Marinus Link: Hitachi Energy’s grid-forming HVDC technology drives Australian renewable energy superhighway - Hitachi Energy

Hitachi Energy will supply grid-forming HVDC technology for the Marinus Link, the proposed submarine cable connecting Tasmania's renewable output to Victoria. Grid-forming converters inject voltage support into the AC network, steadying frequency and voltage when synchronous generators are absent. The article frames this as enabling a "renewable energy superhighway" and cites Hitachi Energy's confidence in the technology's capability to manage a high-renewable grid.

Where this fits

Marinus Link is a $35 billion transmission bet that Tasmania's wind and hydro can supply mainland demand, but the project highlights an uncomfortable truth: grid-forming HVDC is expensive firming infrastructure required because the grid runs on weather-dependent generation. The cable itself is not new; what matters is that grid-forming converters must now substitute for the synchronous inertia and voltage support that coal and gas plants provided for free. This cost, towers, cables, converters, losses, is part of the whole-system price of a renewables-only grid. It is also entirely Australian-owned problem-solving, shifting sovereignty risk but not eliminating it: Hitachi Energy manufactures these converters, and supply-chain resilience for critical grid hardware remains fragile.

What it means

Marinus Link will work. Grid-forming HVDC is proven technology. But the $35 billion budget is the price of replacing dispatchable power with weather-dependent supply plus the transmission and firming gear needed to make it reliable. That cost, borne by consumers and taxpayers, is the hidden denominator in every claim that renewables are "cheap." A firm, energy-dense alternative, nuclear, would eliminate the need for Marinus entirely and free that capital for other uses. Australia's renewable transition is locked into hardware, not fuel; that is an advantage over coal dependence, but it is not freedom from supply-chain constraint.