Repowering coal and *decarbonisation strategies* | The Bryden Wood podcast \\Jaimie Johnston MBE, Kirsty Gogan FEI FRSA, Terra Praxis
There are two terawatts of coal still projected to be operating at mid-century – enough on its own to consume our entire remaining carbon budget. Retiring that infrastructure is politically and economically unrealistic. But what if you didn't have to? What if you could swap the heat source, keep the jobs, keep the grid connection, and decarbonise the plant? That is the proposition at the heart of Terra Praxis – and the subject of this conversation between Jaimie Johnston MBE and Terra Praxis co-founder Kirsty Gogan.
The Impossible Burger for climate:
Kirsty Gogan is an environmentalist who spent her career working on sustainability, including as a civil servant for Deputy Prime Minister John Prescott, as a consultant for Greenpeace and Ben & Jerry's, and as a forest-planting activist. She was, by her own admission, anti-nuclear by default. That changed when she read Professor Sir David MacKay's Sustainable Energy Without the Hot Airand realised she wasn't educated about nuclear energy – she had simply inherited assumptions that didn't hold up.
That intellectual honesty runs through the whole conversation, and it is what makes Kirsty's advocacy for advanced nuclear so compelling.
The repowering proposition
The core idea behind Terra Praxis's Repowering Coal initiative is deceptively simple: co-locate an advanced nuclear heat source next to an existing coal plant, decommission the coal boiler, and keep everything else: the steam turbine, the power island, and critically, the existing grid connection and transmission infrastructure. The result is a decarbonised plant that runs at a higher capacity factor and lower cost than the coal plant it replaces, with the potential to add additional value services such as hydrogen production and atmospheric carbon removal.
The numbers behind this are significant. The Princeton Net Zero America report found that if the United States could repower all of its existing coal plants, it would reduce the amount of new transmission infrastructure needed by 40%. There are 260 gigawatts of coal still operating in the US alone. And globally, more than half of the coal fleet is less than 14 years old – with a trillion dollars of unrecovered capital. Retirement of these assets is not just economically unattractive; in many parts of the world it is simply not going to happen.
Repowering preserves the economic infrastructure of coal-dependent communities: jobs, tax revenues, local economies – while eliminating the emissions. As Kirsty notes, the plants when repowered would likely be more profitable than they were before.
Beyond electricity – clean drop-in fuels
The conversation extends well beyond coal into what may be an even larger opportunity: the production of clean, drop-in substitute fuels using very low-cost hydrogen derived from advanced nuclear heat.
Kirsty introduces what she calls the 'Impossible Burger' analogy. The Impossible Burger is a plant-based meat substitute available at every Burger King in America – it looks, tastes, and costs the same as a regular burger, and it doesn't require behaviour change. Terra Praxis's vision for clean fuels follows the same logic: produce synthetic hydrocarbons and ammonia that can be distributed through existing storage, transport, and end-use infrastructure, used in existing planes and ships, and priced comparably with the fossil fuels they replace. No new infrastructure. No behaviour change. Just a cleaner version of what already works.
For this to be viable, hydrogen has to cost less than a dollar per kilogram – a target that is, Kirsty argues, out of range for renewables alone but achievable through advanced nuclear heat sources manufactured at scale in shipyard-based production environments.
The scale of the problem
The statistics Kirsty presents are sobering. Coal-fired capacity currently emits around 15 billion tonnes of CO₂ per year – nearly half of all carbon emissions. A hundred million barrels of oil are consumed every day. Major energy forecasters – the IEA, EIA, DNV, BP – all still project more than half of global energy coming from fossil fuels by mid-century, putting the world on a three to four degree warming trajectory.
And the demand projections may themselves be understated. If everyone in the world had access to a median level of energy, equivalent to the Czech Republic's per capita consumption, global energy infrastructure would need to triple. An estimated 850 million people currently lack access to any electricity at all, a number projected to rise to three billion by 2050.
Where Bryden Wood connects
The connection between Terra Praxis and Bryden Wood lies in delivery methodology. Repowering coal plants at the scale and speed the climate demands requires a scalable, manufactured building system – configurable to meet different site and plant requirements, accommodating a range of heat sources, and designed for highly automated assembly. That is precisely Bryden Wood's specialism. As Kirsty puts it, everybody who sees Bryden Wood's work in this space says the same thing: we should be building all our buildings this way.
Jaimie describes the Repowering Coal project as probably the biggest value problem statement Bryden Wood has ever had – and the biggest potential social impact the practice could make through a single initiative.
Jaimie Johnston MBE is Board Director and Head of Global Systems at Bryden Wood. Kirsty Gogan is co-founder and Managing Partner of Terra Praxis. This episode was originally released in December 2021.
