# Ocean currents: Abundance

A large flow, mostly in the wrong places

Source page: https://www.materialinsights.org/energy/e_currents/abundance/

What this tab covers How much of this energy there is: the natural flow or stock, the share that could be harnessed, and how much is used today, compared with world primary energy use (592 EJ in 2024).

The wind puts about 0.8 TW of work into the large-scale ocean circulation, about 4% of world primary energy use, and only a small part flows through currents fast enough to tap. The US Gulf Stream, the best-studied resource, has a technical potential of 49 TWh a year.
 A flow: renewed continuously

#### How much there is

| Measure | Value | Compared with world energy use | Note |
|---|---|---|---|
| **Wind work on the general (geostrophic) ocean circulation** | about 0.8 TW^[2](https://data-ww3.ifremer.fr/BIB/Wunsch_Ferrari_ARFM2004.pdf) | about 4% of world primary energy use (25 EJ a year) | Wunsch (1998); uncertain by at least a factor of two. About 80% enters in the Southern Ocean. |
| **Wind energy input to the Ekman (wind-driven surface) layer** | about 3 TW^[3](https://data-ww3.ifremer.fr/BIB/Wang_Huang_JPO2004.pdf) | about 16% of world primary energy use | Wang and Huang (2004): 2.3-2.4 TW at sub-inertial frequencies plus 0.5-0.7 TW near-inertial. Most of it is likely spent on turbulence and mixing in the surface layer rather than feeding large currents. |
| **Kinetic energy stored in ocean eddies (a stock, not a flow)** | about 26 EJ^[2](https://data-ww3.ifremer.fr/BIB/Wunsch_Ferrari_ARFM2004.pdf) | about 4% of one year's world primary energy use | Mesoscale eddy kinetic energy; the general circulation's own total is uncertain. |
| **Gulf Stream within the US exclusive economic zone: theoretical / technical** | 160 / 49 TWh per year^[4](https://www.energy.gov/sites/prod/files/2021/02/f82/78773_3.pdf) | about 0.1% / 0.03% of world primary energy use | Technical figure assumes 30% device efficiency; equal to 1.2% of US electricity generation in 2019. Other theoretical estimates range from 1 GW to over 200 GW; an older MacArthur Workshop estimate cited by the IPCC gave the Florida Current 25 GW of technical potential. |
| **World primary energy use (baseline)** | 592 EJ in 2024^[1](https://assets.kpmg.com/content/dam/kpmgsites/sg/pdf/2025/08/2025-statistical-review-of-world-energy.pdf) | 1 | Total energy supply, Energy Institute. |

Ocean currents are a small energy flow by planetary standards: the wind's work on the whole large-scale circulation is under 1 TW, compared with about 3.5 TW of tidal energy dissipated in the ocean and about 18.8 TW of average world primary energy use. Estimates are uncertain by a factor of two to ten, because the ocean's mechanical energy budget is poorly measured.

The tappable part is far smaller still. Even the US Gulf Stream resource of 49 TWh a year (about 5.6 GW average) is under 1% of the wind's work on the circulation. Theoretical estimates for the Gulf Stream range from 1 GW to more than 200 GW, depending on whether they count only the kinetic energy passing a line or the energy that could be removed before the current itself changes. No commercial ocean current plant operates today; the resource is at the research and prototype stage.

#### Sources

1. [Energy Institute Statistical Review of World Energy 2025 (74th edition)](https://assets.kpmg.com/content/dam/kpmgsites/sg/pdf/2025/08/2025-statistical-review-of-world-energy.pdf) Energy Institute (with KPMG and Kearney), 2025
2. [Vertical mixing, energy, and the general circulation of the oceans (Wunsch and Ferrari, Annual Review of Fluid Mechanics 36, 281-314)](https://data-ww3.ifremer.fr/BIB/Wunsch_Ferrari_ARFM2004.pdf) Annual Reviews (copy hosted by Ifremer), 2004
3. [Wind energy input to the Ekman layer (Wang and Huang, Journal of Physical Oceanography 34, 1267-1275)](https://data-ww3.ifremer.fr/BIB/Wang_Huang_JPO2004.pdf) American Meteorological Society (copy hosted by Ifremer), 2004
4. [Marine Energy in the United States: An Overview of Opportunities (Kilcher, Fogarty and Lawson, NREL/TP-5700-78773)](https://www.energy.gov/sites/prod/files/2021/02/f82/78773_3.pdf) National Renewable Energy Laboratory / US DOE, 2021

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_currents/index.md)
- [Overview](https://www.materialinsights.org/energy/e_currents/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_currents/correlation/index.md)
- [How energy resides](https://www.materialinsights.org/energy/e_currents/resides/index.md)
- [Fluctuation in time](https://www.materialinsights.org/energy/e_currents/time/index.md)
- [Across the Earth](https://www.materialinsights.org/energy/e_currents/geography/index.md)
- [Impact on nature](https://www.materialinsights.org/energy/e_currents/nature/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_currents/links/index.md)