1. Tidal current energy From water currents to electric energy
Johan Forslund 1 1

2. Chapter 1: Renewable energies
Marine Current Power
Chapter 2: Marine Current Power
at Uppsala University

3. The road of electricity production and consumption:
Transform and consume
Transform and transmit
Convert to electricity
Power absorption
Resource

4. Chapter 1: Renewable energies

5. Intermittency in renewable Energy
Intermittency is the time scale of natural variation for different renewable energy sources that we can not regulate.
Solar radiation – may vary within seconds as well as during day and night, summer and winter
Wind – may vary within minutes, seasonal changes
Wave – May vary within hours, seasonal changes
Tidal – tidal cycle of twice a day
Hydro - stock pile energy, seasonal changes 5

6. Technology for tidal current energy conversion – turbine concepts
Vertical axis
Horizontal axis
Oscillating hydrofoils
Horizontal axis
Kobold turbine (Italy) Operating since 2001
Power= 25 kW
Hammerfest Ström
(Norway)
Operating since 2003
Power = 300 kW
The Stingray (UK), briefly operated during 2003, 150 kW
Open Hydro
(Scotland)
Deployed 2009
1 MW 6

7. The tidal barrage La Rance
Photo: Wikipedia
21st July 2017:
Low tide at 00.09: m
High tide at 05.48: 10.7 m
Low tide at 12.40: 2.6 m
High tide at 18.17: 11.20 7

8. The tidal barrage La Rance8
Photos: Johan Forslund

9. The tidal barrage La Rance
Kaplan-
turbine
Photos: Johan Forslund 9

10. The tidal barrage La Rance
Photo: Johan Forslund 10

11. Tidal resource – Sites for tidal barrages
Mean Tidal Amplitude (m)
Basin Area (km2)
La Rance, France 4
22.5
Annapolis Royal, Nova Scotia
3.2 6
Severn Estuary, Great Britain
420
Sihwa Lake, South Korea 30
Bay of Fundy, Canada
5.5
29000
Compare with one nuclear power plant (One Ringhals ~6.5 TWh/year) and
Number of homes it supplies
Electric Energy [TWh/year]
# of nuclear power plants
# homes
(thousands)
La Rance, France
0.54
0.083
167
Annapolis Royal, Nova Scotia
0.05
0.008 16
Severn Estuary, Great Britain
6.67
1.026
2067
Sihwa Lake, South Korea
1.07
0.165
331
Bay of Fundy, Canada
871.68
301220 11

12. Chapter 2: Marine Current Power
- Uppsala University

13. The Söderfors Site - Marine Current Power (MCP) at UU
The concept is focused around a vertical axis turbine and a direct drive PM generator
- a simple and robust system with few moving parts
Vertical axis turbine
Generator 13

14. The experimental site in Söderfors14

15. The MCP generator 15

16. The MCP turbine 16

17. Thank you for your attention
Pictures and information about the companies and their
prototypes can be found at the following websites
Marine current turbines -
Open Hydro -
Atlantis -
Kobold Turbine -
Lunar Energy -
Hammerfest Ström -
Clean Current -
Race Rocks -
Swan Turbines -
Verdant Power -
… and there are several more prototypes around! 17