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Replace all coal and oil electricity genergation with renewables and natural gas by 2025. Replace the natural gas with biomethane by 2040.



The Sargasso Sea is a natural seaweed forest ecosystem full of life and biodiversity.  We can manage new Sargasso Seas in coastal dead zones and open ocean “nutrient deserts” which produce biomethane.

In an ocean forest, sunlight powers the growth of seaweed which absorbs CO2.  Some of the managed seaweed forest is harvested every day into large microbial anaerobic digesters.  The hard-working bacteria separate the seaweed into biogas and plant nutrients.  The plant nutrients are dispersed into the forest to grow more seaweed.  Biogas is 60% bio-CH4 (identical to natural gas) and 40% bio-CO2.  Methane is easier to transport and store than hydrogen, making a biomethane economy more practical but with all the benefits of a hydrogen economy.

Ocean forests can produce 12 billion tons per year of bio-CH4 (600 quads or 176 million GWh) while storing 19 billion tons of bio-CO2 per year directly from biogas production when covering 9% of the world’s ocean surface.  That is 100% of U.S. Energy Information Agency projected world fossil fuel use in 2030, much more than E7 needs.


Category of the action

Reducing emissions from electric power sector.

What actions do you propose?

1.     Start the shallow water biogas and terrestrial fertilizer production business in Fiji.  Dr. N’Yeurt monitors adaptation programs for member countries of the University of the South Pacific.  He is investigating the best ways to mesh Fiji’s issues: excess terrestrial plant nutrients and seaweed in bays; expensive imported fuels; future climate refugees; etc. with Ocean Macroalgal Afforestation ecosystems.  PODenergy, Inc. is developing a business plan in concert with Dr. N’Yeurt’s research proposal and plans.

The Ocean Foresters team is also collaborating with researchers at Scuola Superiore Sant'Ann, Italy.  They are investigating ways to convert the excess plant nutrients and seaweed in Orbetello Lagoon into energy and terrestrial fertilizer.

2.   Develop open-ocean seaweed forests to replace natural gas with bio-CH4 while storing the bio-CO2.  We expect that developing open-ocean seaweed forests to reliably produce bio-CH4 for less than US$4 per thousand cubic feet will cost about $100 million spread over ten years.  Expect several more decades to expand the forests to completely replace natural gas, oil, and coal.

If we have a carbon dividend (see Action 3), E7 countries could price the storage operations slightly below the dividend rate but above costs to store CO2, initially.  They would subsidize the bio-CH4 cost to benefit their economies and increase market share.  That is, fossil fuel companies would be paying to price themselves out of business before they go after the ever more remote and expensive “reserves.”

Later (perhaps by 2060) fossil fuels may be sufficiently expensive and the quality of life in E7 countries high so that E7 countries can flip to subsidizing legacy CO2 removal and storage with profits from the bio-CH4 sales.


3.     Spread the shallow water ecosystems from Fiji to E7 and other countries.

4.     Deploy open-ocean ecosystems.

5.     Replace coal and oil with natural gas as quickly and completely as natural gas supply allows during the decade or two needed to ramp up bio-CH4 production.  Japanese methane hydrate recovery techniques and U.S. hydraulic fracturing (fracking) technology promises a global glut of natural gas.  In addition, global warming is destabilizing methane hydrates.  We need to extract and burn destabilized methane hydrates before they disassociate (melt).

Already, natural gas can be converted into any of the products essential to the world economy: jet fuel; diesel; gasoline; plastics; chemicals; hydrogen; etc.  Scientists are rapidly developing new ways to store and transport methane.

Natural gas is nearly twice the energy per ton of CO2 emitted as oil or coal.

6.     Implement a carbon dividend (tax, fee, credit, whatever).  With Ocean Afforestation, E7 countries could agree to a carbon fee because they could gain carbon storage income in excess of their carbon storage expenses from countries using fossil fuels. 

A carbon fee in excess of about US$20 per ton of CO2 can be used to store the seaweed forest’s bio-CO2 and subsidize the production of bio-CH4.  A carbon dividend of $50/ton of CO2 would allow E7 countries to drop the price of biomethane from US$4 per 1,000 cuft to $2.8 per 1,000 cuft.

When fossil fuel use stops, the carbon dividend drops to zero.  If E7 countries want to fund removal of legacy carbon, they sell the biomethane for $4.7 per 1,000 cuft.



Who will take these actions?

Action 1 will be taken by a combination of Fijians, PODenergy, Fiji government, individual philanthropists, and individual investors.

Action 2 will be taken by governments and non-profits funding universities, crowd investors, individual philanthropists, and individual and corporate investors.

Actions 3 and 4 will be taken by investors and corporations in the host countries.

Action 5 will be taken by free-market actors as they recognize sustainable, abundant, and relatively inexpensive biomethane reserves.

Action 6 will be taken by governments as they recognize that Ocean Macroalgal Afforestation makes a carbon dividend (credit, fee, tax, whatever) much less painful than continued “free” CO2 emissions.


Where will these actions be taken?

Action 1 is primarily in Fiji with support from developed countries.

Action 2 will be primarily several miles from any coast, possibly near the center of ocean gyres.

Actions 3 is in lakes, lagoons, and bays; any sheltered water.

Action 4 is in the open ocean.

Action 5 plays out in many nations, starting with those lacking coal, oil, and wind resources, but having coal and oil consumption infrastructure.

Action 6 makes unilateral sense for any country developing their Ocean Afforestation economy.


How much will emissions be reduced or sequestered vs. business as usual levels?

Ocean Afforestation scales beyond taking fossil electricity CO2 emissions to zero.

Ocean Afforestation scales beyond taking all global fossil CO2 emissions to zero.

Ocean Afforestation can address removing legacy fossil CO2 from the atmosphere.

What are other key benefits?

Food, negative carbon, biodiversity.  We can increase incidental but sustainable fish production to potentially provide 200 kg/yr/person for 10 billion people.

Especially when you factor in the droughts and floods of Climate Change, our expected 2050 peak of 9-10 billion people do not have the land surface or the fresh water to feed us with current food production systems.  We need marine agronomy, of which Ocean Afforestation is a subset.

What are the proposal’s costs?

Dr. N’Yeurt’s paper estimates $4 per 1,000 cubic feet of bio-methane exported from the Ocean Macroalgal Afforestation Ecosystem.  The University of Virginia life cycle assessment found the most likely ratio of energy output:input to be 4.  The cost of capturing and storing bio-CO2 is estimated at $16 per ton of CO2.

The University of the South Pacific needs US$1 million to design, build, debug, and operate two trial and training facilities for two years: a) a 2-ha sheltered saltwater biogas production facility in Laucala Bay; and b) a washed-up-on-beach freshwater biogas and terrestrial fertilizer production facility.

After debugging techniques and training operators at the 2-ha trial size, expanding the saltwater biogas and 7 MW capacity electricity production to a commercially viable 2,700-ha forest involves an investment of US$3 million.  Income from the electricity generation is expected to exceed expenses by US$2 million per year.  Income from the Carbon Development Mechanism, food, and other products has not been quantified.  We are still researching the minimum commercially viable washed-up-on-beach biogas and terrestrial fertilizer facility.  Once the sheltered water version of OMA is proven in Fiji, we export the ecosystem to the sheltered water of E7 countries.

Open-ocean operations are substantially different from sheltered water operations.  The more expensive but quicker approach is to develop open-water techniques in parallel with the sheltered water development.  We estimate needing US$100 million to design, build, debug, and operate the first commercially viable cluster of 10,000-ha open-ocean forests.


Time line

Year 1 –   Design, procure, and install equipment for the Fiji trial and training facilities.

Year 2 –   Debug operation of the 2-ha ecosystem, start engineering and permitting for 2,500-ha sheltered water forest.  Commence conceptual design and location selection for open-ocean trial facility.

Year 3 –   Engineer, permit, and procure equipment for 2,500-ha sheltered water ecosystem.  Design and build open-ocean trial facility.

Year 4 –   Install and commence operation of 2,500-ha sheltered water ecosystem.  Operate and debug open-ocean trial facility.

Years 5-8 – Ramp-up sheltered water installations to 1,000,000-ha per year (3,000 MW electrical capacities per year) for about ten years.  Design, build, operate, and debug commercial open ocean ecosystem.

Years 8-15 – Ramp-up open ocean installations to 100 million ha per year (20 quads per year) for about thirty years.


Related proposals

Geoengineering                “Rapid negative CO2 via seaweed forests” highlights the carbon dioxide removal (CDR) features of ocean afforestation.

Scaling renewables ….     “Fiji, then Indian Ocean Afforestation” highlights the inexpensive renewable energy and food production of ocean afforestation.

Shifting Cultures ….         “Mad Babies Saving Oceans” is a scenario wrapped into a video game employing the ocean afforestation ecosystem.

Shifting Cultures ….         “Rapid Planet Change” needs ocean afforestation, a holistic ecosystem to address global issues.

Electric power sector and Fossil fuel sector     “Save the methane!” suggests a carbon tax (credit, fee, dividend, …) to slow oil drilling, build the methane economy, and then ocean afforestation builds the biomethane economy.


N’Yeurt, A., Chynoweth, D., Capron, M.E., Stewart, J., Hasan, M.. 2012 Negative carbon via Ocean Afforestation.  Process Safety and Environmental Protection 90, 467-474

The above lists 32 references for the calculations involving the Ocean Macroalgal Afforestation ecosystem.  There are six supplemental information documents, some with more references:

OMA-MacroalgaeProduction&DensityCalcs2012 – 42 references

OMA-ProcessConcepts2012 – 2 references

OMA-GlobalCalculations2012,Table2 – 2 references

OMA-AlgalYieldsCalcs&Refs2012 – 45 references

OMA-N2O-EmissionsCalcs2012 – 2 references

OMA-ArtificialGeologicSeafloorStorageOfCO2,2012 – 38 references



Migliore, G., Alisi, C., Sprocati, A.R., Massi, E., Ciccoli, R., Lenzi, M., Wang, A., Cremisini, C., 2012 Anaerobic digestion of macroalgal biomass and sediments sourced from the Orbetello lagoon, Italy, Biomass and BioEnergy 42 69-77


Japan taps gas from methane hydrate, BBC News, March 12, 2013


Fracking: America’s Alternative Energy Revolution, John Graves, ChFC, CLU, Safe Harbor International Publishing, 2012