“Our vision is to enable tidal energy be a significant part of the renewable energy mix. We want to have a tangible impact on global CO2 levels to slow the effects of climate change whilst having a positive impact on the diversity of marine life within our oceans”
Enabling Tidal Energy to Compete on Cost
QED Naval is a technology developer specialising in the marine renewable sector. Their tidal platform, Subhub, is a fully integrated system used to support tidal turbines and everything it needs to generate tidal energy including electrical infrastructure. Subhub brings about a step change in the cost of energy through innovation or a technology step. Further cost reduction can be brought about through learning by doing.
Achieving performance and reliability matrices of their technology and systems will prove cost reduction capabilities and show that tidal energy will become competitive with other forms of renewable energy. QED Naval has achieved the first stage of the proving the cost reduction at community scale. The next stage is a matter of scaling the technology with a few smaller technology steps for further optimisation and cost reduction.
Working with the Environment
One of the key design drivers for Subhub was to minimise the environmental impact of the platform. The best way to do that is to make it a seabed mounted system so it is invisible from the surface and maintains the seascape and navigation channels of shipping. It is beyond the diving depth of most birds. Advantageously, it means the extremes of wave loading are exponentially less than at the surface.
Subhub was chosen to be a gravity based foundation so an important part of its payload is its solid ballast. This simple functional part of the payload performs a very complex physical task of securing the platform on the seabed. It ensures that the platform has enough On-Bottom-Weight (OBW) to overcome the extreme wave and tidal forces in combination. QED Naval’s expertise allows them to characterise these complex forces and define this OBW. However, doing this means that Subhub has a very low environmental signature because there is no need for loud noise drilling systems which may displace marine life and contaminate the seabed with foreign material.
Importantly, Subhub has no other moorings to install so it allows a single offshore operation to install and retrieve the platform from and to the seabed. Having no other moorings means that the scouring of the seabed is minimised.
One of the main issues on the environmental impact is what happens to the platform and infrastructure at the end of the project’s life or decommissioning. In the case of Subhub everything is easily removed from the seabed by de-ballasting the system and removing the cabling. It can then be assessed for re-use or cut up and scrapped to realise the value in the steel so it can be recycled.