Marin fornybar energi Prof Peter M Haugan, Geofysisk institutt, basert på materiale fra Prof II Finn Gunnar Nielsen, Geofysisk Institutt

Transcription

1 Ny fornybar energi del 3: Marin fornybar energi Prof Peter M Haugan, Geofysisk institutt, basert på materiale fra Prof II Finn Gunnar Nielsen, Geofysisk Institutt

2 Outline General. Marine renewables Wind energy General Offshore wind Tidal energy Wave energy Thermal and salinity gradients 2

3 Marine renewable energy Source: European Science Foundation. Marine Board. Vision document on Marine Renewable Energy, 2010

4 The potential exceeds the demands. Source: IPCC SRREN,

5 Onshore wind farms Wind Farm, Kern County,Tehachapi, CA Midtfjellet vindpark, Fitjar 5

6 Energy in the wind Questions: What kind of energy is a wind turbine utilizing? How much energy or power is available for the wind turbine? 1 3 PAvail = ρ AV 2 How much power can be extracted? P max 16 = ρ AV 3 A 6

7 Offshore wind farms Example Sheringham Shoal, UK Facts: 315 MW of capacity Located off the coast of Norfolk, England 88 wind turbines, each 3.6 MW, Turbine blade length 52 meters Turbine tower height 80 meters Placed on foundations on the seabed Source: 7

8 Size of wind turbines Source: EWEA 8

9 Wind energy potential World Annual average wind speed at 10 m from NCEP, :http// 9

10 Wind variation with height A power law may approximate the increase of wind speed with altitude for neutral atmospheric conditions z u( z) = u( zref ) z ref z = 10m ref 0.1 open sea α = 0.15 flat land 0.4 urban area α Source: Stull,R. B., An Introduction to Boundary Layer Meteorology,

11 The standard wind turbine Source: 11

12 Wind energy potential Norway 12

13 Hywind utenfor Karmøy

14 Turbines, two basic principles: HAWT VAWT Horizontal Axis Vertical Axis 14

15 Wind power - On the move from land to deep water Costs Jackets Floaters Monopiles Water depth

16 Floating wind will compete with conventional bottom fixed solutions in a mature market 16

17 Power curve of a wind turbine (HAWT) 17

18 Yearly production capacity factor Capacity factor: C p = P rated AEP 365* 24 AEP: Annual Energy Production (MWh) Typical ranges: Onshore: Offshore: Full load hours : T = AEP P rated 18

19 Competitive prices euenergypost.eu 19

20 Summary Wind Huge resource potential. Maximum «capacity factor» 59%. Turbine sizes increases. Costs at grid parity at several locations. The industry moves offshore. 20

21 Tidal energy Main principles. Tidal barrage P= C ρgqh P Tidal stream P = C ρ AV P

22 Tidal range Source: IPCC SRREN

23 The Rance barrage (North Brittany), 1967 Up to 13.5 meters height difference 22km 2 reservoir 24 turbines, D= 5.3m, 10 MW each 600 GWh/y (average capacity factor of 0.29). Coastal & river device (peak flow > 10 times river flow) 23

24 Shihwa Lake Tidal Power Station, South Korea 254 MW / 552 GWh/yr (capacity factor 0.25), Operating from 2011 Average tidal range 5.6m 30km 2 lake 24

25 Challenge: Power from La Rance. Compute the yearly average power production from La Rance Optimum operation? P= C ρgqh Q P depends upon h 25

26 Tidal stream. Kvalsundet, Hammerfest, 2003 Max flow velocity 2.5 m/sec (mean 1.8 m/sec) 0.3 MW turbine (Test version) Diameter : 20m 0.7 GWh/y (average capacity factor of 0.27) 1 MW unit installed in Scotland, Orkney, Dec HS300, installed in Kvalsundet Prototype support structure 26

27 Summary Tidal Need large average current speed / large tidal differences Limited number of relevant locations Predictable 27

28 Ocean waves 28

29 Ocean waves 29

30 Resources Waves Average energy densities: kw/m wave front Source: World Energy Council Example: 50 kw/m, 30% efficiency: 130 MWh/ym 100TWh/y: 760km 30

31 Key principle for extracting wave energy Energy absorption requires a force working together with a velocity Work: Force*distance Power: Force*velocity Falnes: In order for an oscillating system to be a good wave absorber it should be a good wave generator. 31

32 Wave energy - main principles Source: Bedard(2006) «Overview: EPRI Ocean Energy Program» Presented to Duke Univerisity Global Change Centre. 32

33 Wave power converters. Installations in full / reduced scale Fred Olsen, Buldra. (Norway 2004-) Array of heaving buoys. Semisubmersible 33

34 The TapChan concept (Toftestallen, 1985). Wave focusing plus overtopping 34

35 Relative motion attenuator Pelamis (750 kw device) 35

36 Summary, wave energy Large energy potential A large number of principles proposed To extract energy you must generate waves Survivability drives costs 36

37 Ocean Thermal Energy Converter (OTEC) Utilizes difference in water temperature. Largest differences in tropical areas. Temperature difference at 20 and 1000m sea depth. Source: NREL

38 OTEC working principle Maximum fraction of energy available for work (Carnot cycle) T η = 1 T C H = 1 =

39 Possible layouts Source: OTEC Corporation Floating OTEC plant 39

40 New OTEC installed in August More, see e.g. OTEC overview, by L.A. Vega, Ph.D., 40

41 Salinity gradient, Pressure Retarded Osmosis (PRO) see IRENA (2014), NREL (2012) Key principle: Utilizes difference in salt concentration in two fluids. Creates a pressure difference over a membrane. Up to 26 bar pressure difference 41

42 Salinity gradient: Reverse Electro Dialysis (RED) Principle: Salt ions move through the membrane and creates an electrical potential. Use a stack of alternating cathodes and anodes. Source: Gert Jan Euverink, Wetsus Pieter Hack, REDstack 42

43 Salinity gradients potentials (IRENA 2014) 43

44 Summary Thermal and salinity gradients Thermal gradients: Relevant in tropical regions only Small scale testing ongoing Low efficiencies. Salinity gradients: Two principles: Generate pressure difference Generate electrical potential difference. Few sites world wide Tested in small scale Challenges in up-scaling (membrane) 44

45 Presentation title Takk for oppmerksomheten! Presenters name Presenters title Tel: