Sounds good, but has anyone done this in production anywhere, and if so, what did it cost? Hydrogen has a habit of leaking through anything and embrittling met

Sounds good, but has anyone done this in production anywhere, and if so, what did it cost? Hydrogen has a habit of leaking through anything and embrittling metals, so it may not be a trivial task. According to the Dept. of Energy, converting pipelines to carry pure hydrogen will require "substantial modification." https://www.energy.gov/eere/fuelcells/hydrogen-pipelines https://www.energy.gov/eere/fuelcells/hydrogen-pipelines