Seapower Platform

The ACER Project – Attenuator Cost of Energy Reduction

A large proportion of our engineering effort over the last few years has focused on this complex R&D project with Sea Power Ltd, developing their Seapower Platform wave energy convertor (WEC). 4cE led a consortium which applied for and won significant funding from Wave Energy Scotland, managing the contract throughout:

Stage 1: £300k over 12 months, one of 8 teams (out of 37 entrants) to secure funding;

Stage 2: £660k over 15 months, one of 4 teams who progressed from Stage 1.

The project was multi-disciplinary in nature, and can be considered as a collection of inter-related sub-projects, as detailed in the boxes below.


4cE’s involvement contributed to significant advances in bringing the technology forward towards commercialisation, including:

  • Robust 3rd-party-verified characterisation dataset of the device’s performance across a wide range of environmental conditions;
  • Development of a complex simulation model, validated by tank test campaigns, which is now a valuable tool for assessing performance and loading of different device configurations;
  • Concept engineering of the full-scale device, and investigation of different mechanical assemblies and construction methods;
  • Areas of uncertainty identified, failure mode (FMECA) analysis undertaken, and solutions developed to reduce technology risk;
  • Complex techno-economic model built up of the device in different locations, enabling robust assessment of the long-term Levelised Cost of Energy (LCOE);
  • Huge improvements in understanding the performance and costs drivers of the device, highlighting routes to reducing LCOE, and ultimately strengthening the future investment case for the Seapower Platform.

1. Project Management

4cE were responsible for:

  • Design of multi-disciplinary projects over 3 years, including test programmes;
  • Leading successful applications to secure funding;
  • Project management of all packages of work (as detailed in other boxes) including full control of cashflow, reporting, and delivery of milestone submissions;
  • Maintenance of technology and project risk registers, and chairing of design reviews;
  • Identification and engagement of new supply chain for novel components;
  • Management of subcontracts for specific packages of work.

2. Tank Testing

Tank testing campaigns at Kelvin Hydrodynamics Laboratory (KHL) and FloWave have been invaluable in understanding the behaviour of the device and its performance drivers, allowing validation of simulation models, and providing important data on performance and loading to be used in device design.

ACER 2 FloWave tank test composite
  • Design of experiments;
  • Model design and build, including bespoke 3D printed sensor housings;
  • Specification, integration and commissioning of instrumentation;
  • Design of Power Take-Off (PTO), data acquisistion system (DAQ) and user interfaces;
  • Test programme execution:
  • Stage 1 testing at KHL, University of Strathclyde: 1:25 model with linear dynamometer PTO;
  • Stage 2 testing at FloWave test facility, University of Edinburgh:
  • 1:50 survival model, with bending moment flexures and high-speed impulse sensors for slam load measurement;
  • 1:25 performance model with force-feedback geared servo PTO system;
  • Comprehensive data analysis of device performance, motions and loading.

3. Simulation & Modelling

The simulation model built up by 4cE provides an invaluable tool for evaluating the performance and characteristics of the WEC, allowing fast investigation into the effects of particular configuration changes far more cost-effectively than scale model testing alone.

Sea Power Numerical Modelling Banner 2
  • Full characterisation of device performance across a wide range of sea states, feeding into techno-economic modelling activities;

  • Optimisation of device geometry, including proving a key scaling theory specific to this WEC;
  • Investigation of the effects of different types of PTO damping on power capture and device motions;
  • Providing information about structural loads and mooring forces to feed into design calculations.

4. Concept Engineering & Front End Engineering Design

  • Device sizing and matching to site-specific wave resource;
  • System breakdown and subsystem identification;
  • Subsystem technology readiness assessment (DNV-RP-A203), to identify areas of high risk/uncertainty;
  • CAD model & system layout;
  • Focused work packages on key components (e.g. pontoon materials and construction methods) and interfaces (e.g. hinge bearings).
ACER 4 SP full scale concept
  • Supported Sea Power’s team on:
    • Structural design of chassis & pontoons;
    • Mooring design;
    • Marine operations and HSE planning.
  • Managed technology risk register and conducted failure modes amalysis (FMECA);
  • Chaired design reviews to ensure technology stage gates would be met.

5. Techno-Economic Modelling

4cE compiled a complex techno-economic model, drawing together data from a wide range of sources and calculating the predicted long-term Levelised Cost of Energy (LCOE). In a key innovation, device scale and length scale were kept as variables throughout the entire model, allowing these to be optimised for a specific site.

ACER 5 LCOE charts
  • Resource/sea state data from a variety of potential target sites;

  • Performance data from simulation work, validated against third-party-verified tank test data (fully scalable on device scale and length scale);
  • Structural engineering calculations for chassis and pontoon structures (fully scalable);
  • Cost data for materials, construction and marine operations, sourced from suppliers;
  • Variables for financial discounting, learning rates and bulk discounts.

6. Project Context

The ACER project has formed a key part of Sea Power’s development of the Seapower Platform, following on from several earlier tank test campaigns and open water tests:

In 2016, Sea Power successfully deployed their “5x” device – a large scale prototype of an earlier configuration of the device:

ACER 6 SPP 5x tow out collage

The ACER programme FEED work built on this experience to produce the design of the next large-scale ocean-going demonstrator, including significant advancements in:

  • Device optimisation for increased power capture;
  • Structural design optimisation for reduced cost;
  • Fully controllable rotary PTO system (as opposed to linear dynamometer on 5x device);
  • Updated mooring design and marine operations for deployment/recovery.
ACER 6 SPP 5x vs ACER3 render

It is planned that this demonstrator will also provide a test-bed for the testing of other marine energy technologies, including alternative PTOs, new pontoon materials/constructions, and novel mooring and electrical connectors.