Elizabeth Tower, London

Westminster Bridge, London. Photo by Hugo Sousa on Unsplash

Today, humans will extract almost 100 million barrels of oil from the Earth. The size of this continuous flow of black sludge is difficult to visualise but let’s try; combined with the extraction of coal and natural gas, the flow rate of fossil fuels out of the Earth every second of every day is equivalent to the discharge rate of seven Thames Rivers – if they were filled with oil. Meanwhile, renewables and nuclear power amount to about a single Thames River equivalent discharge of oil. In the latest IPCC 1.5 degree report, the deadline for halving this flow is 2030, and eliminating it is 2050.

It is the dawn of a pivotal decade for humanity, and our society faces an unprecedented transition – can we clean up these massive veins of fossil fuel energy in time to prevent irreversible climate damage?

Maybe. But we need to start scaling up technologies as soon as possible, particularly energy storage technologies.

Renewable energy resources such as wind and solar have enormous potential for low-carbon, low-cost generation, but are not seamless substitutes for traditional fossil fuel technology. Specifically, solar and wind resources are inherently variable; the sun goes down, and the wind stops blowing. Moreover, they are often geographically distant from where power is ultimately required. Large scale, affordable energy storage and distribution technologies are the missing links in enabling widespread green energy penetration – look at the energy storage in stockpiles, tanker trucks, pipelines, trains, and ships full of fossil fuels all around the world today.

What are some energy storage options that can be deployed in the 2020s at the scale and usefulness of fossil fuels?

One of the most promising technologies is called ‘green ammonia’. Green ammonia (NH3) is an energy dense chemical that is produced from renewable electricity, air, and water (including desalinated sea water). That is it. Three ingredients: air, H2O, and renewable electricity. Not only is green ammonia renewable to make, but the by-products of turning green ammonia back into energy are, once again, air and water. It is fundamentally carbon-free!

In many ways, this molecule can flexibly replace fossil fuels, as it is substantially more energy-dense than batteries and it is already stored, piped, and shipped around the world today. Some energy applications for green ammonia may be seasonal energy storage, mediating overseas green energy trade, and decarbonising heavy-duty transport, namely the maritime sector. Momentum is proliferating, and the largest shipping engine company, MAN Energy Solutions, plans to have an ammonia dual-fuelled engine on the market by 2023.

How close are we to deploying this technology?

I can attest: very close. I work at the world’s first roundtrip green ammonia pilot plant (power-to-ammonia-to-power) built by Siemens, STFC, University of Oxford, and Cardiff University at Rutherford Appleton Labs in Oxfordshire. A demonstration unit is encouraging– but there is no time to waste! The next plant has been announced in Australia for start-up in 2022, at a staggering 2,000 times larger than the Oxfordshire plant. Humans have been making ammonia for decades, with industrial scale ammonia plants running in 64 countries today. While the ‘green’ process is slightly different, the relevant technologies are well understood and, thus, this technology actually can be scaled to fossil fuel scale in the 2020s. Other plants are under consideration in New Zealand, Norway, Morocco, Chile, the Netherlands, and the USA.

In my D.Phil, I design and model ‘green’ ammonia systems that disrupt the energy landscape and accelerate society’s transition to sustainable, carbon-free energy. I am specifically investigating applications in developing countries that need to meet growing demands without involving traditional carbon-intensive pathways, such as coal and natural gas.

There are many remaining questions about green ammonia: Will the oil and gas majors become ammonia companies? What are the geopolitical effects of democratised fuel? What policy is needed to enable the market to begin adopting this fuel in earnest? How can developing countries invest in more expensive, yet ‘green’, energy infrastructure?

The challenge of the energy transition is multifaceted – from providing zero-carbon fuels for ships to providing heat in our homes. These various demands require energy at different scales, in different places, and at different times. Eliminating our dependence on fossil fuels is not trivial, but green ammonia is one potential technology that is Thames-river-scale and ready to be deployed in this decade.