Protecting Galapagos Marine Ecosystems from El Niño and Climate Change

While the cyclic devastation of El Niño events is natural and the coevolution within the Galapagos ecosystems has been shaped by it, El Niños are now increasingly combined with other stressors from human activity (Sachs, 2010): rising sea surface temperature (SST) due to anthropogenically caused global warming, worldwide overfishing that is depleting marine fish to the point of collapse if continued (Watson, 2001) , ocean acidification from increasing atmospheric CO2 and increasing local human inhabitants with their attendant pollution, disruption and introductions of non-native species and predators.

OTEC (Ocean Thermal Energy Conversion) is an proven technology that uses the difference in temperature between surface water and water at depth to drive an electric generator. In the pilot OTEC system proposed here, cold, nutrient-rich sea water pumped from a 1000m depth is expelled just below the surface, enriching ambient nutrient concentrations naturally available for algae growth. Since algae is the base of the food web for nearly all life in the oceans, this approach looks to modestly reinforce nutrient flow to the local food web, and provide a baseline when this natural flow is cut off, as during a severe El Niño event. The 1982-83 and 1998-99 El Niños killed approximately 70% of Galapagos Sea Lions (Galapedia, 2011), 50% of Galapagos Penguins (Biology, 2009), and up to 90% of Marine Iguanas (Steinfartz, 2007).

 
Galapagos marine species 5x3 300 dpi copy.jpg

A few of the well known species that call the Galapagos home. All of them depend on a web of life based on plankton, which in turn depend on adequate upwelling of mineral nutrients, which are severly reduced during El Niños.

Photos courtesy of Max Ruckman unless otherwise noted.

The cold seawater effluent and its depth of release would need to be closely monitored to ensure nutrient composition, acceptable CO2 off gassing, plume spread and effects on the ecosystem. This technology has been tested and modeled in Hawaii (Grandelli, 2010). OTEC effluent volume during non-El Niño years will be small compared to natural upwelling volume, and the goal - and challenge - will be to make it significant enough in severe El Niño years to avert extinction of some species. At the same time the Galapagos can be transitioned to a local, entirely renewable energy system at increasingly competitive cost that can keep this World Heritage site free of nearly all land based energy generation.

OTEC Provides Both Renewable Power and Marine Ecosystem Support

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Conceptual arrangement of OTEC platforms around the Galapagos Islands to provide renewable, zero carbon energy to local communities as well as nutrient rich mineral plumes (false color) to support plankton that are the base of the web of life offshore.

Key Points of the Proposal

• OTEC generators are sized with respect to overall population served, and positioned upstream of marine habitat. The project might start with one 5MW OTEC site at or near one of the areas shown with a submarine power cable to a nearby town that is still consuming diesel fuel in a comparable amount.

• OTEC platforms would double as National Park and Marine Reserve observation towers with a 16km (10 mile) unaided viewing radius to monitor park conditions and control poaching. Viewing radius will also be limited by weather conditions.

• An option of a circular artificial reef around the OTEC platform provides habitat and a resting place for species such as sea lions and birds that may be attracted to the area while foraging, though Galapagos Marine Iguanas and Galapagos Penguins will not venture out that far (approx.10 km from shore). The reef is a hollow, perforated compression ring anchored to the generator by tension cables similar to bicycle wheel construction. After years of service and marine accretion, the old reef could be towed away and submerged in shallow waters, possibly to restore some of the functions of the devastated reefs, though it cannot replace the coral species

• OTEC energy production efficiency increases with increasing sea surface temperatures, which helps to offset increased electrical demand during hot weather. SST’s are estimated to rise 1-3C this century in the equatorial Pacific (Sachs, 2010).

• Assuming successful prototyping, this system could be replicated and adapted to other island or coastal zonesroughly 20 degrees above or below the equator.

• While wind and photovoltaic power introduced to the four inhabited islands thus far deserve high praise, these systems will do practically nothing to lessen the combined stresses of El Niño and global warming on the local marine environment.

• This proposal is not intended to provide any carbon sequestration.

• Testing would be required to verify suitability of water from 1000m compared to that of naturally upwelled water.

 

Designing for Ocean Currents and Upwelling

SST Chlorophyll a.jpg

OTEC platforms are sized and arranges around the islands to maximize the distribution of the artifically upwelled nutrients.

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Galapagos Pop and Energy Demand.jpg
 
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Current Galapagos Power Requirements

Based on energy use in San Cristobal where a wind-diesel facility supplies 50% of the island’s power with 2.4 MW and 4,428 MWh/yr energy (e7 Galapagos/San Cristobal Wind Power Project, 2007), the total power demand per capita is approximately (2.4MW/0.50)/5633 people = 0.85 kW/person. (This disagrees with the above figures from 2000 with would give about 0.23 kW/person.)

Assuming approximately 0.85 kW/person and extrapolating for the total current Galapagos population:

Total power demand = (0.00085 MW/person)(18,780 persons, 2006) = 16 MW

Hypothetical Demand in 2100

While no growth would certainly be the best scenario ecologically, based on projected world population growth by the UN, little or no growth is very unlikely. Assuming for the sake of argument a population growth in the Galapagos of 200% by 2100 (United Nations, 2010)

Total energy demand in 2100 could be approximately 34,000 MWh/yr.

Total power demand in 2100 could be approximately 32 MW

This hypothetical demand in 2100 could be met by (3) 10MW OTEC platforms.

5MW OTEC Pilot Power Plant Cost

At 10km or less from shore $4,200,000/MW capital cost (Vega, 2002)

Cost pilot 5MW OTEC platform: 5MW($4,200,000/MW) $21 Million

Cost Comparison of OTEC Electrical Energy vs. Conventional

Estimated OTEC electricity cost $0.20 /kWhr (Makai, 2011)

Estimated current electricity cost in the Galapagos Islands $0.17 /kWhr

 
 

REFERENCES

  1. “Galapagos Sea Lion,” Galapedia.’ <http://galapedia.darwinfoundation.org/Galapagos_Sea_Lion> Accessed October 8, 2011.

  2. “Galapagos Penguin,” Biology 487, Winter 2009. <http://mesh.biology.washington.edu/penguinProject/Galapagos>. Accessed October 8, 2011.

  3. Steinfartz S, Glaberman S, Lanterbecq D, Marquez C, Rassmann K, Caccone A. (2007). Genetic Impact of a Severe El Niño Event on Galápagos Marine Iguanas (Amblyrhynchus cristatus). PLoS ONE 2(12): e1285. <https://doi.org/10.1371/journal.pone.0001285>.

  4. R. Watson, D. Pauly. (2001). Systematic distortions in world fisheries catch trends. Nature. 414(6863): 534–536. doi: 10.1038/35107050

  5. Hobson, E. S. (1965). Observations on diving in the Galapagos marine iguana, Amblyrhynchus cristatus (Bell). Copeia 1965:249–250

  6. Nihous, G.C. (2007). “A Preliminary Assessment of Ocean Thermal Energy Conversion Resources,” ASME J. Energy Resour. Technol., 129: 10-17.

  7. NASA, GSFC. (2011). Sea surface temperature images, <http://oceancolor.gsfc.nasa.gov/cgi/l3?per=SN&prd=SST&sen=A&res=4&num=24&ctg=Standard&date=21Jun2002. Accessed 20 October, 2011.

  8. Vega, L.A. (2002). “Ocean Thermal Energy Conversion Primer,” Marine Technology Society Journal, Vol. 6, No. 4, pp. 25-35.

  9. Ley, Debora. (2001). “An Assessment of Energy and Water in the Galápagos Islands.” Master’s Project Report, Building Systems Program, University of Colorado.

  10. Eólica San Cristóbal S.A - EOLICSA. (2009). “The e8 San Cristobal-Galapagos Wind Project. e8-GEF-UNDESA-UNESCAP Financing Sustainable Electrification South-East Asia Dialogues,” Bangkok, Thailand, September 8-10, 2009.

  11. United Nations. (2011). “Draft - World Population in 2300: Highlights,” <http://www.un.org/esa/population/publications/longrange2/Long_range_report.pdf> Accessed October 8, 2011.

  12. Clean Development Mechanism-SSC-Project Design Document. (2007). “e7 Galapagos / San Cristobal Wind Power Project,” United Nations Development Program.

  13. Sachs, J. and Ladd, S.N. (2010). Climate and oceanography of the Galapagos in the 21st century: expected changes and research needs. Galapagos Research 67: 50–54.

  14. Grandelli, P. and Rocheleau, G., 2010, “OTEC Plumes: NOAA OTEC Environmental Workshop, June 2010,” Makai Ocean Engineering, Inc.

  15. Makai Ocean Engineering, 2011, “OTEC - Ocean Thermal Energy Conversion,” <http://www.makai.com/e-otec.htm> Accessed October 9, 2011.

  16. Epler, Bruce, 2007, “Tourism, the Economy, Population Growth, and Conservation in Galapagos,” Charles Darwin Foundation. <http://www.darwinfoundation.org/english/_upload/Epler_Tourism_Report-en_5-08.pdf> Accessed October 9, 2011