Whether Japan's shift to hydrogen causes *more* or *less* carbon emissions than the status quo depends to an alarming extent on a relatively obscure issue of international carbon accounting (): https://twitter.com/DavidGaian/status/1336782504942956544

There's two main approaches to international emissions accounting: Consumption-based and production-based.

Production-based emissions are the main way of doing the sums, and only count emissions that happen on a country's territory towards its total: https://twitter.com/KetanJ0/status/1336783428503674885

Consumption-based emissions also take into account the effects of trade. So, for instance, a Chinese-made iPhone sold in the UK is counted towards the UK's total, not China's:

https://ourworldindata.org/consumption-based-co2

Now let's imagine Japan switches 25% of its primary energy demand to hydrogen. And the hydrogen in question is made from coal without carbon capture and storage, like the test project being run now in Australia for the Japanese market: https://www.ft.com/content/5a18dc92-ae8c-4b27-98fc-ed7f1465980e

What happens in this situation is that Japan's production-based carbon emissions fall dramatically. You're switching an imported fuel that emits carbon when it's burned in Japan (coal or gas) to a different fuel, hydrogen, that emits no carbon when it's burned in Japan.

However, *consumption-based* carbon emissions could well go UP! Producing that hydrogen in Australia, not to mention converting it into a transportable form and shipping it to Japan, will likely cause more emissions than just shipping coal to Japan.

This is a major problem! Japan's emissions haven't gone down, they've just been elided by some accounting sleight-of-hand.

Now to be sure, they don't vanish completely. Australia's production-based footprint would go *up* because of emissions from the coal gasifier.

And the proposal with that Australia-to-Japan hydrogen export project is that the carbon emissions will ultimately be sequestered in depleted offshore oilfields.

But such carbon capture has never really worked despite all the talk. You wouldn't want to count on it.

In addition to which, no one thinks that such "blue hydrogen" with carbon capture is viably a zero-emissions technology. If it works it could be lower than fossil gas, but not necessarily by all that much.

https://www.bloomberg.com/graphics/2020-opinion-hydrogen-green-energy-revolution-challenges-risks-advantages/oil.html?sref=5JzLFdzD

It's worth bearing in mind that the main likely exporters of grey or blue hydrogen are fossil fuel exporters like Australia, Saudi Arabia, and maybe Russia -- countries that we know have been reluctant to sign up to the net zero targets proposed in places like Japan.

So one alarming vision of the future is that places like Japan, China, the U.S. and Europe proclaim themselves "net zero" while relying on massive and uncounted offshore emissions from grey or blue hydrogen production in countries like Australia, Saudi Arabia, or Russia.

Would that make those hydrogen-exporting countries pariahs? Maybe! But the net zero countries would be depending on them to prop up their own carbon-accounting fictions, so you could see them muddling through, like they do now as the world's biggest fossil fuel exporters.

This is why it's important that policy is robust and forward-looking, as @ClaraDFMarques argues here, to encourage zero-carbon *green hydrogen* made from renewables rather than the polluting alternatives. https://www.bloomberg.com/graphics/2020-opinion-hydrogen-green-energy-revolution-challenges-risks-advantages/policy.html?sref=5JzLFdzD

There's huge potential in the switch to hydrogen, but right now it's a gold rush. Everyone is rushing out to stake their claims in an environment where regulation and public understanding is way behind where the industry is heading. That often leads to very bad outcomes.

So governments and the public need to get up to speed, and fast. Every announcement and move on hydrogen needs to be scrutinized with clear eyes with the question: "Does this reduce *global* carbon emissions compared to the status quo?"

We need IMO to be pretty single-minded in driving as fast towards green hydrogen as we can. And recognizing that in climate terms it's a very different technology to blue and in particular grey hydrogen.

(ends)