Wave Energy Converter (WEC) Power Simulator

Compare the four main families of wave energy converters — Oscillating Water Column, point absorber, attenuator and overtopping — for a given wave climate. Set the significant wave height, peak period, device width and PTO efficiency to see the wave power density, capture width ratio, annual energy production and rough LCOE update in real time.

Parameters

WEC Type

Representative CWR and natural period are set automatically

Significant wave height H_s

Peak period T_p

Water depth d

Deep-water theory applies roughly when d ≥ λ/2

Device width W

PTO efficiency η

Overall PowerTakeOff efficiency (hydraulic, air turbine or direct drive)

Results

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Wave power density (kW/m)

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Capture width ratio CWR

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Absorbed power (kW)

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Electrical output (kW)

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Annual energy (MWh/y)

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Rough LCOE (USD/MWh)

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WEC motion — wave–device coupling

The sea surface (blue) drives the device, which transfers energy through the PTO to the generator (yellow). The animation switches according to the selected family: OWC, point absorber, attenuator or overtopping.

Electrical output vs significant wave height

CWR comparison across WEC families

Theory & Key Formulas

$$P = \frac{\rho g^{2}}{64\pi}\,H_{s}^{2}\,T_{p}, \qquad P_{\text{capture}} = P \cdot W \cdot \text{CWR}$$

Deep-water wave power per unit crest length P [W/m] (ρ = sea water density 1025, g = 9.81, H_s = significant wave height, T_p = peak period) and absorbed power P_capture [W] from device width W and capture width ratio CWR.

$$P_{\text{elec}} = P_{\text{capture}} \cdot \eta_{\text{PTO}} \cdot f_{\text{tune}}, \qquad f_{\text{tune}} = \max\!\left(0.3,\; 1 - \frac{|T_p - T_{\text{nat}}|}{15}\right)$$

Electrical output P_elec includes the PTO efficiency and a resonance-tuning factor f_tune that approaches 1 when the peak period matches the device's natural period.

$$\text{AEP} = P_{\text{elec}} \cdot 8760 \cdot \text{CF}, \qquad \text{LCOE} = \frac{C_{\text{kW}} \cdot P_{\text{rated}} \cdot 0.08}{\text{AEP}}$$

Annual energy production AEP [MWh/y] (capacity factor CF ≈ 0.30) and rough LCOE [USD/MWh], where C_kW is the per-kW CAPEX and P_rated is taken as 2 × P_elec for typical sizing.

Wave Energy Converters — Oscillating Water Column, Point Absorber, Attenuator

🙋

Wave energy means making electricity from ocean waves, right? It doesn't get talked about as much as solar or wind — why hasn't it scaled up yet?

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Good question. The resource itself is huge: an energetic North Atlantic site averages 50–100 kW per metre of crest length, which is roughly fifty mid-size houses' worth of electricity per metre of coastline. Three things hold it back: (1) the structures have to survive brutal storms, which is expensive, (2) there is no design convergence yet — wind has settled on the three-bladed HAWT, but WEC still has four competing families (OWC, point absorber, attenuator, overtopping), and (3) running subsea cables from offshore back to the grid is costly. The industry is still in the commercialisation race.

🙋

What are those four families actually doing? The animation on the right changes when I switch the select on the left.

🎓

In broad strokes: an OWC builds an air chamber inside a breakwater so the waves push an air column up and down, driving an air turbine (typically a Wells turbine) on top — LIMPET (500 kW, Scotland) and Mutriku (296 kW, Spain) are the textbook examples. A point absorber is a surface buoy whose heave is bled off through a hydraulic ram — OPT's PowerBuoy is the famous one. An attenuator is the snake-shaped Pelamis: long pontoons hinged together so the wave bends them and hydraulic cylinders soak up the bending. Overtopping (Wave Dragon, Denmark) is a ramp that lets waves slosh into a reservoir, then runs the trapped water back to sea through a low-head turbine.

🙋

What about that CWR number — it shows 0.40 for OWC. What does that mean?

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Capture Width Ratio. It's the absorbed power divided by (wave power × device width), so it's a dimensionless efficiency. The theoretical ceiling is 1.0, and in real life OWC hits 0.30–0.45, point absorbers 0.25–0.40, attenuators 0.30–0.50, overtopping 0.20–0.35. The simulator also applies a resonance-tuning factor f_tune: when the peak period is close to the device's natural period, f_tune approaches 1. OWC is designed around 9 s, so T_p = 9 s gives f_tune = 1.0 exactly; Pelamis being long resonates near 11 s.

🙋

The LCOE comes out at about 305 USD/MWh. Is that a lot?

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It's high. Offshore wind is 70–100 USD/MWh, utility-scale solar 30–60, so wave is three to five times more expensive today — and that is the main commercial hurdle. The path down is well-known: drive CAPEX from 5,000 USD/kW toward 2,000 USD/kW via volume manufacturing, push the capacity factor from 30% toward 40%, and extend asset life from 20 to 30 years. EU H2020 OceanERA, the US DOE Marine Energy Lab and EMEC (European Marine Energy Centre, Scotland) are running the demonstrators that feed back the data. Realistic optimism puts wave LCOE near 150 USD/MWh by the mid-2030s; matching offshore wind will still take longer.

Frequently asked questions

For deep-water waves the power per unit crest length is P = ρg²/(64π)·H_s²·T_p, with ρ=1025 kg/m³ (sea water), g=9.81 m/s², H_s the significant wave height [m] and T_p the peak period [s]. For H_s=2.5 m and T_p=9 s this gives P ≈ 27.6 kW/m. Energetic North Atlantic sites can reach 50-100 kW/m on an annual mean. Japanese Pacific coasts see roughly 6-12 kW/m and the Sea of Japan side 4-8 kW/m.

The Capture Width Ratio is the absorbed power divided by (wave power × device width). It is a dimensionless device-efficiency metric whose theoretical maximum is 1.0. Real devices reach about 0.30-0.45 for OWC, 0.25-0.40 for point absorbers, 0.30-0.50 for attenuators and 0.20-0.35 for overtopping converters. This simulator multiplies a representative CWR by a resonance-tuning factor that grows when the peak period approaches the natural period of the chosen device.

Wave energy's Levelized Cost of Energy is currently in the 200-500 USD/MWh range, well above offshore wind (70-100 USD/MWh) and solar PV (30-60 USD/MWh). Typical CAPEX is 4,500-6,000 USD/kW, capacity factor 25-35% and asset life 20-25 years. The three main cost drivers are (1) survivability against extreme sea states, (2) mooring and subsea-cable infrastructure and (3) lack of design convergence. The tool estimates LCOE as ratedPower × CAPEX × 0.08 / AEP.

OWC: LIMPET on Islay, Scotland (500 kW) and Mutriku in Spain (296 kW, the first commercial OWC breakwater). Point absorbers: OPT's PowerBuoy (~150 kW) and Carnegie Clean Energy's CETO. Attenuators: Pelamis (750 kW, hinged snake-like device tested at EMEC Scotland). Overtopping: Denmark's Wave Dragon (4-11 MW prototypes). Today's commercial scale is 0.1-1 MW per unit, with multi-device farms used to reach MW-scale output.

Real-world applications

Diesel replacement for remote islands: Off-grid islands often pay 400-600 USD/MWh for diesel generation, which makes wave at 300 USD/MWh competitive even today. Hawaii, the Scottish islands and southern Chile are the most cited candidate markets.

Breakwater-integrated OWC: Building the air chamber into a harbour breakwater lets some of the structural cost be amortised against the port-engineering budget. Mutriku in Spain (296 kW, 16 turbines) is the first commercial OWC breakwater and has operated for over 13 years, generating roughly 600 MWh per year. The Japanese MLIT is exploring the same approach.

Stand-alone offshore power: Small (100 W – 10 kW class) point absorbers are useful for autonomous oceanographic buoys, offshore aquaculture, seabed-survey hubs and naval sonar stations. The PMEC test site in Oregon (US) and EMEC in Orkney (UK) run these as commercial demonstrators.

Offshore hydrogen production: Pairing WEC farms with seawater electrolysis to ship hydrogen ashore is being studied by EU's Atlantic Hydrogen initiative. Liquid fuels travel long distances better than electricity and reduce conflicts with established fisheries.

Common misconceptions and pitfalls

The biggest misconception is that "the wave resource is huge, so the electricity will be cheap". Resource availability and device cost are independent problems. Even at a 50 kW/m site a 30 m wide device only intercepts up to 1.5 MW, and at 5,000 USD/kW CAPEX that is roughly 7.5 M USD upfront — still more expensive per kW than a 3 MW onshore wind turbine. Treat resource and economics as separate questions.

Another trap is assuming "bigger devices always win". Doubling the device width W only doubles absorbed power (CWR is preserved), while structural cost typically scales with W², so unit cost per kW does not necessarily fall. The "bigger is cheaper" story of wind turbines does not carry over cleanly to WECs — many developers now prefer farms of medium-size units sharing operating costs.

Finally, this tool is a rough estimator. Serious WEC design needs (1) coupled hydrodynamic-structural simulations (OpenFOAM, STAR-CCM+, WEC-Sim in the time domain), (2) energy production over irregular wave spectra (JONSWAP, Pierson-Moskowitz), (3) survivability checks against the 100-year wave, and (4) mooring design with fatigue assessment. Use the simulator for concept-level comparison and sensitivity analysis, not as a substitute for project-grade analysis.

Wave Energy Converter (WEC) Power Simulator

Wave Energy Converters — Oscillating Water Column, Point Absorber, Attenuator

Frequently asked questions

Real-world applications

Common misconceptions and pitfalls

How to Use

Worked Example

Practical Notes