# Tides

The rise and fall of the sea caused by the pull of the Moon and Sun.

Source page: https://www.materialinsights.org/energy/e_tides/

Natural sources · Earth, gravity and atoms · No. 16

- Natural sources
- Origin: Gravitational / orbital
- Renewable: Yes
 Natural sources · Earth, gravity and atoms · Foundation · Energy

Tides can be forecast years ahead, yet their peaks arrive about 50 minutes later each day.

Chart: Illustration: Tides

##### Where it comes from

Chart: Map of where it comes from

The pull of the Moon and Sun raises the seas and drives currents; open ocean tides rise well under a metre, but some bays amplify them past 14 m.

##### Three things to know

1. Seawater is about 800 times denser than air, so even a modest tidal current carries a lot of power.
2. Planned barrages in India, Korea, the Philippines and Russia once totalled about 115 GW, but few were built.
3. Tidal energy comes ultimately from the Earth's rotation and the Moon's orbit, not from the Sun's heat.

##### The journey

1. 1 **Moon and Sun**Gravity tugs on the oceans
2. 2 **Tides**Water rises and currents race
3. 3 **Bays and straits**Funnel shapes amplify range and flow
4. 4 **Barrages and turbines**Dams across estuaries or underwater rotors
5. 5 **Electricity**About 1.1 TWh a year today

##### Go deeper pick a tab to open it in full

## Other sections

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