The Manteo Prospect off the shore of North Carolina is an exploration target estimated to contain as much as five trillion cubic feet of natural gas (TCF), [1] potentially the largest domestic find of conventional natural gas since Alaska’s Prudhoe Bay in 1968.[2]

For comparison sake, Independence Hub in the Gulf of Mexico can access an estimated two TCF in proven natural gas reserves. [3] Independence Hub consists of multiple subsea wells that are tied back to one centrally-located host platform producing approximately 850 million cubic feet of natural gas per day.[4] Given than the Manteo Prospect appears to have access to a larger reserve of natural gas, it is reasonable to assume that the Manteo Prospect could produce as much as, if not more than Independence Hub.

Cape Wind is a proposed wind project for offshore Massachusetts in Nantucket Sound. The Cape Wind developers propose installing 130 wind turbines, each with a maximum capacity of 3.6 megawatts, standing 440 feet tall across an area of approximately 25 square miles.[5] Overall, the project is estimated to have a maximum delivered capacity of 454 megawatts based on a design wind velocity of 30 miles per hour and greater to a maximum operational velocity of 55 miles per hour. Based on the average wind speed of the Nantucket Sound of 19.75 miles per hour, however, the average generation capacity of the Cape Wind project would be approximately 182.6 megawatts.[6] At this capacity, the Cape Wind project would annually deliver about 1,600 gigawatt-hours of energy.[7]

To compare offshore natural gas production and wind energy generation, the potential energy production for the Manteo and Cape Wind projects has been converted to British thermal units (Btu). If the Manteo project produced as much as Independence Hub, and as noted above, this is every reason to believe it will, it would supply 320 trillion Btu of energy[8]annually, while the Cape Wind project would supply 5.4 trillion Btu[9]. Therefore, it would take about 59 Cape Wind developments to equal the energy output of the Manteo project.

Both natural gas and wind energy developments pose some oil spill risk if the facilities are damaged or destroyed. Natural gas is often produced in combination with condensate, a form of liquid hydrocarbon, and the tanks and equipment on the production platform hold lubricating oils and other fluids. The turbines and service platforms that make up a wind farm also contain lubricating oils and other fluids. The Manteo worst-case scenario listed below is based on the Independence Hub worst-case discharge of 10,795 barrels of oil.[10] The equivalent wind farm scenario of 98,058 barrels is based on estimates of the Cape Wind project. This includes 27,820 gallons from 130 turbines and 42,000 gallons from one electric service platform, or about 1,662 barrels of oil, multiplied by 59 to equal the annual potential energy production of the Manteo development.[11] While a larger offshore wind farm may require fewer service platforms depending on the design, for simplicity, we are assuming the same ratio of turbines to service platforms.

Manteo Natural Gas Development Equivalent Wind Farm

(59 Cape Wind projects)

Form of energy produced

Natural Gas Electricity

Annual potential energy production

320 trillion Btu 320 trillion Btu

Distance from shore

38.7 to 44.8 miles[11] 5.2 to 13.8 miles[12]

Number of facilities

One surface platform tied to multiple subsea wells 7,700 turbines

59 electric service platforms

Height of facilities

Platform: 105 feet[13] Turbines: 440 feet[14]

Visible from shore?

No Yes[15]

Area of development

1.2 acres

(0.002 square miles)[16]

944,000 acres

(1,475 square miles)[17]

Worst case oil spill volume

(Assumes complete destruction of all facilities)

10,795 barrels[18] 98,058 barrels[19]

Percentage of facilities destroyed to spill 10,795 barrels of oil

100 percent 11 percent

848 turbines and 6 electric service platforms, across 104,298 acres (163 square miles), or approximately 6.5 Cape Wind projects



[3] E&P, Independence Project, p. 10,





[8] Based on 1 cubic foot equaling 1,028 Btu

[9] Based on 1 kilowatt hour equaling 3,412 Btu

[10] – Pages 119 and 120, Tables A-3 and A-4

[11], Page 5-24



[14], page 7



[17]1.2 surface acres (page 7 of EIS for Independence Hub), 5053 subsea/seafloor acres (latter based on MMS high end for Independence Hub sea bottom impact of between 304 and 5,053 acres — high end estimate based on use of catenary mooring lines – p. 67 of EIS). EIS at:

[18] Based on 59 sites of 25 square miles each.

[19] – Pages 119 and 120, Tables A-3 and A-4

[20], Page 5-24

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