In the ever-evolving realm of underwater technology, German firm SubCtech stands out with its innovative approach to ocean monitoring and subsea power solutions. 
Guided by the expertise of founder and CEO Stefan Marx, the company has carved out a significant niche in this highly specialised industry. Both here discuss SubCtech’s pioneering products, the challenges of subsea engineering and the sustainability of modern subsea energy storage.
Based in Kiel, Germany, SubCtech has two primary business units – Ocean Monitoring and Ocean Power. The company began by manufacturing products to monitor seawater quality, and, over time, its focus evolved to meet the increasing demand for battery power underwater.
From its relatively small beginnings, crafting small underwater batteries, the firm now boasts a staggering 1 MWh battery storage system set to be in operational use from beginning of 2024.
SubCtech’s Ocean Power unit manufactures subsea batteries that can be deployed aboard underwater vehicles – particularly unmanned vehicles – or as backups for Oil & Gas industry applications offshore. To ensure its customers are comprehensively serviced, the Ocean Power unit is subdivided into three sectors: offshore energy, underwater vehicles, & standard subsea power products.
According to founder and CEO Stefan Marx, SubCtech’s Ocean Power unit offers both standard batteries and bespoke solutions, “We are able to offer solutions that fit into the customer’s available space and within its weight limitations – that’s where our roots lie, and that’s the service that has delivered our growth thus far.”
Record-breaking storage
The company’s engineering prowess was on full display in late 2023, with SubCtech’s unveiling of the latest, greatest and biggest battery that it has ever produced: a jaw-dropping 1MWh battery storage system.
The battery, which was produced to order for a client, is the first subsea MWh battery in the world. But it is also only one amongst many other batteries sold by SubCtech each year. The company’s off-the-shelf battery solutions – dubbed ‘Big Jim’ and ‘Long John’ – are perennial best-sellers. Both battery units have standard physical dimensions and similar weights, but the innards can be customised according to the customer’s specific requirements, including for both the capacity and voltage, both within set limitations.
For vehicle-based solutions, SubCtech offers three different standard battery housing diameters, namely 260mm, 310mm and 416mm internal diameter sizes. Bespoke sizes, energy, power and voltage ranges are meanwhile available on request.
Quality German engineering
SubCtech was founded in 2010 by current CEO Stefan Marx, who boasts over 30 years’ experience working in ocean-related industries in various scientific and business roles. The company was originally headquartered in a small town near Kiel, but soon moved into Kiel proper, where its staff-count has gradually risen from 20 to 80, in order to accommodate growing demand for the company’s products.
Following several relocations around Kiel to accommodate its growing workforce and workload, SubCtech has put down roots via the construction of its own production space. Its new facility includes 1,300m2 of covered space and 1,500m2 of outdoor/storage areas. A move to a 4,000m2 building is planned.
SubCtech’s products are qualified according to military standards, and all are certified by Det Norske Veritas (DNV), an internationally accredited registrar and classification society headquartered in Norway. This DNV certification, which seeks to guarantee the safeguarding of life, property and the environment, ensures not only total peace of mind for users of the company’s products but crucially, it is also a legal qualification for any equipment fitted to the deck of a vessel.
Concluding, Mr Marx highlights how the company’s best assets are driving it forward, “We’ve learned over the years that even as a medium-sized company, we’re able to move the world a little bit. Today, we have the best products with a great reputation and a high-quality team. In my 30 years in the industry, that’s the recipe for success. If you want to learn more about our company and our products, visit us at Oceanology Internation in London at Booth J300!”