Hard Lessons with Hot Helium

In the wake of Europe's largest blackout in decades, commodities investor Alexander Stahel helps us to understand the physics of power grids, and how Spain's celebrated renewable transition became its Achilles' heel. He introduces the “hellbrise” phenomenon—excessive, rather than too little, renewable generation—as he considers the role of grid inertia in preventing minor disruptions from cascading into failures in mere seconds. Spanish energy policy isn’t the first time that green idealism has brushed over the fundamental requirements of reliable electricity, and it is unlikely to be the last. But it has certainly provided a stark example of the dangers that await such an oversight.

This week, we cover the recent blackout on the Iberian peninsula. Guillem Sanchis Ramirez, a Spanish nuclear engineer and advocate, walks us through the event that plunged over 50 million people into powerlessness and the power grid on which it happened. We cover Spain’s precarious dance with renewable energy, its political resistance to nuclear power, possible paths forward for the country’s energy supply, and our essential human reliance on stable electrical systems.Note: This interview was recorded on April 30, 2025, still in the midst of the story’s rapid development.

This week, we take a break from nuclear power to talk about larger systems: those of Planet Earth. Professor Andy Knoll, renowned Harvard geologist and author of A Brief History of Earth, reveals how life itself has shaped Earth's chemistry, climate, and geology. From the oxygenation of Earth's atmosphere to the potential colonization of Mars, we explore the constant and delicate dance between life and the planet.Read extended shownotes on Substack.

This week, we talk High Temperature Gas Reactors, or HTGRs, with a Decouple favorite: reactor designer and nuclear historian Nick Touran (What Is Nuclear | X). From the first conceptual sketch of an HTGR in wartime labs to today’s revival by players like X-energy and China’s fast-moving reactor fleet, we dissect what makes HTGRs unique—both in engineering promise and the difficulties that have long haunted their success. With helium cooling, TRISO fuel, and ambitions beyond electricity into process heat and industrial decarbonization, HTGRs may be poised for a comeback. But will history repeat itself, or finally break the cycle?Read longer show notes and support Decouple on Substack.

This week, we talk tools. With precision machinist Noah Rettberg, we explore a facet of modernity as important as energy, for it is the technology that energy powers and the technology that makes that technology: machine tools. Noah draws from his professional knowledge and passion for history to takes from Roman metallurgy through the guild-protected craftsmanship of medieval Europe to the steam-powered revolution in machining to the cutting-edge of metalworking tools. Riveting!

This week, we talk radiation—the elephant in the room during many conversations about nuclear power. Nick Touran, a reactor designer and nuclear historian, helps us along. While nuclear advocates have made remarkable strides in dispelling public fears about radiation, Touran warns against the pendulum swinging too far toward complacency. We explore why maintaining a healthy respect for radiation remains crucial even as we champion nuclear power's expansion.Read the extended shownotes on Substack.

Molten Salt Reactors are often portrayed as nuclear’s great missed opportunity, promising unparalleled safety, efficiency, and fuel sustainability. But are these promises reality or hype? Nick Touran, reactor designer and nuclear historian, joins me to tell the complex story behind molten salt reactors—from their ambitious beginnings during Cold War nuclear airplane experiments to the realities of managing radioactive liquid fuels. This conversation clears the mist around one of nuclear's most intriguing yet misunderstood technologies.Read more in-depth show notes on Substack.

This week, we talk Boiling Water Reactors (BWRs) with James Krellenstein, the CEO of Alva Energy. We dive into the engineering, history, and physics of these reactors, how they differ from other designs, and why the United States may have erred in not choosing the Advanced Boiling Water Reactor (ABWR) instead of the Westinghouse AP-1000 for the Vogtle nuclear power plant.For this episode, we’ve included a glossary below to help with unfamiliar terms:ABWR: Advanced Boiling Water ReactorATWS: Anticipated Transient Without ScramBORAX experiments: Historical experiments testing reactor limits through deliberate failuresBWR: Boiling Water ReactorCOPS: Containment Overpressure Protection SystemCRDM: Control Rod Drive MechanismESBWR: Economic Simplified Boiling Water ReactorFLEX: Diverse and Flexible Coping Strategies (post-Fukushima enhancements)FOAK: First of a kindIGSCC: Intergranular Stress Corrosion CrackingNOAK: N-nth of a kindNRC: Nuclear Regulatory CommissionNSSS: Nuclear Steam Supply System (N Triple-S)PRA: Probabilistic Risk AssessmentPWR: Pressurized Water ReactorRCIC: Reactor Core Isolation Cooling System RPV: Reactor Pressure VesselSLC: Standby Liquid Control SystemRead more on Substack!

This week, we talk industrial policy. Economist and author Steve Keen joins me to shine light on the present moment by exploring the historical use of tariffs and industrial policy in the development of industrial powers from Britain to China. In his usual style, Keen aims to dismantle the myths of free-market economics, explaining how virtually every successful industrial nation began with protectionist policies. With the US now engaged in a trade war with Canada and other nations under Trump's renewed tariffs, we examine whether such measures can effectively rebuild American industry without the comprehensive industrial policies that powered China's meteoric rise. Hint: Keen believes this simplistic tariff solutions may create more chaos than revival for America's industrial base.

Today, we talk uranium nuclear fuel. MIT Professor Koroush Shirvan, joins me to dive into the hidden complexities of nuclear fuels. From early fuel experiments that saw uranium rods turn into spaghetti-like structures under neutron bombardment to the intricate economics shaping the future of fuels like TRISO, Shirvan offers insights into the realities behind nuclear power’s remarkable yet challenging fuel technologies.Listen to discover how history shaped today's dominant fuel choices, why accident-tolerant innovations are critical, and about the economic realities that could either launch or limit the nuclear renaissance.