Hymonic produces hydrogen from ammonia cracking: “If it works in Rotterdam, it will work anywhere”
Using ammonia as a carrier, Hymonic makes hydrogen accessible and affordable to hard-to-abate industries. The Siemens Energy Ventures spin-off found the network of innovative partners and like-minded entrepreneurs it was seeking at climate tech hub SubZero, which supports startups both practically and strategically. Priya Gajadhar, COO and co-founder of Hymonic, and Iris Bergshoeff, Innovation Lead Climate & Energy at Platform Zero, explain why community is so important for startups.
This is part II of three in our series ‘Hydrogen in practice’, highlighting startups, fieldlabs and hubs in the region. Read the first part here about FLIE and FlowVolta.
Hydrogen ‘ZIP file’
Hydrogen is difficult to transport and store, so Hymonic uses ammonia as a carrier. Priya compares it to an ammonia ‘ZIP file’, in which the hydrogen molecules are temporarily stored. Where hydrogen is needed, the ammonia is fed into a cracker: a compact reactor that separates it into high-purity hydrogen and nitrogen. Ammonia can be transported using existing infrastructure, including pipelines, barges, rail and road. Hymonic offers a safe, affordable and scalable way to supply hydrogen to industrial, transport and maritime companies seeking to decarbonise in locations where hydrogen supply or storage is challenging.
Until 2025, the startup was part of Siemens Energy Ventures; it now operates independently. The shift made Priya realise what they had lost. More than an office or a test site, she was looking for a community of like-minded entrepreneurs: “You need more than just a physical space. We were looking for a place with other founders focusing on hardware — somewhere to exchange ideas, share knowledge and access the right industry networks.”
“We chose SubZero because of our focus on hardware and chemical processes ”
SubZero connects climate startups and industry
During her search, Priya attended a Platform Zero event, the organisation behind SubZero. At SubZero, startups, scale-ups and industrial partners work on clean and circular technologies for the port and industry. The community event at the climate tech hub gave her a clear sense of the people, the atmosphere and the value of the network: “Rotterdam and Delft offer several good options, but we chose SubZero because of our focus on hardware and chemical processes. We immediately felt at home.” InnovationQuarter and Rotterdam Partners supported Hymonic’s relocation to SubZero, introducing the startup to the regional ecosystem.
For Iris, Hymonic is exactly the kind of company SubZero was created for. She explains, “Our purpose is to support innovators who contribute to future-proofing Rotterdam’s port and industry and driving the energy transition.” Since late 2025, SubZero has brought these companies together at its new M4H site in Rotterdam, with office facilities and a large industrial hall where they can build, assemble and produce their technologies. “There is plenty of space, but it fills up fast”, says Iris. “So, we carefully select who we work with — companies we believe can accelerate climate impact across maritime, energy and industry.”
“Rotterdam is an important place for many companies to prove themselves ”
If it works in Rotterdam, it will work anywhere
Rotterdam is the gateway to the hydrogen ecosystem in South Holland, where end customers, partners, the port authority and the industrial cluster work in close proximity. Iris says, “The Port of Rotterdam is known around the world for its innovative mindset and for having a strong and highly engaged ecosystem. That makes Rotterdam an important place for many companies to prove themselves.” Priya adds, “If it works here, it will work anywhere.” Iris sees the advantages flowing both ways: “A hub like SubZero also benefits the port. To stay future-proof, you need to attract innovation.”
SubZero has raised Hymonic’s profile, strengthening its position within the ecosystem. “We now have easier access to relevant sectors, including the maritime industry, and are approached about partnerships and funding opportunities”, says Priya. “Sometimes, organisations find us precisely because we’re part of SubZero.” Iris believes proximity makes all the difference: “When people see and speak to each other regularly, they are much more likely to co-create and build new ventures together.” That is SubZero’s strength: connecting companies that can help each other grow.
“We have easier access to relevant sectors” – Priya Gajadhar, COO and co-founder Hymonic
From pilot to semi-industrial production
The hydrogen ecosystem can be hugely valuable for startups, but it is not always easy to navigate. Priya agrees: “When you start out, you often don’t know where to go.” With so many hubs, schemes, partners and support channels, the landscape can feel fragmented. SubZero helps young companies find their way through that complexity. At the same time, the hub has to be selective. It needs to stay financially sound while also attracting companies that genuinely contribute to sustainability. A strong ecosystem is not about bringing in as many players as possible; it is about making the right connections between them.
Hymonic is now entering its next phase: installing its first commercial reactor system for a customer and moving towards a key investment decision. Priya also wants to attract new talent and bring the company’s main R&D activities closer to home. With high-quality testing infrastructure for power-to-X technologies, the Fieldlab Industrial Electrification (FLIE) pilot hall at SubZero is an ideal location.
For Iris, this is where SubZero’s practical role comes in, not as a final stop but as a place for companies to evolve: “We support startups from the pilot stage to the first semi-industrial production phase. After that, we hope to keep thinking along with them as they continue to scale.” InnovationQuarter actively helps attract new test projects to the pilot hall, boosting the field lab’s development as a hotspot for clean and circular innovation.
The value of community
Priya feels that SubZero’s value lies in its community: “It’s about sharing experiences, exchanging tips and best practices, finding recognition and gaining access to a substantial network.” Seeing other founders face similar challenges is valuable too. “You don’t get that in an anonymous office building where people share nothing but a desk.” Her advice to other startups is to take the time to understand who they are and identify the expertise, partners and facilities they need to move forward. The extensive ecosystem of South Holland offers plenty of opportunities to do just that.
Is your startup helping to make Rotterdam’s port and industry more sustainable and future-proof? If you’re looking for a partner to support you with testing, validation and scaling up, get in touch with SubZero.
