NH3Craft project yields seaworthy composite tanks for ammonia storage
Connova Deutschland has developed the glass fiber-wound Type 4 vessels as a lightweight, corrosion-resistant alternative to steel tank systems for the maritime sector’s shift toward fossil-free fuels.
Close-up of several manufactured seaworthy fiberglass composite tanks with integrated stainless steel connection elements, stored on wooden pallets for safe transport. Source (All Images) | Connova Deutschland GmbH
Connova Deutschland GmbH (Klipphausen, Germany) has developed and manufactured Type 4 composite pressure vessel tanks designed to store liquid ammonia for use as a maritime fuel, marking a key milestone in the EU-funded NH3Craft project aimed at enabling zero-emission shipping.
Launched by the EU in 2022, NH3Craft involves 13 European partners from research, industry and shipping. The project targets ammonia (NH3) as a replacement for heavy fuel oil — a fuel that, when burned in ship engines, emits large quantities of CO2 and other pollutants. Ammonia can be produced from electricity, hydrogen and atmospheric nitrogen, stored under relatively simple conditions and combusted locally without CO2 emissions.
As the composite specialist on the project, Connova Deutschland was responsible for the development and manufacture of the tank systems. According to Connova, the tanks required proof of compressive strength up to a test pressure of 5 MPa, long-term leak tightness to prevent toxic outgassing, process-reliable integration of stainless steel connection elements into the composite structure, and high corrosion and media resistance for saltwater environments.
An engineer inspecting a large test module with several composite tanks for ammonia.
To meet these requirements, Connova’s engineers selected a Type 4 tank structure with a multi-material design. At the core, a rotationally molded liner provides media tightness and integrates securely with boss elements. The liner also functions as a permanent winding mandrel, eliminating the need for complex tooling and reducing production costs. A filament-wound composite structure surrounds the liner to provide structural integrity up to the burst pressure threshold. The tank laminate was built entirely with glass fibers — chosen both for corrosion resistance in saltwater environments and to address the cost sensitivity of the maritime industry.
The resulting tank systems offer a nominal volume of one cubic meter and hold approximately 680 kilograms of liquid ammonia at 18 bar operating pressure. This corresponds to roughly 70% of the gravimetric energy density of conventional fossil fuels.
Connova says the successful delivery and testing of the tank systems for the NH3Craft project demonstrates composite manufacturing’s potential to support the adoption of environmentally friendly energy carriers in the maritime sector.
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