Hydrogen: a cage fight with the laws of physics

When energy ministers meet later this month one of the few things they’re likely to agree upon is hydrogen. More specifically, a ringing endorsement to the imminent release of a national hydrogen strategy in Australia.

Japan and International Energy Agency have already released hydrogen strategy papers this year. Global interest in developing a hydrogen economy is the product more of necessity than invention. Industries like steel and cement and heavy transport have limited options in a decarbonised world. They require a clean industrial fuel.

Energy importing industrial economies like Germany and Japan increasingly see hydrogen as their best bet. The plan is to be able to switch to importing zero emissions (green) hydrogen as a replacement to fossil fuels.

Australia is a natural counterparty to this deal, with the idea being to replace its declining multi-billion dollar exports of coal and gas to growing multi-billion dollar hydrogen in the future.

Sounds good in theory, but it won’t be easy. Wrangling industrial scale green hydrogen is like being in a cage fight with the laws of physics.

Hydrogen is not a new technology. The global hydrogen market is currently around 70 million tonnes a year, almost derived entirely from reforming natural gas and used in fertilisers and oil refining.

Industrial scale hydrogen was used to lift German airships in the 1930s and was the main fuel in “town gas” or syngas which was reticulated to homes and businesses in the middle of the 20th century.

The contemporary reference to hydrogen, like electricity, is an energy vector. With electricity, energy is coded into electricity and decoded instantaneously. Hydrogen is like a physical form of energy. That means it can be stored, moved and then released at some later place and time.

In simplest terms this coding of energy into hydrogen is done via electrolysis, where electricity is added to water. This separates it into hydrogen and oxygen. A hydrogen fuel cell is simply the reverse of this process, recombing the two gases to produce electricity and water.

Hydrogen was first used like this by NASA in the 1960s, who fitted fuel cells to its Gemini and Apollo spacecraft. Fuel cell cars were touted as possible solution following the OPEC oil crises in the 1970s and re-emerged in 2010 as a clean energy replacement for internal combustion engines.

Hydrogen has yet to break through because it has high costs and efficiency losses. Electrolysis is capital expensive and wastes around 40 per cent of the electrical energy used.

Green hydrogen can be produced from zero emissions sources like renewables. It can also be derived from conventional extraction processes using coal or gas, providing the carbon emissions are captured and stored (CCS).

That’s a big if. CCS has underwhelmed as a climate solution to date, not because it doesn’t work, but because it requires so much energy to work and doesn’t capture all of the emissions.

Renewable hydrogen remains prohibitively expensive. Its numbers are improving with the use of very cheap renewables, but offset by intermittency, which underutilises the high capital costs of the industrial scale electrolysers.

Once produced, hydrogen is difficult to store and move. Its small molecules means it leaks easily. To make pipelines or shipping cost effective means compressing it sufficiently. Hydrogen doesn’t like being compressed.

It liquifies at -253 C. By comparison natural gas (LNG) liquifies at around -161 C. The energy to hydrogen cost effective to moves also makes it not cost effective to compress.

Possible solutions to this include research into converting hydrogen into more manageable compounds like ammonia and methylcyclohexane (MCH). Both are easier to store and transport, and there’s even research into combustion engines using ammonia. But the catch is the process of transformation adds yet another energy loss.

Perhaps the  entry level application of hydrogen in Australia may be simply to use it as a battery: to use periods of surplus renewable generation to recharge fuel cells that can be dispatched during times of peak demand.

That would minimise the energy losses of storage and movement while creating a pathway to reduce costs over time. But its currently still an expensive option.

Continuing to explore ways to make the hydrogen supply chain work is highly desirable in a carbon constrained world. As Professor Alan Finkel’s imminent report will no doubt identify, carving out an Australian role as a potential supplier will be an important contribution.

Hydrogen is a challenging global research program that has been decades in development, and may take decades more to resolve. It is not an energy policy. Governments cannot promise a hydrogen future as a solution to climate change. They still need to hope for the best and plan for the worst.