# Salinity gradient: Overview

Blue energy from where rivers meet the sea

Source page: https://www.materialinsights.org/energy/e_salinity/overview/

What this tile covers Energy released where fresh river water mixes with salty seawater ('blue energy'). Share of use 0% share of world energy supply (2025)

Share of world total energy supply, 2024 (latest year where noted). Denominator is the Energy Institute Statistical Review 2025 total of 592.2 EJ (physical energy content method). Flows EI omits (traditional biomass via WBA, solar and geothermal heat, food energy) are set against the same 592.2 EJ, so shares sum to slightly more than 100%. Only pilot plants exist (Fukuoka plant expected to give about 0.88 GWh a year), so the share rounds to zero. Source: [Japan's first osmotic power plant begins operations in Fukuoka](https://sj.jst.go.jp/news/202508/n0825-01n.html), Japan Science and Technology Agency (Science Japan).

#### Key facts

| **Origin** | Indirect solar |
|---|---|
| **Renewable** | Yes |

#### Included from the reference tables

- Salinity gradient (osmotic)

#### Also in Solar-derived flows
[Sun Sunlight](https://www.materialinsights.org/energy/e_sunlight/)[Wd Wind](https://www.materialinsights.org/energy/e_wind/)[H2O Water cycle](https://www.materialinsights.org/energy/e_hydro/)[Wv Ocean waves](https://www.materialinsights.org/energy/e_waves/)[Oc Ocean currents](https://www.materialinsights.org/energy/e_currents/)[OT Ocean thermal gradient](https://www.materialinsights.org/energy/e_ocean_thermal/)[Bm Biomass](https://www.materialinsights.org/energy/e_biomass/)[Amb Ambient heat](https://www.materialinsights.org/energy/e_ambient/)[Mu Muscle power](https://www.materialinsights.org/energy/e_muscle/)

Explore paths from here
 More on this tile in the tabs above: how energy resides, abundance, fluctuation in time, across the earth, impact on nature.

## Other sections

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