The Land of the Rising Sun has bet big on hydrogen, and today it cashed in. Japan officially opened its first nationwide hydrogen fuel network, a sprawling infrastructure of pipelines and refuelling stations that the government hopes will power everything from cars to power plants. At first glance, it is an ambitious leap into a low-carbon future. But for the markets, the real question is not whether the technology works; it is whether the economics add up.

Let's start with the numbers. The Japanese government has poured billions of yen into this project, subsidising both supply and demand. They are betting that hydrogen will eventually compete with natural gas on price, but that day remains distant. Current production costs for green hydrogen – made from renewable energy – are roughly three to four times higher than natural gas. The government’s plan relies on economies of scale and technological breakthroughs to close that gap. This is a classic first-mover gamble: spend heavily now, reap rewards later.

But here is where my scepticism kicks in. Japan is already saddled with the highest public debt among developed nations, over 250% of GDP. Funding a hydrogen network with taxpayer money while the Bank of Japan is slowly normalising interest rates is a recipe for fiscal strain. Investors are watching the yield on ten-year Japanese government bonds creep up; a sustained rise could crowd out private investment. The hydrogen highway may be green, but the fiscal road ahead is paved with red ink.

Then there is the demand side. Toyota has been the champion of hydrogen fuel cells, but global sales of their Mirai sedan have been modest. Without a robust fleet of hydrogen vehicles, the refuelling network risks becoming a white elephant. The government has mandated that transport companies and local authorities adopt hydrogen trucks and buses, but enforced demand is a fragile foundation for a market. Private capital follows profitable opportunities, not ministerial directives.

The market implications are straightforward. If Japan’s gamble succeeds, it could create a new export industry and reduce reliance on imported LNG, strengthening the yen. But if it fails, as the US freeway network did for electric vehicles in the 1990s, the losses will be borne by taxpayers and shareholders in Japanese energy firms. For now, the bond market is giving the project a cautious thumbs-up, but volatility in oil prices or a sudden shift in climate policy could quickly change that.

Across the Channel, Europe is watching with interest. The EU has its own hydrogen strategy, but it is far less centralised. Japan’s experiment will serve as a real-world test of whether a top-down approach can accelerate the transition. My bet? The hydrogen highway will eventually be profitable, but not on the timeline politicians promise. Patience is a virtue in markets; it is a luxury in politics.

So, sound the trumpets for Japan’s hydrogen vision. But keep a close eye on the national debt clock. In the City, we know that the road to hell is paved with good intentions and government bonds.