Data buoy

[This is our low-cost data buoy, a remote sensing platform project initiated during the project REDEMA Redesigning Madeira: Using Speculative Design to Rethink Energy Policy and Consumer Behaviour. The buoy currently measures sea state dynamics for ocean wave energy capture; next steps will extend the buoy as a remote sensing platform for a variety of Marine and Coastal Ecosystem Monitoring activities, and release a free and Open Source DIY kit for citizen science in EU Outermost Regions, Overseas Territories, and worldwide Small Island Developing States.]

Host Institution: ITI / LARSyS

Team: James Auger (PI) Julian Hanna (CO-PI), Max Willis (postdoc), Greta Adamo (postdoc), Victor Azevedo (engineer), Vitor Aguiar (engineer)

Test of Version 3, with LoRa wireless communication (above).

This project has grown from original Speculative Designs for ocean wave energy collection devices, published in the Journal of Futures Studies https://jfsdigital.org/towards-sustainable-island-futures-design-for-ocean-wave-energy/

The initial designs were imaginaries, these do not physically exist, but serve to focus attention on possible future alternatives to designing renewable energy systems, and elaborate issues in the domain under investigation, the coastal zone of isolated islands like Maderia. Three such future objects were outlined: the PowerBreaker, a reimagined tetrapod that could collect energy, the Blue Beast, a somewhat more realistic portable energy collector that was attached to the breakwater, and PowerCrabs, a futuristic concept for semi-autonomous networked energy collectors that would live among the tetrapods, collecting energy and transforming it to electricity.

PowerBreaker
Speculative Design for breakwater wave energy collectors in the form of tetrapods
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The Journal of Futures Studies article also elaborated three distinct applications of the future to design: Extrapolation, which used data and trends from the present to imagine possible futures, Reflecting on the Present, in which an imaginary potential future forces introspection on conditions we are experiencing now, and Backcasting, which imagines a preferable future state, and works back in time to the present, asking what steps would need to be taken to arrive there.

The low-cost data buoy is a product of Backcasting, for in order to implement any of our designs for wave energy collection in the coastal zone, we need first to be able to monitor and understand the wave dynamics of the coastal zone. To support community ownership of the data and encourage local community-scale renewable energy projects, any data collection system must be affordable. To this effect, we make what is known as a Material Speculation, that is a semi-functional, or in this case, a fully functional physical prototype that facilitates transition to that preferable version of the future.

We started with site selection, and the Maritime Spatial Planning maps of the region, and reconnoitred by land and sea, and googlemaps to find an appropriate spot, at Ponte do Lazareto. Then through our contacts on the island at the Oceanographic Observatory of Madeira (OOM) and Institute of Forestry and Conservation of Nature (IFCN) got a permit for a year’s investigations at Garajau Marine Protected Area (4/2020 H). Then we hired a drone operator to survey the site (another permit) and made a detailed map of the site, by hand, which we geo-referenced using a handheld GPS, and layers in free open source program QGIS. We printed the map, laminated it, and then took depth measurements in the particular areas we want to run our tests.

Back in the lab, we began both physical component and systems design. The buoy form is a repurposed life ring, with aluminium slats that support a PVC pipe. PCB’s are designed, then laser etched onto copper coated boards, which are then washed in acid to reveal the final power and control boards. In the first version, the platform included an Arduino, acelerometer, gyroscope, magnetic compas, dedicated clock, and card data logger. Waterproofing was an issue, and we lost one prototype on the first test, but not before it recorded 36 hours of data. The second version had solar power, and a sleep cycle: it recorded 10 minutes of data, then slept for 50minutes, and in this way it lasted more than a week. When we retrieved it from the sea, the battery was still charged, which is a good sign. The third version is now in development, and uses LoRa low frequency radio communications, so the buoy does not need to be retrieved form the sea to access the data, stored on the card.

Before deploying, we had to place concrete buoy moorings in the sea at the test site. After determining and marking on the map the most suitable places, over several dives we ferried the concrete bases into place, and installed marker buoys. Before a big storm that came from the south, we added 50Kg or so of heavy chain to the outermost buoy. To deploy, we swim out with the buoy and replace the marker buoy with the data buoy. On one occasion when we returned to the test site, the seas were too wild, and we deemed it too dangerous to retrieve the buoy, and returned a few days later. With the version 3 buoy, which will have radio communications, we anticipate not needing to retrieve the buoy for extended periods…as long as everything stays waterproof!! The buoy can power with solar during the day and charge its battery, which has enough energy to continue monitoring the waves overnight, and for a few cloudy days, until the solar is strong enough again to power the batteries. As we move to more intensive calculations on the platform, and radio transmissions, we may need to add battery capacity, and perhaps also another solar panel, however the objective is to keep the buoy low cost.

The data buoy was initially developed for measuring wave dynamics (significant wave height, wave period and direction) however the platform was designed to be able to add other sensor payloads. Currently we are in testing the buoy for Water Quality monitoring, with sensors for for Sea Surface Temperature, salinity, Ph, and Dissolved Oxygen. This opens up a wide range of applications for the low-cost data buoy, for example for aquaculture management, Environmental Impact Assessment and habitat studies that connect aquatic life with ocean chemistry.

Our initial Water Quality monitoring testing used a new form, a drag buoy. This enables the sensor payload to be taken along transects, or tracks, and maps GPS coordinates to the ocean chemistry readings. For example in our test zone, we began towing the buoy at the westernmost part of the Garajau Marine Protected Area where the beach receives strongly focussed waves, and the water is murky and roiling. From there we moved around the front of the prominatory, and to the east, where a small cave concentrates the wave actions, and numerous freshwater streams empty from the rocks above into the sea. Along the tracks we are able to see changes in salinity and dissolved oxygen, relative to visual disturbances underwater where the freshwater mixes with the sea, and in the open sea, where temperatures were a bit higher at the surface. These are only preliminary measurements, but it gave clear results, the GPS was surprisingly accurate, and the entire system, sending data to the shore and our institute servers worked flawlessly. An excellent initial result!!