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chris keefer

@Dr_Keefer

May 13

The Gas Turbine: The final revelation in the pantheon of prime movers. A mega 🧵

Rockets, in the form of gunpowder charges rammed into bamboo, predate the Magna Carta. Water wheels powered medieval grain mills.

Steam piston engines drove the industrial revolution and Parson’s 1894 steam turbine continues to deliver most of the world’s electricity generation.

In the late 19th century Otto’s and Diesel’s internal combustion engines began to reorganize transportation, agriculture, warfare and bulk shipping of commodities.

The gas turbine emerged only in the 1930s. It is the most recent and the last prime mover. It has subsequently become the undisputed champion of global aviation and increasingly a dominant source of dispatchable electricity on grids around the world.

Demand for gas turbines is now surging as AI data centres require rapid additions of baseload power.

John Barber patented a recognizable gas turbine cycle in 1791, describing a compressor, a combustion chamber, and a turbine wheel in sequence. John Brayton worked out the thermodynamic cycle that still bears his name in 1872. By the time Frank Whittle ran his first jet engine prototype in 1937, engineers had been sketching versions of the same concept for 65 years.

A gas turbine is, at its core, a device that compresses air, adds fuel and combusts it to produce extremely hot gas to spin a turbine. As engineers push the thermodynamic limits through hotter temperatures the engineering reality is that the hot gasses leaving a modern combustor are well beyond the melting point of the alloys from which the turbine blades are made.

The compressor in a large commercial engine reaches pressure ratios above 40:1, requiring blade geometries machined to tolerances measured in microns across components spinning at thousands of revolutions per minute. In aviation applications the containment structure must be light enough to fly and strong enough to survive a blade release without sending a fragment through a fuselage.

The extreme safety and reliability requirements in aviation and power generation impose a slower pace in innovation cycles reminiscent of the nuclear industry. In the end the gas turbine’s limits are defined by the cumulative materials and manufacturing knowledge required to operate at the edge of its thermodynamics. These factors determine who can build it, and why it is one of the few technologies that the West still decisively dominates, for now.

The following essay is based on a conversation on the Decouple Podcast with Dr. David Helmer, a veteran of GE Global Research and the American Society of Mechanical Engineers (ASME) K-14 gas turbine heat transfer committee.

The impetus for the development of the gas turbine

What finally shifted the gas turbine from blueprints to a functioning engine was the pressures of a World War in which aviation had become increasingly central. Through the 1930s, piston engines remained the only practical option for powered flight, and their limitations were becoming a military liability.

Piston engines struggle at higher altitudes, where thin air starves combustion and power drops sharply. They are mechanically complex, with hundreds of reciprocating and rotating parts subject to vibration, wear, and failure.

Their power-to-weight ratio, while adequate for the propeller aircraft of the era, left little room for the performance gains that military planners were demanding: greater speed, higher altitude, longer range. Frank Whittle in Britain and Hans von Ohain both recognized that the piston engine had reached a ceiling that the Brayton cycle could break through.

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chris keefer

@Dr_Keefer

Apr 30

Understanding why this Uranium cycle may not follow the same script as previous cycles requires understanding something fundamental:

Uranium is a commodity unlike any other, governed by market mechanics that have no real parallel in oil, gas, or industrial metals.

The history of uranium investing is largely a history of analysts importing mental models from those markets and being destroyed by them.

Grant Isaac, President and COO of @Cameco Corp and a former dean of the Edwards School of Business at the University of Saskatchewan, laid out that case in a recent conversation on Decouple. What follows draws on that interview as its primary analytical frame.

A thread🧵 (full essay on decouple.media substack)

1/ Uranium equities have had a strange few years.

The stocks of major producers have surged, junior developers have attracted capital at valuations that would have seemed delusional a decade ago, and the long-term contract price has moved steadily upward without the violent reversal that ended every previous uranium bull market on record.

Investors who lived through prior cycles keep waiting for the blow-off top. It has not come.

The standard explanation is that nuclear power is back.

After a decade of retreating political support following Fukushima, governments across the western world have rediscovered that a 24-hour, carbon-free, energy-dense power source is not something you can replicate with wind turbines and battery storage.

Reactor life extensions, phaseout reversals, a Chinese nuclear construction boom, and corporate power purchase agreements from data centre operators hungry for firm baseload have all landed within a compressed window.

The demand story is real.

But demand alone does not explain why this bull has behaved so differently from its predecessors. Previous uranium cycles also had credible demand stories.

The 2005-2011 bull had a nuclear renaissance narrative, a supply shock from the Cigar Lake mine flooding and China’s sovereign contracting program driving long-term prices. It still collapsed.

2/ Why Uranium is an Unusual Commodity

The single most counterintuitive fact about the uranium market is that it has, in Grant Isaac’s framing, “basically zero fundamental in-year demand.” Every reactor currently operating will load its next fuel bundle from uranium that has already been procured.

No utility anywhere on the planet is going into the market today to buy uranium it needs in the next 12 to 18 months. That material is already sitting in a warehouse, in a conversion facility, or moving through the enrichment and fabrication queue.

This inverts every intuition imported from oil markets. When oil demand rises, refiners buy more crude. When natural gas gets tight, utilities burn through spot supply and prices spike within weeks. The feedback loop between physical demand and price is immediate and visible. In uranium, that feedback loop is broken by design.

Utilities treat nuclear fuel as a long-lead procurement item. It is closer in spirit to steam generators or a reactor pressure vessel, ordered years in advance through carefully negotiated bilateral contracts, than buying natural gas. Global uranium demand currently runs around 175 million pounds per year.

What passes for a spot market amounts to roughly 50 million pounds traded per year, of which utilities account for perhaps 10 million pounds of discretionary buying: outage adjustments, inventory top-ups, opportunistic purchases when price dips.

The real market is the bilateral term contract market, negotiated out of public view, and the price it produces can only be seen in the rear-view mirror rather than a windshield. It takes a week of negotiations to surface the spot price and a month of transaction volume to establish the term price.

There is no real price discovery: no Bloomberg refresh, no live tick, no forward curve with the liquidity of an oil futures market. The uranium price is always, to some degree, a historical artifact.

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chris keefer

@Dr_Keefer

Apr 28

X-Energy's Immodest IPO: A mega thread🧵

1/ X-Energy was listed on the Nasdaq under the ticker “XE” on April 24th, raising $1.02 billion with shares surging 30.9% on debut to give the company a valuation of $11.9 billion.

The bold claim made by @xenergynuclear CEO Clay Sell in the present tense that “We make it easy to build nuclear power plants” will certainly be put to the test. Extraordinary claims require extraordinary evidence and that evidence has yet to be produced.

Lets examine what China's 50-year pebble bed high-temperature-gas-reactor program can teach us about the valuation of the West's most recent publicly traded reactor company.

2/ X-Energy's pitch is that Dow Chemical @DowNewsroom as anchor customer, @amazon as both lead equity investor and holder of power purchase commitments for more than 5 GWe, and Centrica as a UK utility partner, all anchored to an 80 MWe pebble-bed high-temperature gas-cooled reactor.

The embedded assumption in X-Energy’s $11.9 billion valuation is that American startup dynamism can compress what has been for China, the world’s most capable nuclear industrial state, a 50-year institutional journey into a single first-of-a-kind pebble bed high temperature gas reactor construction project.

In sectors where design, capital, and IP are dominant, that assumption is often correct. China’s pebble-bed program, however, illustrates why even “advanced nuclear” is not one of those industries.

3/ X-Energy is a 916-person development-stage company promising rapid construction of high reliability reactors fuelled by proprietary TRISO fuel which is roughly 10 times more expensive to fabricate than conventional light water reactor fuel. For a deep dive on that topic, see Decouple’s interview with Michael Seely below.

It has no construction experience, has never operated nuclear reactors, and is yet to produce commercial fuel. Yet it is priced as though the hardest engineering problems in one of nuclear’s least mature reactor classes are already solved.

The current AI-driven moment of nuclear euphoria creates the conditions where this is possible. In the absence of a sustained tempo of nuclear construction in the West, narratives trump empiric reality and reactor concepts that are genuinely interesting science projects get priced as commercial products well before the performance record justifies it.

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chris keefer

@Dr_Keefer

Apr 9

Nuclear Waste Reprocessing: A Mega-🧵1/20!

1/ Imagine a technology that could take the most feared byproduct of nuclear power and transform it into fuel: burning the long-lived actinides that make spent fuel a supposed million-year liability down to fission products that decay to background radiation within a few centuries.

All of this while extracting enough energy from the 95,000 metric tons of nuclear waste sitting in pools and dry casks across the United States to power the entire country for 150 years.

That technology has been demonstrated. At Idaho National Laboratory, the Experimental Breeder Reactor II (EBR-2) ran for 30 years on metallic fuel cycled through an attached electrochemical reprocessing facility, closing the loop in exactly the way the vision describes: spent fuel in, fresh fuel out, waste reduced to a centuries-scale rather than geological-scale problem.

The physics and engineering has been proven at pilot research scale. It has, however, failed to scale.

2/ What did scale commercially looks considerably different. La Hague, the world’s largest reprocessing facility, has operated for the better part of a century. France built it not out of a romantic attachment to the closed fuel cycle but out a perceived energy security necessity: Almost no domestic fossil fuels, and, in the postwar decades, uranium supply chains that looked dangerously thin.

French reprocessing works. It has extended the country’s uranium utilization, deferred the need to mine fresh uranium by putting depleted enrichment tails and recovered plutonium back to work as MOX fuel, and given Paris a degree of fuel cycle independence that looks increasingly valuable as the theme of energy security once more rises to prominence with the Iran war and the closure of the Strait of Hormuz.

What French reprocessing does not do is meaningfully reduce the volume of material destined for deep geological disposal.

But the La Hague program is not EBR-2. It is a pragmatic industrial process operating within the constraints of thermal reactor physics, and those constraints are severe.

The gap between what France actually achieves and what the closed cycle promises is the central story of nuclear reprocessing, and it begins with understanding what is actually sitting in those spent fuel pools.

3/ What Spent Fuel Actually Is

When uranium fuel completes its working life in a reactor, it leaves behind a material of remarkable complexity.

A fresh fuel assembly loaded into a pressurized water reactor contains uranium enriched to roughly 5% U-235, the fissile isotope that sustains the chain reaction, with the remaining 95% being U-238, which does not fission under thermal neutron bombardment but plays its own important role.

Over the course of 18-24 months in the reactor core, several things happen simultaneously.

The uranium-235 is progressively consumed, splitting into fission products: a zoo of mid-weight atoms, many of them intensely radioactive, which accumulate in the fuel and increasingly poison the neutron economy in the reactor.

Separately, some of the uranium-238 absorbs neutrons and transmutes into heavier elements. The most significant of these is plutonium-239, which is fissile and begins contributing meaningfully to the reactor’s power output.

By the time a fuel assembly is discharged, roughly half of the energy being generated comes from this in-situ produced plutonium rather than from the original uranium-235.

What emerges from the reactor is therefore not simply depleted uranium.

It is approximately 95% uranium, mostly uranium-238 with perhaps 1% uranium-235 remaining, around 1% plutonium spread across several isotopes of varying usefulness, and 3 to 4% fission products.

The fission products are what make spent fuel so radiologically hostile: short-lived but intensely radioactive isotopes generating substantial decay heat and penetrating gamma radiation.

The barrier to reloading the spent fuel is primarily that the fission products have made the neutronic environment unworkable and the physical handling of the fuel intolerable.

Reprocessing is, at its core, the project of separating the still-useful heavy metals from this contaminating matrix.

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chris keefer

@Dr_Keefer

Mar 24

Europe Forgot the Lesson the 1970s Oil Shocks Once Taught

The continent answered with reactors, pipeline diplomacy, and offshore drilling, then spent three decades neglecting and dismantling everything it had built. a mega🧵inspired in part by my conversation with Doomberg.

The European response to the OPEC embargo was an impressive mobilization that moved decisively and pragmatically taking advantage of the unique conditions available throughout the bloc.

France moved decisively launching the The Messmer Plan in direct response to the oil shock. It remains the fastest large-scale nuclear buildout in history.

France had little domestic oil, but it had everything else the program required: a large corps of state-trained engineers produced by the Grandes Écoles, heavy industrial capacity rebuilt under the postwar dirigiste economic model, and a nationalized utility in Électricité de France (EDF) already accustomed to executing at the direction of the state rather than waiting on market incentives.

Its political class drew the logical conclusion: electrify aggressively around a domestic nuclear base, using a standardized reactor designs that a purpose-built supply chain could replicate at pace.

Space heating, water heating, rail and significant portions of industrial process heat were shifted onto the grid as the fleet came online, deliberately substituting domestic electrons for imported hydrocarbons across as much of the economy as the technology of the era allowed.

The result over roughly twenty years was 54 operating reactors, an electricity system generating around 75 percent of its output from nuclear, net electricity exports to neighbours who had made different choices, and as an unintentional side effect a per-capita carbon footprint in the power sector that remains among the lowest in the developed world.

2/ Britain and Norway answered through a different channel with the same underlying instinct.

The North Sea had yielded promising geological discoveries before the embargo, but the post-shock period transformed offshore petroleum into a central national project on both sides of the median line.

The technical obstacles were formidable: deepwater fields in rough northern seas, novel platform engineering, supply chain development for equipment categories that had barely existed before.

Both governments pressed through, operating under a governing assumption that sounds almost exotic in Brussels today, namely that a country should develop strategically important resources under its own waters when those resources can materially improve national resilience.

Within roughly a decade Britain had moved from significant oil importer to net exporter. Combined British and Norwegian output contributed materially to the global oil supply glut that emerged through the 1980s. The glut that always follows a supply shock once investment finally responds to price signals was this time in part European.

3/ West Germany’s answer came through diplomacy and welded steel.

The first Soviet gas began flowing west through the Brotherhood pipeline in 1968, predating Ostpolitik’s formal articulation but embodying its central intuition: that a Russia earning deutschmarks from gas exports had a material interest in stable relations, and that pipelines, unlike armies, are hard to redeploy.

The 1973 embargo deepened that conviction. If imported Middle Eastern oil was vulnerable to political interruption, the answer was to secure more pipeline gas from a supplier with whom West Germany had a structured commercial relationship and a shared interest in its continuation.

The Urengoy-Pomary-Uzhgorod pipeline, completed in 1984 and running from the vast Urengoy gas field in western Siberia to the West German border, was a direct product of that post-shock logic, and it was built over fierce American objection.

The Reagan administration attempted to block European firms from supplying equipment and technology for its construction, arguing that the pipeline would create dangerous dependency. Bonn, Paris, and London essentially told Washington to mind its own business, and the pipeline was completed anyway.

What the gas bought Germany was an industrial cost structure that its European competitors could not match. German chemical producers, steel mills, glassmakers, and ceramics manufacturers built their economics around feedstock and energy costs that were simply unavailable to producers in Britain, France, or the United States.

BASF’s Ludwigshafen complex, the largest integrated chemical site in the world, was in part a monument to cheap Russian gas. Germany became the economic engine of the European Union partly on the strength of that bargain, running large industrial surpluses while its neighbors ran deficits, with cheap energy as one of the structural advantages that made German manufacturing so difficult to compete against.

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chris keefer

@Dr_Keefer

Mar 13

Ras Laffan and the Arctic Metagaz: How two drones changed the calculus of global LNG dependence

A Mega 🧵based on my @DecoupleMedia conversation with @SStapczynski

Qatar is roughly the size of Connecticut, a narrow peninsula jutting into the Persian Gulf on the wrong side of the Strait of Hormuz. For decades, this geography was considered a manageable risk, because Qatar had cultivated a reputation for perfect reliability.

When Japan shut down its reactor fleet after Fukushima in 2011 and scrambled to replace the lost generation with gas, Qatar delivered. When spot and short-term suppliers, including an Italian energy major and at least one trading house, voided their flexible contracts with Pakistan during the 2022 price spike and rerouted those cargoes to European buyers willing to pay more, Qatar delivered those too.

Then a $50,000 Iranian drone struck Ras Laffan.

The attack came in the broader wave of Iranian retaliation for the US-Israeli bombing campaign against Iranian nuclear and military infrastructure. Qatar, which had maintained som

Artic Metagaz on fire near Malte of the warmest relations with Iran of any Gulf state and had served as broker for the first Israel-Hamas ceasefire, was hit anyway.

The strike forced an evacuation of the facility and the first force majeure declaration in Ras Laffan’s history. The complex produces 77 million tonnes per year (Mt/y), roughly 19 percent of the 411 Mt traded globally in 2024. The North Field East expansion, the first of three planned phases that would nearly double Qatari capacity to 142 Mt/y by 2030, was approaching its first commissioning when the drone hit.

That same week, in the Mediterranean, a Ukranian drone boat struck the Arctic Metagaz, a Russian LNG carrier transiting toward the Suez Canal. The ship was not difficult to find. It was on a known route, visible on commercial vessel-tracking platforms, its name painted on the hull.

LNG tankers had already been rerouting around the Cape of Good Hope since the Houthi attacks made the Red Sea dangerous in late 2023, absorbing the extra transit time and cost rather than risk the strait. But no LNG carrier had been successfully struck. The Arctic Metagaz was the first. For Russia, losing one vessel from a fleet of sixteen shadow tankers is not a rounding error.

The two attacks came within days of each other, from different actors hitting different kinds of targets with different customers, but they broke the same assumption. The cascade that followed is not limited to European gas futures. It includes fertilizer plants in Pakistan going dark, rice farmers in Thailand who cannot get diesel, and nine days of reserve supply sitting in South Korean LNG storage tanks.

The Champagne of Fuels

To understand why the disruption hit so asymmetrically, it helps to understand what LNG actually is and why its supply chain concentrates risk the way it does. Natural gas, cooled to roughly minus 162 degrees Celsius, compresses to about one six-hundredth of its original volume, dense enough to ship economically across oceans.

That compression is the whole business: the liquefaction trains at Ras Laffan are the refrigerators, enormous industrial machines that chill gas into liquid and run continuously, taking weeks to months to restart after a cold shutdown; purpose-built cryogenic tankers are the thermoses, keeping cargo at minus 162 degrees Celsius across thousands of miles of open ocean; and the regasification terminals in Japan, South Korea, and Pakistan are the toasters that warm it back into pipeline-ready gas.

In a previous episode with Stephen we called LNG the champagne of fuels, and the analogy holds: it is expensive to produce, requires extraordinary handling at every stage, and arrives at the table only because an elaborate and costly infrastructure exists to get it there without incident.

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