BALANCING
THE GRID
WITH ONE
MACHINE
One machine. One PTO. Two complementary energy functions.
Generate when the grid needs power. Store when it needs flexibility.
GENERATION MATTERS.
FLEXIBILITY IS KEY.
As renewables grow, the challenge is not only how much clean energy we can generate. It also matters how the system responds when energy is available and when it is needed.
THE QUESTION IS NO LONGER JUST HOW MUCH ENERGY WE CAN GENERATE.
It also matters whether we can generate, absorb, store or release energy when the system actually needs it.
When the grid needs power
Generate: deliver useful energy to the system.
When energy is available to store
Absorb and retain energy to release it when it is more useful.
TWO COMPLEMENTARY FUNCTIONS.
ONE SHARED NEED: BALANCING THE SYSTEM.
A SINGLE ASSET REPLACING TWO INVESTMENTS
To generate and store energy, a conventional solution requires investment in specialised assets. ESWave brings both functions together in one machine and a single PTO, which changes function according to the system's needs.
Two specialised investments
One asset to generate and another to store, each with its own project, grid connection licence, equipment, operation and maintenance.
One asset with complementary functions
ESWave shares the machine and PTO between generation and storage. The TWEFDA Association integrates these functions and their management into a single project, conceived as an ad hoc solution.
Integration from the design stage reduces the work of coupling independent technologies and developing an additional control layer to coordinate them. Generation, storage and their management form part of the same solution.
The support structure, connection and other project elements remain part of the investment. Savings depend on the configuration and must be assessed for each project.
Installation, maintenance and protection.
A machine designed to arrive afloat, connect to its support and return to shore. Mobility is part of how ESWave is installed, maintained and protected.
Major maintenance can be carried out onshore.
When a major intervention requires it, ESWave can be disconnected and towed to port. After the work, the machine can return to its location.
Protection in place. Shelter when needed.
Two complementary responses: raise and ballast the machine at its location, or remove it preventively before an extreme event.
Raise and ballast.
The design envisages raising ESWave approximately 15 metres above the ocean surface and ballasting it with seawater to increase its stability.
Anticipate and seek shelter.
Buoy data, satellite information and weather forecasts can support the decision to disconnect exposed ESWaves and tow them to a safe location.
A harbour of refuge would allow units to remain sheltered during the extreme event and support their subsequent return.
Design strategy. Survival limits and disconnection and towing windows require validation for each configuration and location.
Moving the machine also changes where it can be useful.
Redistribute units.
The ability to exchange ESWaves between locations allows the arrangement of assets to adapt to production and maintenance needs.
Bring energy to a prepared location.
A prepared location with a jacket and a connection to a portable hub could receive a towed ESWave to supply marine electricity during reconstruction after an earthquake, provided the infrastructure remains usable.
WHAT IF A SINGLE ASSET COULD CHANGE FUNCTION?
Instead of two specialised machines, ESWave proposes a flexible physical platform that changes its role according to what the energy system needs.
ONE MACHINE.
ONE PTO.
TWO ENERGY FUNCTIONS.
Not just hybrid energy: hybrid functionality. The same machine and a single Power Take-Off, or PTO, allow it to alternate between generation and storage.
Generate
Deliver energy when generation is the useful function for the system.
Store
Receive available energy, retain it and allow its later release.
TWEFDA proposes the term Hybrid Functionality Energy Device (HFED) to describe this architecture. The main function changes; the asset remains the same.
WHAT GOES UP DIFFERS FROM WHAT GOES DOWN.
TWEFDA explores an energy conversion mechanism, within known physical laws, in which the converter behaves differently during ascent and descent.
On the way up
The system adopts a lower-weight state.
On the way down
The system adopts a higher-weight state.
Weight-Changing Energy is at the computational proof-of-concept stage. Preliminary simulations indicate potential to improve capture compared with a fixed-weight configuration. Physical validation is the next decisive step.
An improvement of this kind could contribute to the commercial viability of wave energy. Detailed technical information is provided through controlled access, subject to an NDA and the applicable permissions.
WaveAmp opens the first European commercial route for WCE.
FOUR APPLICATIONS.
ONE PIECE OF HARDWARE.
One ESWave and a single PTO provide a common physical platform for four renewable energy applications.
Wave energy
Generation from relative motion between the sea surface and a fixed reference.
Weight-Changing Energy
Non-reciprocal energy conversion through changes of state between ascent and descent; pending physical validation.
Offshore Pumped Hydro
Mechanical energy storage as gravitational potential in the ocean.
Tidal Range Energy
Energy release coordinated with changes in tidal level.
CAPACITY DOES NOT CREATE FLEXIBILITY BY ITSELF.
CONTROL DOES.
The control architecture determines what to do, when to do it and how to change the asset's function according to available energy and the system's needs.
FROM MARINE ASSET TO ENERGY NODE.
The TWEFDA Hub provides a common offshore connection point between generators, storage, consumers and energy pathways.
Connect close to the asset
A common offshore point can change where each asset connects to the wider energy system.
Integrate and direct flows
The Hub configuration allows generation, storage and consumers to connect, as well as other networks or hubs.
Available connections and functions depend on the project configuration and existing infrastructure.
SIX ESWAVES.
DIFFERENT FUNCTIONS.
ONE COORDINATED SYSTEM.
A TWEFDA Association brings together six coordinated ESWaves. Each unit can change function independently: some generate while others absorb or retain energy.
Coordination allows functions to be distributed between units according to system conditions. Management is integrated from the design stage: the Association is conceived as an ad hoc solution within a single project.
ONE ESWAVE CAN GENERATE OR STORE.
AN ASSOCIATION CAN GENERATE AND STORE.
At the same time, through units performing different functions.
THE GRID DECIDES WHAT THE MACHINE DOES.
Balancing is no longer solely a problem for the grid to solve: the asset is designed to contribute to the system's response.
POWER NEEDED → GENERATE
CONDITIONS CHANGE → CHANGE MODE
A single PTO changes function according to conditions. Commercial provision of grid services requires the corresponding configuration, validation and contracts.
TIME BECOMES AN ENERGY RESOURCE.
The value of energy depends on how much we have and when it is available. Being able to store it and release it at another time adds a new dimension to its management.
The economic outcome depends on prices, losses, costs and the project's operating conditions.
LCOCEOS.
VALUING A MACHINE THAT GENERATES OR STORES.
Conventional metrics allow generation and storage to be analysed separately. ESWave shares its machine, PTO and some costs between both functions. Evaluating it requires considering that architecture and how it uses its time.
Levelised Cost Of Combined Energy Or Storage. TWEFDA proposes LCOCEOS as a framework for a joint assessment of an asset with complementary functions.
| Metric | What it analyses | What it contributes to this assessment |
|---|---|---|
| LCOE | The levelised cost of generating electricity over the project's lifetime. | Helps analyse generation. The storage function and shared costs require explicit treatment. |
| LCOS | The levelised cost of storage relative to the energy it delivers. | Helps analyse storage and discharge. Previously charged energy is not new generation. |
| LCOCEOS | TWEFDA's proposal to jointly evaluate generation OR storage in a shared asset. | Proposes considering common costs, choice of function and allocation of operating time. |
One machine. Different uses of its time.
- GENERATECapture wave energy.
- STOREAbsorb and retain energy.
- RELEASEReturn previously stored energy.
- WAITRemain locked until release.
Calculating a value requires defining lifetime, system boundaries, shared and specific costs, charging energy, losses and operating profile. LCOCEOS is a TWEFDA proposal; the original article does not establish a closed formula or a calculated value. It is not obtained by adding LCOE and LCOS.
MORE FUNCTIONS.
ONE OFFSHORE SYSTEM.
Generation, storage, grid support and infrastructure can become complementary parts of the same offshore system.
Generation
Deliver energy when generation is useful.
Storage
Absorb available energy and retain it for later.
Grid support
Adapt the asset's function to system conditions.
Infrastructure
Connect assets, consumers and energy pathways.
WHAT IF AN ASSET AT THE END OF ITS LIFE COULD BE THE START OF A NEW ENERGY SYSTEM?
Existing infrastructure can offer new possibilities where reuse is technically, economically and regulatorily viable.
Reuse
Retain structures that can still be useful.
Repurpose
Give offshore locations a new energy role.
Reconnect
Turn infrastructure into an interface for new energy flows.
Extending the useful life of selected structures can preserve options for new technologies. Reuse depends on each location and does not remove applicable decommissioning obligations.
FROM ONE MACHINE TO A PLATFORM.
FROM A TECHNOLOGY TO A COMMERCIALISATION PATHWAY.
The story that began with one word — BALANCE — now connects machines, functions, coordinated systems and maritime infrastructure.
TWEFDA and WaveAmp
TWEFDA retains global ownership of the technology and intellectual property platform. WaveAmp is the European commercial route for Weight-Changing Energy, through a licence limited by field of application.
Technology platform and intellectual property.
European commercial route for WCE.
The human story
TWEFDA began by asking whether problems, waste and infrastructure at the end of its life could become resources. That idea continues to connect the technology with future generations.
THE OFFSHORE ENERGY SYSTEM CAN DO MORE.
Generate when energy is needed. Store when it is available. Connect assets. Give existing infrastructure a new purpose.