Tide Energy Technologies San Jose State University FX Rongère April 2009

Tidal Dams

Tidal Dam The dam creates a difference of potential energy between the tide pond and the open sea ΔzΔz

Power Generation Incompressible fluid: For the chosen control volume, the system is in steady state, then:  

z1z1 z2z2 Power Generation

With: τ : tidal period η : Turbine conversion rate A T : Area of the turbine R : Range of the tide A pool : Area of the tidal pool

Basin Management To optimize power generation the flow gates are kept closed some time after high and low tides

If Δz is constant

La Rance Tidal Power Plant Tide mean range: 8.4m Tide basin area: 22 km 2 10 m 9 m 8 m 7m 6m 5m 4m 3m

La Rance Tidal Power Plant 24 Units of 10 MW each built between 1961 and m dam 480 GWh/y CF=23%

Model of La Rance Tidal Power Plant

The Severn Barrage (UK) Capacity: 8,640 MW, 17 TWh, CF= 23%, Length=15.9 km

In the Bristol Channel Range 8.2 m, Basin Area: 480 km 2 The Severn Barrage (UK)

Economics The Severn Barrage (UK)

Current Turbines

Power Curve Similar to a wind turbine Source: Source: George Hagerman Tidal Stream Energy in the Bay of Fundy, Energy Research & Development Forum 2006 Antigonish, Nova Scotia 25 May 2006

Generation prediction Combining Power curves and current data, we can calculate the generated power

Turbine main components Rotor Extracts power from flow Turns at low RPM rpm Conversion rate varies with flow velocity (45% max) Gearbox Increase rotational speed of shaft from turbine 80-95% efficient Foundation Secure turbine to seabed Resist drag on support structure and thrust on rotor Generator and Power Conditioning Generate electricity Condition electricity for grid interconnection Turns at high RPM 95-98% efficient Source: Brian Polagye Tidal In-Stream Energy Overview March 6, 2007 General concept is similar to wind turbines

Turbines η is the conversion rate of the turbine, typically 25% to 35% 300 kW, 6 m prototype developed by Marine Current Technologies in operation in the Bristol Channel since MW, 20m twin rotor prototype currently developed by Marine Current Technologies installed in Northern Ireland’s Strangford Lough (2008) Marine Current Technologies

Strangford Lough project Installed in April 2008

Turbines Verdant Power 35 kW, 5m Diameter turbine developed by Verdant. Prototype installed in New York at Roosevelt Island ( ). Project of 175 kW

Results 7,000 hours of operation Electricity generation Rotor damage No fish collision

Turbines Lunar Energy 2 MW, 21m 7 blade rotor prototype currently in development Gravity Foundation: concrete slab Power augmentation by convergent-divergent ducting to increase conversion rate Promising since On the 11th March 2008 Lunar Energy signed a Memorandum of Understanding with Hyundai Samho Heavy Industries (HSHI) and Korean Midland Power (KOMIPO) to develop the 1MW RTT unit for deployment into Korean coastal waters

Turbines Clean Current Pile Mounted 4 bladed, 14 m, 1 MW A 65 kW prototype has been Tested at Race Rocks from Sep 2006 to May 2007 Race Rock is a marine reserve run by Lester B.Pearson College on Vancouver Island (Canada)

Clean Current Turbine

Turbines Open Hydro Open Center Rotor Diameter 15 m rated at 1.5 MW Operating Conditions: Current speed > 0.7 m/s Prototype under test at European Marine Energy Center (UK) – Dec April 2009: Contract with Snohomish County Public Utility District (SnoPUD), to develop a tidal energy project in the Admiralty Inlet region of the Puget Sound

Turbines Gorlov Different mounting Prototype has been tested at Uldomok Strait in Korea in m diameter and 2.5 m high 1.5 kW

Turbines Enemar Kobold Moored – surface mounted 3 vertical articulating blades vertical: 5.0 m diameter: 6 m chord: 0.4 m m/s Prototype has been deployed in Straits of Messina 4 years operational experience

Turbines Barry Davis’ vertical axis turbine Source:

Turbines Blue Energy Project Philippine Dalupiri 2200 MW Blue Energy Project

Turbines The Energy Business Limited

Foundation Technologies Monopile Small footprint Established technology used in offshore wind Gravity Base Chain AnchorsTension Leg Hollow steel pile driven or drilled into seabed Pros: High cost in deep water Installation expensive for some types of seabed Cons: Heavy foundation of concrete and low cost aggregate placed on seabed Deep water installation feasible Pros: Large footprint Scour problems for some types of seabed Decommissioning problems Cons: Small footprint Deep water installation feasible Chains anchored to seabed and turbine Pros: Problematic in practice Device must have high natural buoyancy Cons: Submerged platform held in place by anchored cables under high tension Small footprint Deep water installation feasible Pros: Immature technology now being considered for offshore wind in deep water Cons: (10-40m) Source: Brian Polagye Tidal In-Stream Energy Overview March 6, 2007

Projects Worldwide

Gulf Stream Current

Florida Current Resource

Current speed (knots)

Companies to follow Blue Energy Canada Clean Current Technology Marine Current Turbines GCK (Gorlov) Lunar Energy Open Hydro Enemar Kobold Verdant Power Seapower Tidal Electric Aquantis Annapolis Tidal Generating Station (USA)