OCEAN ENERGY HOW THE OCEANS TURN OUR LIGHTS ON? ANTÓNIO SARMENTO 21 NOV 2016

Transcription

1 OCEAN ENERGY HOW THE OCEANS TURN OUR LIGHTS ON? ANTÓNIO SARMENTO 1 21 NOV 2016

2 THE OCEAN: A HUGE THEORETICAL RESOURCE 275,500 TWH/Y Tidal Tidal stream: energy in fast flowing tidal currents (2,200 TWh/y) Tidal range: energy from the difference between high and low tides (300 TWh/y) Waves (44,000 TWh/y) Ocean thermal energy conversion (OTEC): temperature differential between cold water from the deep ocean and warm surface water (50,000 TWh/y) Hydrothermal vents Salinity gradient: pressure differential between salt and fresh water (osmotic energy) (20,000 TWh/y) Offshore Wind: tipically a Wind Resource, but in fact it is also a Marine Energy Resource (176,000 TWh/y) Marine Biomass: macroalgae cultures to produce bio-fuel World Energy Consumption: 140,000 TWh/y 2

3 Scale of the resource assessment When discussing energy potential it is important to clearly define the limitations included Theoretical Resource - A top level statement of the energy contained in the entire resource Technical Resource - The proportion of the theoretical resource that can be exploited based on existing technologies Practicable Resource - The proportion of the technical resource that can be exploited after removal of physically impracticable areas for deployment Accessible Resource - What can be exploited after consideration of external constrains (competing uses, environmental protected areas, etc) Economic Resource - In general only part of the Accessible Resource may be commercially attractive at a particular point in time depending on market conditions 3

4 THE OCEAN: A RELEVANT MARKET RESOURCE Tidal Tidal stream: energy in fast flowing tidal currents ( TWhe/y) Waves ( TWhe/y) Ocean thermal energy conversion (OTEC): temperature differential between cold water from the deep ocean and warm surface water (small) Tidal range: energy from the difference between high and low tides (small) Salinity gradient: pressure differential between salt and fresh water (osmotic energy) (122 TWhe/y) Offshore Wind: tipically a Wind Resource, but in fact it is also a Marine Energy Resource ( TWhe/y) Marine Biomass: macroalgae cultures to produce bio-fuel (NA) World Electrical Energy Consumption: 14,000 TWhe/y 4

5 LONG-TERM MARKET POTENTIAL DISTRIBUTION OF OCEAN ENERGY RESOURCES Wave: ES: TWh/y FR: 245 TWh/y US: 1300 TWh/y UK: 365 TWh/y IE: 575 TWh/y NO: 400 TWh/y PT: 184 TWh/y Others: AU, CL, NZ, CA, SA, etc. Tidal resource UK: >340 TWh/y US+CA: 1700TWh/y JP: TWh/y CN: 900TWh/y Others: FR, IE, AU, CL, KR OTEC resource More than 98 countries in tropical waters Salinity resource Main rivers mouths around the globe: Zaire: 500 TWh/y Ganges: 219 TWh/y Mississipi: 158 TWh/y Rhine: 18 TWh/y Etc. 5 *TWh/y represent only theoretical resources. From that only a small portion (0-10%) will be commercially available, depending on the locations. For comparison, world electricity demand is TWh/y, Portugal aprox. 50TWh/y.

6 OCEAN ENERGY TECHNOLOGIES SCHEMATIC REPRESENTATION OF THE 4 OCEAN ENERGY TECHNOLOGIES Wave Tidal current OTEC Salinity gradient 6

7 OCEAN ENERGY TECHNOLOGIES COMPARISON OF TECHNOLOGY READINESS LEVELS TRL TRL 1-3 TRL 4 TRL 5 TRL 6 TRL 7 TRL 8 TRL 9 DOE TRLs description Active R&D is initiated Basic technological components are integrated The basic technological components are integrated with reasonably realistic supporting elements in a simulated environment. Model/prototype is tested in relevant environment Prototype near or at planned operational system Technology is proven to work - Actual technology completed and qualified through test and demonstration. Actual application of technology is in its final form - Technology proven through successful operations. 7

8 SUMMARY OF LESSONS LEARNT TECHNICAL COMPONENTS Failures in systems / processes considered standard is very common (attention shifted to those that foresaw to be more problematic) Reduced reliability of Standard components in non-standard applications non-standard components / innovative systems, standard components with flaws not easily explained or resulting from different water properties in different locations; Technologists with limited technical and financial capacity very pressed for time and expectations High installation and O&M costs in marine operations (see next slide) 8

9 LCOE (c /kwh) Instaled capcity (GW) COSTS & FINANCIAL SUPPORT COST REDUCTION AND LCOE EVOLUTION In wave, highest cost reduction is expected in: O&M ++ Structure ++ Installation + PTO + In tidal, highest cost reduction is expected in: O&M +++ Installation +++ PTO ++ Structure ++ Station keeping Wave - Capacity Tidal capacity Wave - LCOE Accelerated Wave - LCOE BAU Tidal - LCOE Accelerated Tidal - LCOE BAU Source: Carbon Trust 2011

10 Maturity of Technologies Tidal barrages Ocean waves and tidal currents technologies Salinity gradient technologies OTEC Technologies Mature technology, despite limited applications. Likely to have significant impact on local ecosystems Significant number of technologies being developed worldwide: some of these technologies are at or near fullscale development and undergoing sea trials Early stage R & D; demonstration prototypes operational Advanced stage of R & D 10

11 OTEC TECHNOLOGY TECHNOLOGY AND MAJOR COMPONENTS Major components: Cold water pipe (CLP) Warm water pipe Warm and cold water discharge pipes, used to return the cold and warm water after heat has been extracted Heat exchangers (closed-cycle only) Evaporators and condensers - to transfer heat between cold and warm waters and the working fluid Platform base for all OTEC operations Platform/pipe interface Mooring system Pumps, turbines and generators Power cable 11

12 OCEAN ENERGY: TOWARDS A STRATEGIC PERSPECTIVE OTEC TECHNOLOGY OTEC ENERGY: CONTRIBUTIONS AND CRITICAL ASPECTS State of art and critical aspects OTEC concept utilizes the differences in temperature, T, between the warm (Tw 22 C to 29 C) tropical surface waters, and the cold (Tc 4 C to 5 C) deep ocean waters available at depths of about 1,000 m TW potential market for OTEC (electricity and desalinated water) Ninety-eight nations with access to OTEC, also there is a market for industrialized nations to manufacture and supply equipment Developments did not proceed beyond experimental plants, less than 0.25 MW. Need to build a pre-commercial plant sized around 5 to 10 MW to establish the operational record required to secure financing for the commercial size plants. Lack of realistic determinations of the costs and the potential global environmental impact of OTEC plants. Several configurations for OTEC plants have been proposed: floating to land-based plants; primary candidate for commercial plants: floating plant close to land 12 WORKING PROGRESS

13 SALINITY GRADIENT TECHOLOGIES 4 TECHNOLOGY TYPES, BUT ONLY 2 AT RELEVANT TRL Membrane Based Non Membrane Based Pressure- Retarded Osmosis (PRO) Reversed Electrodialysis (RED) Vapour Compression Hydrocratic Generator Feasibility studies in 2007 Patented in

14 OCEAN ENERGY: TOWARDS A STRATEGIC PERSPECTIVE SALINITY GRADIENT TECHNOLOGY OSMOTIC POWER: CONTRIBUTIONS AND CRITICAL ASPECTS State of art and critical aspects Small market size (15,2 GW 122 TWh e /y) if based in natural fresh water sources, possibly significantly larger if urban disposable waters or urban non-treated waters can be used. Two technologies available: Pressure Retardated Osmosis (PRO) and Reversed Electrical Osmosis (RED). PRO much more interesting as uses same approach as extensively used Reversed Osmosis fresh water process. 10 kw, m 2 membrane area prototype by Statkraft in 2009 suggests PRO at TRL 7. Economic competitive PRO requires membranes to go from 1 W/m 2 to 7 W/m 2 (5 W/m 2 is expected in the near future). Water pre-treatment level and membrane modules are also major concerns. 14 WORKING PROGRESS

15 OCEAN ENERGY: TOWARDS A STRATEGIC PERSPECTIVE SALINITY GRADIENT TECHNOLOGY OSMOTIC POWER: CONTRIBUTIONS AND CRITICAL ASPECTS State of art and critical aspects 25 MW plant requires 3,5 million m 2 of 7 w/m 2 power density membranes, m 3 /day of fresh water and an area of a football pitch. Biggest Reverse Osmosis (fresh water production) plant in Israel: m 3 /day, m 2 membrane area. Big players into place: Membrane and Pelton turbine suppliers and utilities (Statkraft). First pre-commercial plants (5-10MW) could be deployed in Need to prove technology and costs. Sites for Osmotic Power are in areas of low tides (small fresh and salt water mixing), low suspended sediment and bio-fouling rivers, nearby electrical connection. 15 WORKING PROGRESS

16 TIDAL CURRENT TECHNOLOGIES LEADING TECHNOLOGIES MCT Seagen 1,2MW device in Northern Ireland (2008) Installation of HS300 in Kvalsund (2003) AK-1000 at EMEC (2010) 500kW TGL at EMEC (2010) The first tidal current turbine at the Voith Hydro workshop in Heidenheim SR 250 installed at EMEC (2011) 6x30kW FreeFlow 5m installed in NY (2006) Clean Current (Alstom Hydro) turbine at Race Rocks (2006) Open Hydro 1MW turbine in Bay of Fundy (2010) ORPC 60kW Beta TGU tests at Cobscook Bay (2010) PS 100 in Humber Estuary (2009) Impresion of Minesto Deep-Gen 16

17 GLOBAL DISTRIBUTION OF TIDAL RANGE 17 tidal amplitude variations Source: The Role of Advanced Hydropower and Ocean Energy in Upcoming Energy Legislation, Washington, DC, 08 June 2007, George Hagerman Tidal current Source: Coordinated Action on Offshore Energy: Ocean Energy Conversion in Europe - Recent advancements and prospects, Centre for Renewable Energy Sources, Greece 2006

18 Tidal Commercial Projects Barrage de la Rance (240 MW) St. Malo, FRANCE Annapolis Royal (20 MW) Nova Scotia, CANADA KOREA Construction of three tidal barrages being planned; overall installed capacity reaching 2,000 MW; Completion of 254 MW Si-hwa tidal barrage expected in June

19 Tidal Current Sea Testing Northern Ireland 2007 Open Centre Turbine (250 kw) OpenHydro (Ireland) Installation at EMEC 2008 Seagen (1.2 MW) Marine Current Turbines Ltd (UK) First grid-connected commercial demonstrator 19

20 OCEAN ENERGY: TOWARDS A STRATEGIC PERSPECTIVE TIDAL CURRENT TECHNOLOGIES TIDAL ENERGY: CONTRIBUTIONS AND CRITICAL ASPECTS State of art and critical aspects More than 100 technologies, but few at an advance TRL level. Only 2 of them have installed and generated electricity at full scale, and 2 others coming soon. Technology seems to be converging, new technologies don t bring advantages over existing ones, fundamentals well understood from wind experience. wind type horizontal rotors leading the way. Big players into place: OEMs (Siemens, Alstom, Voith, Andritz, DCNS) and utilities (EDF, Iberdrola, RWE, E.ON, SSE, Statoil, Total, etc.). First pre-commercial arrays (5-10MW) being deployed in , and after that market could launch rapidly in UK, Canada, France. Funding of first pre-commercial arrays is restricted: UK leading the way, followed by Canada and France. 20 WORKING PROGRESS

21 Wave energy technologies 21

22 Wave Energy: several ideas under competition Oscilating Water Column (OWC) Overtopping devices Axi-simetric bodies heave motion Oscilating bodies (Submerged or semi-submerged) Rotational motion 22 Multiple parts Rotational motions between parts

23 POWER TAKE-OFF ALTERNATIVES Wave energy Air flow Water flow Relative motion between bodies Air turbine Water turbine Hydraulic pumps Hydraulic motors Mechanical transmission Mechanical gear Linear electrical generators F. Electrical generator or direct use 23

24 Wind waves and swells Waves generated by wind are called wind waves. When the waves propagate outside their region of generation, they are called swells. Where the water is deep, swells can travel very large distances, across oceans, almost without loss of energy. 24

25 HOW TO DESCRIBE A WAVE Wave direction Wavelength L Crest Amplitude A Trough Wave period T Frequency ω = 2π / T Wave height H 25

26 Propagation velocity (phase velocity) c T k From the boundary condition at the sea surface: h c tanh g c The velocity of propagation c depends on the wave period T (or frequency ω or f) and also on the water depth h. The sea is a dispersive medium for surface waves. The speed of sound in air is independent of frequency 26

27 27 Propagation velocity (phase velocity)

28 Limiting situations In deep water (in practice if h > λ/2) : tanh( kh) 1 c g k g gt 2 In shallow water (in practice if h << λ) tanh( kh) kh c gh c does not depend on T 28

29 Example 2 T 8 s g 9,8 m/s Deep water c gt 2 9, ,5 m/s ct 12, m Shallow water h = 1 m c gh 9,8 1 3,1 m/s ct 3,1 8 25,0 m/s Intermediate water depth h = 15 m h c tanh g c,785 0, c 0 tanh 9,8 c 2 T 2 0,785 rad/s 8 c 10,2 m/s ct 10,2 8 81,8 m 29

30 Propagation velocity (phase velocity) h (m) c (m/s) 1 3,10 24,8 3 5,25 42,0 5 6,63 53,0 10 8,86 70, ,22 81, ,09 88, ,65 93, ,00 96, ,33 98, ,44 99,5 (m) 12,48 99,8 30

31 Refraction effects due to bottom bathymetry The propagation velocity c decreases with decreasing depth h. As the waves propagate in decreasing depth, their crests tend to become parallel to the shoreline wave crests shoreline 31

32 crests rays shoreline Dispersion of energy at a bay. 32 Concentration of energy at a cape. shoreline

33 Real sea waves Significant wave height, Hs The real-sea wave height parameter is the significant wave height. It is traditionally defined as the average of the highest one third of the individual trough-to-crest heights H i (i=1,2,3, ), and is denoted by H 1/3. H 1/3 H j,1 H j,2 N / 3 H j, N /3 H 1 H 2 H 3 Time Mean water level 33

34 REAL SEA WAVES: AVERAGE ZERO UP- CROSS TIME T Z The individual zero up-cross time T i is the time interval between two consecutive instants where the wave elevation crosses the zero level in the upward direction. An average of these over a certain time provides a useful measure of the real-sea wave period. T1 T2 TN Tz N Time T 1 T 2 T 3 J.F. & 34

35 REAL SEA WAVES: A COMBINATION OF SINUSOIDAL WAVES Real sea waves contain a mixture of waves with different directions, frequencies and wave heights. J.F. & 35 Naval Oceanographic Office, USA

36 WAVE SPECTRUM A quantity derived from wave measurements is the so-called energy spectrum S(ω). It tells us how much energy is carried by the different frequency components in the real-sea mixture of waves. For a sinusoidal wave the average stored energy was given by 2 E g H /8 For a real sea wave we have instead E g 0 S( )d g H s 2 /16 36

37 Wave spectrum Example of power spectrum 0.2 S (m ( ) 2 s) S 1 A (rad/s) S d rms

38 Characterisation of the sea In deep water, the global power level (from all directions) of a sea state is given by: 38

39 A SCATTER DIAGRAM A scatter diagram is a tool for analyzing relationships between two variables. 39

40 Output power HOW PERFORMANCE CHANGES WITH THE WAVES The wider the curve the best The more centered with the dominant wave period on the site the best Depend on device type, geometry, size & control Wave period 40

41 Output power HOW PERFORMANCE CHANGES WITH THE WAVES The wider the curve the best The more centered with the dominant wave power density on the site the best Depend on device Power Take Off equipment and control Incoming wave power 41

42 42 PELAMIS POWER MATRIX

43 Exceedance probability Wave and Resource Statistics Power Exceedance Probability Lognormal distribution 43 WERATLAS Wave power (kw/m)

44 44 CONTACTOS