article / 12 July 2023

Sustained Effort: Can We Improve the Sustainability of Marine Telemetry Tags?

In this article from Alasdair Davies, he discusses how marine tracking's unique challenges could impact its potential for sustainability in the future.

While all environments present unique challenges to conservation technology, be it humidity, bugs, curious wildlife, thick canopy covers, and much more, marine technology may take the prize for the most challenges to consider during the design process. In this article from Alasdair Davies, you'll learn about how these challenges are shaping sustainability efforts for those building and using marine conservation tech.

Can We Improve the Sustainability of Marine Telemetry Tags?

By Alasdair Davies

I can never help but wonder just what lies in wait for each and every biologger, telemetry tag, or instrument released into the depths of the ocean. 

Inside each protective enclosure (often just a few millimetres thick) are delicate electronics, circuitry, and batteries, all of which need to be protected from the harsh saltwater environment, will often need to survive great depths and crushing pressure, and will need to operate for years upon end. Most will never be seen again, attached to the carapace of sea turtles, clamped to dorsal fins of cetaceans, or left to drift on the surface and survive through storms and swells. 

There’s a classic saying: “hardware is hard.” It’s true, there’s considerable engineering experience needed to design and develop solutions that begin as desk-based prototypes and become devices that can survive in the real world – even more so within the marine environment. It’s one of the reasons Arribada focuses on open sourcing complete solutions, from the internal electronics to the enclosure design, meaning years of experience, failure, success, and all the lessons learnt in between can be shared going forward to help others succeed.

When considering what can be done to make the tags we manufacture and deploy more sustainable, the answer is complicated, as are all sustainability issues. From a marine hardware perspective, sustainability is an especially interesting discussion to unpack. Sure, devices on the surface can always ultimately be recovered on beaches or wherever they may come to rest. At that point, recycling, re-use, and recovery are valid options, especially if we’re talking about deploying many hundreds, if not thousands of drifting sensors. 

But for devices that are beneath the waves and attached to animals, what can be done to make those tags more sustainable? As we will never see these devices again, and therefore they will not ever be recycled or reused, surely there’s more that should be done to drive us towards a sustainable marine biologging future. To get at the answer, it’s probably best to break down the materials, components, and approach to developing and manufacturing solutions for the ocean.

First, let’s begin by breaking down the materials used to form a typical telemetry tag and start with the enclosure. For protection from water-ingress, most tags utilise an epoxy resin that is poured into a tool (cavity) in a liquid form to encapsulate the electronics and batteries inside. Epoxy resins (polyepoxides) are usually formed of four parts, a monomeric resin, a hardener, an accelerator and a plasticizer. When mixed together a chemical bond is formed that in turn results in curing, and after a period of time a hard finish. As epoxy resins are essentially thermoset plastic, once bonded, mixed, and cured the process cannot be reversed, meaning it’s typically not possible to recycle them. 

If properly polymerized (mixed perfectly), an epoxy resin is also inert and will not biodegrade, which is exactly why they are useful to protect electronics inside tags for numerous years. Constant immersion in saltwater shouldn’t degrade or break down the epoxy resin enclosure. So what options are available to improve the sustainability of biologging enclosures destined for a life spent permanently in the ocean?

Part bio-based (plant) epoxy resins 

Epoxy resins such as EcoPoxy are now available and contain a percentage of plant-based materials, i.e FlowCast contains 20% biobased carbon content. These could be tested and compared against epoxy resins used today to ascertain if they can match the strength and UV resistance needed to become a valid replacement, meaning tag enclosures could be manufactured using part biobased materials. Additionally, epoxy resins can be sourced that are free from volatile organic compounds (VOCs), meaning they won’t emit toxic gasses when curing. Switching to different epoxies opens up risk, so there will need to be extensive testing. But if successful, part bio-based epoxies would reduce the quantity of plastic used in each and every biologger manufactured.

Let’s next turn to the electronics inside the tag. Over 50 million tonnes of electronic waste (“e-waste”) is produced globally every year, so focusing on recyclability and a switch from single-use plastic is key to opening up access to a sustainable future in electronic manufacturing. 

One area of development is a move towards sustainable printed circuit boards (PCBs). Considering every biologger has at least one PCB inside, this idea is quite a hot topic. There’s plenty of scope to introduce sustainable PCBs into the biologging manufacturing process, and doing so would have a significant positive impact on the sustainability of these tools.

Natural fibre-based recyclable PCB substrates 

A number of PCB manufacturers have started to focus on sustainable PCB substrates. One such provider is JIVA, who have developed Soluboard. Instead of using copper and plastic, Soluboard combines natural fibres with a halogen-free polymer, meaning it is equally as flame retardant as standard PCBs and can handle reflowing (replacing electronic components), although I couldn’t find any information on the number of layers Soluboard can support at this time. Even if it is a single layer substrate, there’s plenty of scope to utilise Soluboard and other recyclable PCB substrates to reduce the percentage of plastic used in manufacturing if incorporated in designs from the start.

Lastly, we have the batteries. Nearly all biologging tags will utilise lithium batteries to pack as much capacity as possible into the limited space and without introducing additional weight. Typically, biologgers utilise primary non-rechargeable cells (Lithium Thionyl Chloride) or rechargeable (Lithium-ion or Lithium polymer). Demand for lithium has skyrocketed, with a prediction that it could triple by 2025 compared to 2020. But an increase in demand also means increased mining and extraction. In Chile, 30 square miles of land have been converted to pump brine to the surface where lithium-rich concentrate is extracted; at the same time, this operation consumes vast quantities of water, parching the local environment, displacing water tables, and disrupting habitat for Andean flamingos. To decrease this demand, we must find alternatives to lithium batteries. So what are the current potential alternatives to lithium batteries in biologgers?

Sodium-ion batteries 

One promising solution is the introduction of Sodium-Ion battery technology (Na-ion), offering superior environmental credentials, enhanced safety, and better raw material costs than lithium-ion (Li-ion); however, we’re not there yet. Large battery manufacturers are still investing in research to scale lab-based successes and unlock manufacturing at scale, which is no small feat. With the acquisition of Faradion by large industry players (a UK sodium-ion specialist company), it’s an evolving space that we will have to watch closely. Of this potential solution, Wood Mackenzie research analyst Max Reid says, “Sodium-ion technology is still in its infancy but represents a viable alternative to Li-ion technologies, depending on how far companies are willing to invest.” 

It may feel like a drop in the ocean comparing the quantity of batteries used in marine biologgers to, say, the electric vehicle industry, yet the destructive processes to extract lithium remain the same regardless of use. While we are connected to the same extractive industry by our technology’s needs and limitations, it is in our interest to support a move to viable sustainable alternatives and more sustainably manufactured biologging tags. 

So can we improve the sustainability of marine telemetry tags? Yes, there are several areas where we can push forward, having explored part biobased epoxy resins, natural-fibre based printed circuit boards, and pointed a finger at sodium-ion batteries (when they become commercially available) as a start.

But for us to really see and understand the coming possibilities will take investment in research by commercial manufacturers, as significant changes like switching to fibre-based printed circuit boards will mean re-testing performance, ensuring quality assurance can be achieved, and confirming modifications to designs are acceptable, all of which takes time, costs money, and requires trust. The same will be true if epoxy resins are changed, or if other sustainable materials and options we haven’t yet thought of become possible in the future.

But if successes are shared openly, we can move forward together step by step and create the sustainable future we want to see within the marine biologging community, and through example, throughout the wider conservation technology field.

Download the Sustained Effort Series

This article is from our latest editorial series, Sustained Effort: Community Thoughts on Conservation Tech Sustainability

Our series Sustained Effort brings together conservation tech users and makers to share their own perspectives on this topic. Through these case studies, we'll consider the current challenges of working sustainably in our field, but more importantly, how we can all take realistic, practical, and effective steps toward not only lessening our negative impact right now, but discovering larger steps toward the longterm, system-wide change needed to make conservation technology truly sustainable for our planet.

The entire Sustained Effort series is now available to download here on WILDLABS.

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