(Updated 16.03.2020: added mast, camera, number of devices and additional data line) Solar power and an undersea habitat does not seem to fit each other. But in 2012 I had the idea of a device that opens its harvesters only if the conditions are appropriate just like a hibiscus blossom at dawn. I called it a Solar Lily.
A bionic shape for harvesting solar energy
Our Solar Lily is folded together on the bottom of the sea. In its center is a buoy surrounded by solar panels. The whole set is held on the seafloor with a reinforced cable ending in a winch that is mounted on a block of ballast. When the sun is up, the waves low and the wind weak it’s time to wake up. The winch releases the cable and the Solar Lily starts to rise (lifted by the center buoy). Small buoys on the end of each solar panel are reaching surface first and make the panel tips drift away from the center, while the buoy is still under water and rising. When the buoy reaches surface the panels lay flat on the water, move gently with the waves and immediately start to generate energy that is transmitted to the habitat by the cable.
If one of the alert conditions appear, the winch starts to drag the buoy down again. The swimmers on the ends of the panels approach the center and folding around it while the buoy is lowered .
On the seafloor the Solar Lily then waits for its next assignment. There it will not be exposed to the forces of waves and winds. Currents will make it lean like kelp, while the surfaces of the solar panels are secured by being folded with their faces to the center, where they protect each other.
To be discussed
The possible size of the panels has still to be discussed as well as the ideal shape of the ‘flower’: do the corners have to be empty or is there a way to design them in a folding triangle shape similar to Origami.
How much loss of energy will appear while transporting energy from the panel to the winch and from there to the storage bank inside the habitat. To calculate the necessary length of the cable we have to sum up the following parameters:
- Depth (surface to seafloor)
- The amplitudes of tides and waves.
- Drift Scope (might also result from step 2)
- Safety Distance (winch to habitat)
- Handling Bonus inside the Habitat
A depth of 20 m might end up in a cable length of 60 m after all. Maybe the loss of energy is that high that it rules out the whole concept for being not effective enough for example if the winch uses all the energy that the Solar Lily is producing. That would truly be self-sufficient 🙁
How many Solar Lilies do we need? If the panel size is not enough we can increase the number of lilies around the habitat.
How can we store the energy inside the habitat? How can we maintain the winches, when they are exposed to salt water 24/7? Would the angle of the solar panels on the surface towards the sun be appropriate? And is the whole system feasible at all compared to other alternatives or at least in combination with other solutions?
Can we use waste air from the habitat to fill the buoy on the seafloor to ascend, while releasing the air on the surface would let it sink again in order to save energy from the winch?
Controlling the Solar Lily
If all these questions lead to a positive end result we can finally think of implementing the set to the IT system, that measures the alert conditions and decides by itself if and when the Solar Lilies are risen or lowered. Again: the conditions would be a) time of the day, b) wave height, c) wind speed, d) are the winches clear of personnel, e) are there reported damages on the equipment, f) is the emergence area clear (boats, swimmers, drift items). If these conditions allow operation of the winches the IT system would be free to decide whether operating or not. Maybe a request of confirmation should be considered.
- a mast in the middle of the buoy with a camera to monitor the devices condition on the surface. There has to be an additional data line to the surface next to the holding cable.
- additional GSM receiver to support/backup telemetry or telecommunication
- a weather station to measure environmental conditions.
- mirror reflectors would not only mark the lilies position but also the station’s
Image credits: Oregon Department of Transportation / CC BY (https://creativecommons.org/licenses/by/2.0), available on Wikimedia Commons