How does your sinking machine work?
Our system is actually pretty simple, which is the great thing about it. Simple works! Our approach is both a sensible one designed to collect Sargassum as quickly as possible, and also one that is future proof to allow us to scale quickly in the future.
Initially, we will use a surface based vessel that will carry 2 collection systems - or AlgaRays as we call them. Their design has been inspired by the Manta Ray.
Travelling through the water at a speed of approximately 3knts, once full, the forward AlgaRay will drop down beyond 135m whilst the rear AlgaRay takes over collection. This way we can continually harvest whilst dropping seaweed at the same time. Below 135m depth the Sargassum becomes negatively buoyant and will sink when released, never to be seen again! The really great thing about our method of CDR is that the system is extremely energy efficient. We only have to move material to the right depth and that’s it. Without any phase changes or intensive processing, or moving the seaweed out of the water. Crucially the AlgaRay isn’t impacted by constant changes of pressure: it’s an open structure, so there’s no need for complicated and expensive pressure resistant submarine-like engineering.
The AlgaRays are hydrodynamically shaped to cut through the water despite their size. Once at the right depth, the ray will release its cargo of Sargassum, where water pressure has crushed the hundreds and thousands of air sacs attached to them, making it negatively buoyant. There’s a trade off between going deeper and the associated speed and spread of sinking: it takes more time and energy to go deeper, but the modelling suggests the seaweed will sink faster the deeper it is released and spread out over a smaller area. We’re already working out what’s the best approach in our early trials. As the Sargassum falls away to the sea floor, the empty AlgaRay returns to the surface ready to start collecting again. The whole sequence is captured on video and recorded with a blockchain.
While the surface based vehicle will get us started nicely, we are already developing the large-scale underwater glide version of the AlgaRay that will carry out the same task but with additional capabilities. A bit like the tethered surface system we are starting with in design, it will ultimately become fully autonomous. It will allow us to continue to operate irrespective of adverse weather which can be experienced in the area.
All our vessels will be carbon neutral operating solely on electric propulsion via onboard lithium batteries and PV panels.
Initial deployments will utilise semi-autonomous systems with operators in close proximity on an electric support vessel. We have to be aware that we are not the only operators in the sea, hence the human operator just to keep an eye on things. As autonomous technology matures, we will be upgrading the vessels in line with this, and the architecture of the vessels is designed to facilitate this maturing of technology without significant changes required.