Ann: DNV Engaged for Class Approval, page-2

Thinking outside the box

"construction time and costs for 1-tonne capacity tanks based on the Prototype Tank design and using the proprietary design of a multi-layered carbon steel tank with liner.
Suitable industry applications include marine bunkering and on-board storage tanks for new or modified ships
implementing compressed hydrogen as the fuel source. Discussions are under way with ship designers and owners
seeking alternatives to carbon fiber type 4 tanks stacked in containerized solutions."

Link to this Carbon fiber/steel cost compared is a bit old)

Steel is 'Usually' cheaper if weight is not the key. For stationary storage "The cost of carbon fiber compared to welded steel can vary depending on the application"

Interesting!