From the motherboard of a device to a server or IoT: in Belgium, it's all about circularity

The limitations of traditional refurbishment are becoming increasingly clear. As digital devices grow more complex, they also become harder to update, repair, or even reuse. A cracked screen or outdated software often spells the end for a smartphone or laptop, even though many internal components remain fully functional. But what if those components could live a second life?

Enter two Belgian entrepreneurs—Cyprien de Barros, founder of Sunflower, and Jean-Brieuc Feron, founder of Citronics—who are building circular models that rethink what tech waste can become. Instead of refurbishing whole devices, they extract and repurpose key components, particularly motherboards, to create new digital infrastructure.

Inside every phone or laptop lies a treasure trove of microelectronics still capable of powering useful tools. Yet in today’s linear economy, we discard them. These startups, grounded in circularity and innovation, are crafting resilient, localized alternatives to the dominant IT model—one motherboard at a time.

From Smartphones to Micro-Computers – The Citronics Approach

Jean-Brieuc Feron’s insight is simple: most smartphone circuits still work long after the devices are considered obsolete. “We throw smartphones away because they’re too old, too slow, or no longer receive updates,” he explains. “But the internal circuits are often still perfectly functional.”

Rather than extracting each component, Citronics reuses entire motherboards—initially from the Fairphone 2—to build micro-computers for IoT applications. “We never desolder the components. That’s the economic and technical strength of the concept. It just works,” Jean-Brieuc Feron says. His goal is to enable engineers to prototype with low-cost, reused materials and then to scale it up.

These micro-computers can be deployed in thousands of settings: vehicles, home automation, industrial systems, even solar panels. “IoT is everywhere—trains, planes, thermostats, electrical cabinets, etc.” Jean-Brieuc Feron adds. By simplifying the reuse process and avoiding new tech, Citronics keeps costs down while unlocking functional second lives for aging tech.

For the moment, Citronics only works with Fairphone 2 motherboards, but they are looking to expand their sourcing. "We’ve started working on smartphones that are harder to dismantle, like certain Samsung models that are glued together. They’re much more widely available compared to Fairphone” continues Jean-Brieuc Feron, “That means we can already justify investing in more advanced tools and processes—while still keeping the unit cost close to what we have today with Fairphones."

Building a Sustainable Cloud – The Sunflower Project

While Citronics focuses on embedded computing, Cyprien de Barros takes the cloud route. His project, Sunflower, carried out by his Startup Dimeritium, repurposes old laptop motherboards to build modular, low-energy servers. “There are herds of used computers everywhere. The next chip factory is in our drawers,” he says. “Sunflower is a test to decarbonize digital infrastructure.”

"I see myself as the refurbisher of the refurbishers”, continues Cyprien de Barros. “I'm taking machines that are considered completely unusable. In a way, I'm the sarcophagus, the pyramid that collects all these old motherboards destined for nothing—and turns them into the foundation of a sovereign cloud."

Cyprien De Barros has developed a five-layer stack: from 3D-printed motherboard racks using recycled plastic to open-source hypervisors and containerized software. “The 3D printers we use are public and accessible in any FabLab,” he explains. “Any European city could replicate this.” His servers already run at Greenbizz, a green tech hub in Brussels.

"Greenbizz is a core part of my strategy. I want Greenbizz to become a kind of center of excellence—to prove that with the right infrastructure, we can build data centers that are resilient, low-carbon, and modular” Cyprien de Barros details. The rooftop of Greenbizz is covered in solar panels, delivering clean energy on-site. "The Greenbizz model is simple: you're directly connected to solar panels, so whenever the sun is out, you're automatically running on the most decarbonized energy possible”, he concludes.

“I’m building a tiny OVH,” he jokes. “My servers provide web hosting, storage, video conferencing, all with second-hand parts.” And it’s not just sustainability—it's resilience. “They're less powerful, but I have many of them. That physical redundancy is a strength. It means I can replicate the model in Paris, Berlin or Tokyo, and even follow the sun to use the greenest machine at any hour.”

He details: "We’ll run the most decarbonized machine available for any given request. For example, if a query comes in at 2 a.m. in Brussels, we’ll route it to a server in Tokyo—because it’s daytime there, the sun is shining, and clean energy is available, unlike in Brussels where it’s night."

Circularity Meets Practicality – The Path Forward

Both Citronics and Sunflower embrace a subtractive refurbishment mindset: nothing added, no costly rework. “If I need to solder anything or create extra carbon footprint just to refurbish, it makes no sense,” Cyprien de Barros insists. It’s not just about reuse—it’s about smart, low-impact design that’s viable at scale.

Jean-Brieuc Feron agrees: “a smartphone that’s too old to refurbish as a phone has zero value. But its core components—CPU, Wi-Fi, 4G modules—are still worth over €100 if bought new, even ten years after the smartphone release.” “The components have become mid-range performance, but it's still perfectly usable for other applications”, he adds.

With standardized connectors, Citronics can combine motherboards from different brands to meet industrial demands. “An industrialist will be able to order 10,000 units from us, mixed between motherboards coming from Fairphone 2 and Samsung Galaxy J5 for example.”  

The approaches of the two entrepreneurs differ, but the philosophy is shared: stop defaulting to new. “We’re the only ones doing this, in Europe or globally,” says Jean-Brieuc Feron. “Our story is so unusual that it grabs attention. Once we show the technical and economic value, it’s easy for partners to commit.” For Sunflower, Cyprien de Barros concludes, “This is a proof of concept. I just want to show that a circular, sovereign cloud is possible.”

At GreenTech Forum Brussels, Cyprien de Barros will be showcasing his work at the Hub Brussels stand: “For the first time, I’ll be presenting a portable demonstrator—with 3D-printed racks and old motherboards. And just ten minutes away, at Greenbizz, there’ll be a full-scale setup: an actual server cabinet built entirely from these repurposed motherboards.”

Citronics and Sunflower offer different paths toward a common goal: building digital systems that are resilient, efficient, and decoupled from overconsumption. While economic viability remains key, their work proves that circular IT isn’t just ethical—it can also be practical and powerful.

In an era of escalating climate disruption, the IT sector can't afford to ignore its reliance on scarce materials, high energy needs, and vulnerable supply chains. Projects like these show how digital infrastructure can adapt, anticipate, and endure—especially when the tools already exist in our junk drawers. The next move? Scale it. Let go of “new by default.” And build tech to last.

Jean-Brieuc Feron is CEO of Citronics. Cyprien de Barros is CEO of Dimeritium that carries out the Sunflower project. Citronics and Dimeritium will be exhibitors on GreenTech Forum Brussels 2025