEO
Imagine an economic development project for your city which brought new cleantech jobs, expanded both commercial and recreational offshore fisheries, and had the potential to reduce hurricane intensity and resulting wind damage.
Imagine Atmocean, Inc.’s wave driven upwelling pump technology - a simple technology which takes advantage of two very powerful, fundamental ocean physical properties. These are: 1) the deep ocean is colder than the surface; and 2) the deep ocean contains higher concentrations of vital nutrients such as phosphate, nitrate, iron, and other trace elements which are essential for marine growth.
The Atmocean pump employs a large surface buoy to capture wave kinetic energy to operate a valve at the bottom of a flexible tube stretching down hundreds of feet to this colder, nutrient-rich water. The buoy rises on wave upslope, closing the valve and bringing upward the the water inside the tube. On wave downslope, the buoy, tube and valve sink, opening the valve which forces more deep water into the bottom, while releasing the water from the top end of the tube. Over many wave cycles, a continuous flow of deep, cold, nutrient-rich water is gently brought to the upper sunlit portion of the ocean. This water mixes with the ambient water and produces a slight cooling of the upper ocean, while the extra nutrients help trigger photosynthesis, absorbing carbon dioxide (CO2) and generating oxygen (O2), in the process growing more phytoplankton.
The volume of the ocean surrounding each pump which is affected by this process is dependent on the pumping volume over time, since each pump stroke is driven by wave height, and the number of strokes per hour or day is governed by wave period. Other factors include pump efficiency, pump diameter, the depth of the upper mixed layer, the depth reached by the pump, and the number of pumps and spacing which occupy a particular ocean region. An approximation of the overall effect is shown below.
Based on 20 ocean tests of prototypes we have conducted since 2005, we know it is possible to induce modest, long-term beneficial changes to the upper ocean. This is particularly critical given the ocean’s heat absorption as our atmosphere warms.
This ocean warming is inducing a gradual slowing of critical biological processes, since the warmer surface waters resist mixing, which causes the surface nutrients to be fully absorbed by marine growth, but those nutrients are not replaced by natural upwelling of deeper nutrients. So a feedback loop ensues – more heating and stratification, less mixing, and a more sterile upper ocean.
We are confident our wave-driven upwelling pumps can help reverse this cycle. Some data from the aforementioned 20 ocean tests we have conducted in the Gulf of Mexico, Bermuda, California, and Hawaii, are shown below.
This data is supplemented by theoretical analysis by leading ocean and climate scientists. Professor Isaac Ginis from University of Rhode Island Graduate School of Oceanography who helped develop the ocean-atmosphere coupled hurricane forecasting model used by National Hurricane Center, has modeled how the more dense deep ocean mixes within the upper ocean. Professors Dave Karl from University of Hawaii, and Ricardo Letelier from Oregon State, have developed a theory relating to how precision upwelling of deep nutrients can beneficially induce more absorbtion of CO2 – in effect, storing our excess CO2 in the deep ocean using entirely natural processes. Dr. Wiebke Boeing from New Mexico State University has calculated the likely additional fish biomass produced by upwelling. And, Dr. Brian Von Herzen with The Climate Foundation has reviewed and verified these outcomes. We summarize below some of these important findings:
In this first slide, we have imposed a hypothetical pump array offshore of New Orleans and predicted the cooling of the upper ocean by factoring in the actual ocean temperatures and wave action as Katrina approached. As you can see, the upper ocean temperature is reduced by approximately one degree C. in the square area where the hypothetical pump array is located.
In this next slide, we have predicted how much the barometric pressure and windspeed of Katrina would have changed due to this imposed cooling. The modeled outcome shows peak winds reduced as much as 20 knots before landfall. Since wind damages are proportional to the cube of windspeed, this suggests up to 43% wind damage savings. Additional savings are likely from reduced flooding since rainfall and storm surge would also diminish.
In their landmark paper “Nitrogen fixation-enhanced carbon sequestration in low-nitrate, low-chlorophyll seascapes” (1), Karl and Letelier propose that precision upwelling of deep ocean nutrients in certain ocean regions could trigger both a primary phytoplankton bloom, and a second bloom. Whereas the effect of the primary bloom on dissolved CO2 levels in the upper ocean would be “break-even” – as much CO2 brought upward as is absorbed – with the second bloom, significant net export of CO2 is achieved. In this context, net export means the biological processes absorbs more carbon than is brought upward by the pumps.
Since the process is highly dependent on nutrient ratios which vary by depth, Karl and Letelier calculate the expected net export based on known conditions at Station Aloha, about 100 miles north of Oahu, Hawaii. To test their hypothesis, in June 2008 Atmocean participated in a test of three pumps reaching down to a depth of 300m. The experiment can be viewed by clicking on “Discovery Channel Hungry Oceans” at www.atmocean.com
Finally, we have calculated the estimated net fish biomass increase resulting from our upwelling pumps. Based on the widely-accepted “Redfield Ratio” which governs the molecular ratio of carbon
(on average, C:N:P = 106:16:1), given nominal wave height of 3m in the open ocean, we expect about 1.5 metric tons annual new production of fish.
Given these impressive results from both theoretical aspects, and from ocean tests, is it practical to deploy these pumps in sufficient quantity to make a difference?
The practicality discussion resolves into a dozen subtopics summarized below:
1. Are they easily deployed?
As I mention in my introduction to the Hungry Oceans program, the preferred deployment technique is to spool the flexible tube around the buoy, attach the valve, then drop the entire pump into the water. The heavy valve sinks, filling the tube with water as it unspools off the buoy. When full design depth is reached, the pump is positioned vertically and immediately begins to operate with each wave cycle. For a 160m (500 foot) deep pump, deployment takes about 3 minutes.
With this technique, the boat deckspace needed by each pump enroute to the deployment site is just the buoy sitting on top of the valve, as seen in this photo of a 30” diameter by 500’ deep pump during one of our Bermuda tests. With a somewhat larger 1m diameter and 2m long buoy, we estimate 1,000 pumps should fit on a 25m by 80m ocean-going barge.
Upon reaching the deployment site, pumps are tossed overboard one after the next, automatically unrolling as the vessel moves forward. Assuming a 12 knot (~24 km/h) forward speed, and desired 333m spacing (3 per km), two 167km long rows each with 500 pumps could be deployed in about 7 hours.
2. Production and assembly?
Given the bulkiness and relatively light weight of the buoy, valve, and tube components, it is most cost effective to produce and assemble the pumps close to the port from which deployment (and monitoring) will occur – rather than mass produce elsewhere and incur expensive shipping costs. This suggests an economic development opportunity for the port cities that take on this project to mitigate the effects of global warming on their adjacent ocean while improving fisheries, generate CO2 offsets, and gain some protection against hurricanes.
3. Effectiveness of the array?
According to our modeling of Katrina and Rita, in one day under hurricane-wave height conditions, we see ~1 deg C decrease in upper ocean heat content. A key feature relates to wave heights - as the storm moves toward the pump array, the bigger waves generate more pumping and more cooling.
Our standard pump will come with a flasher light, and a GPS with satellite uplink so we know constantly where each buoy is located. In addition, we expect to install additional instruments on the buoy and on the tube & valve to capture very detailed air & ocean data as well as ocean biomass data.
5. Recovery & Control Issues?
Since each the tube contains hundreds of m^3 of water, so it is necessary to open the valve at the bottom first, before pulling in the buoy-tube-valve. We now have a technique which allows this buoy-first retrieval of each pump.
As to controlling the pumping, because the pumps rely entirely on wave kinetic energy – the volume of upwelled water is variable and sporadic, closely mimicing existing natural process. However, if further testing suggests additional control features are desired, using the satellite uplink communications already on each buoy, we can remotely enable/disable the valve.
This is the most challenging aspect of this project, and we have engaged JP Kenny Inc. of Houston, the premier undersea engineering firm for the offshore oil & gas industry, to assist in designing appropriate moorings. A likely technique will be to install seafloor moorings at each end of each row of pumps.
7. Location of Rows, and Depth of Pumps?
For the hurricane intensity-protection application, the location of the rows of pumps need to be in sufficiently deep water so 10 deg C or colder water can be reached. In the Gulf in summer this is quite shallow - 100m in some areas. The closest pump rows should not be more than about 50km from the coastline, because the storm could re-strengthen if it exited the cold patch and hit warm water again before landfall. More analysis is needed to ascertain this level of optimization.
This also is subject to further optimization studies, however we estimate a pump density of two to four pumps per km should be sufficient.
Cooling the upper ocean by one degree C. reduces evaporative energy powering hurricanes, saving up to 50% from wind and flood damages. Upwelled ocean contains higher nutrients, increasing phytoplankton, with increased fish population up to 1,500 kg/pump/year. This induces more absorption of CO2, generating 60 tonnes/year offsets for sale on the climate exchanges.
Assuming 3m diameter by 100m deep pumps spaced 500m apart and extending seaward in a square pattern 100 km on a side, 40,000 pumps are needed. At $3,000 deployed cost for each pump, the total investment is $120 million. This amount can be defrayed by proceeds from fish enhancement, revenue from CO2 offsets, and by insurance savings due to lower risk of hurricane damages.
With Atmocean pumps deployed offshore from the coastal city, commercial and recreational fishing is enhanced, storm damages reduced, global warming abated, and jobs created.
In conclusion, we propose that deploying sufficient numbers of Atmocean wave-driven upwelling pumps offshore from coastal cities will generate multiple ecological benefits while providing a new and important economic development activity for the city.
1. “Nitrogen fixation-enhanced carbon sequestration in low-nitrate, low-chlorophyll seascapes”,
David M. Karl, Department of Oceanography, University of Hawaii, Honolulu, Hawaii 96822, USA, & Ricardo M. Letelier, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA. MARINE ECOLOGY PROGRESS SERIES 10.3354/meps07547.