Millions of Americans are sweltering under heat domes this summer, with temperatures soaring to record highs when weather systems stall. The grid feels the strain of these events too.

This extreme heat often creates a precarious situation that pushes electricity demand to levels never seen before, while forcing generation out of service. But why does summer weather get stuck like this in the first place? And is climate change making it happen more often?

For answers we can look to the North Atlantic jet stream, the high-altitude wind steering weather across North America and Europe. Our guest visualizes this as a ski-slope, where a steep gradient between temperatures keeps the jet racing fast and weather moving. Though, as the Arctic warms faster than the rest of the planet, the slope flattens, slowing the jet stream, which has it meandering in bigger waves. Slow weather becomes stuck weather. Whatever comes along, heat, rain, or drought, can then sit around for longer. Our host Chris Nelder dug into this mechanism in Episode #65, the ninth part of our climate science miniseries. That was back in 2018, years before “heat dome” became a household phrase.

In this conversation, recorded February 2018, Valerie Trouet, of the University of Arizona’s Laboratory of Tree-Ring Research, explains how she reconstructed the jet’s summer position back to 1725 from the density of tree rings in the British Isles and the Balkans. As the planet warmed, the jet lunged north and south far more often. Jet stream excursions like this have increased sharply since the 1960s, looking nothing like the natural climate variability of the three-century record.

Valerie Trouet shares with us how a five-millimeter core from a living tree reveals the climate’s history. She also covers why the jet’s slowdown makes more of an impact than how far it swings. Valerie’s lab has continued publishing on this topic, and in a 2024 paper in Nature, her group took the reconstruction back to 1300 CE, reading jet behavior in seven hundred years of European harvest dates, grain markets, and mortality. Her former postdoc went even longer in a 2025 study tracing hemisphere-wide jet patterns across a full millennium, and so far, their frequency looks essentially unchanged on that extended timescale. Today’s episode is one of our lagniappe releases, so the complete original conversation can be freely available for the entire Energy Transition Show audience.

The Statistical Review of World Energy 2026 is out, offering the first complete look at global energy data for 2025. The report’s 75th edition, now presented in partnership with the energy think tank Ember, reveals a year in which demand for every form of energy hit a new record high.

But growing overall demand, even for fossil fuels, doesn’t mean the energy transition isn’t happening. Renewables grew more than any other form of energy for the first time outside of a recession, with solar power accounting for 72% of the increase. And global electrification reached a tipping point, with electricity demand growing 3%, faster than energy supply overall. China alone added the equivalent of Germany’s entire annual electricity consumption in a single year. These are just a few of the indications that the future of global energy use is increasingly electric, even as regional paths differ.

In 2025, rising electricity demand was met entirely by low-carbon sources, with renewables and hydro overtaking coal as the largest source of generation. Fossil generation fell overall, demonstrating that fossil fuels are being substituted rather than supplemented.

Solar and storage are clearly taking the lead in the global energy system, and they’re not looking back, as global battery storage capacity grew 66% last year alone. Solar already produces more electricity than gas in major parts of the world, and its lead in power generation will only grow.

In this episode, we are joined by Aditya Lolla, Interim Managing Director at Ember, and Euan Graham, Senior Electricity and Data Analyst at Ember and a lead author of the report, to share the key findings from this new update on all the energy data that matters.

We’ll dig into the report’s new total energy supply measure, which we explored in Episode #259. We’ll hear how China’s road fuel demand is now falling, redefining the assumed long tai

Right now, Great Britain has more than enough new solar projects waiting to be connected to its distribution grid to meet its 2030 renewable energy target.

Italy and Poland could reach half their 2030 solar targets just by connecting the solar already sitting in their queues.

Across just eight European countries, there’s a whopping 375 GW of wind and solar PV projects, and an even larger 455 GW of battery storage projects, just languishing in connection queues. Together, these wind, solar and battery resources are roughly equivalent to the entire generation capacity of those countries.

These are the shocking findings from a new study commissioned by the European climate nonprofit Beyond Fossil Fuels. Its estimates are deliberately conservative: the study values the trapped clean energy projects at around €100 billion, with the real total almost certainly higher. In this episode, we welcome Tara Connolly, their Programme Lead for Energy Markets and Grids, to share what the report found and learn what can be done about this sad state of affairs.

And the crunch isn’t only on the supply side. Data centers are now muscling to the front of the same queues. In Ireland, they already consume half of greater Dublin’s electricity, while households’ EV chargers, rooftop solar, and home batteries wait behind them.

It will not surprise our longtime listeners at all to learn that unlocking all this mostly comes down to regulation, with many of the fixes already on the books, just not enforced.

It’s taken a very long time to arrive, but next-generation geothermal power is finally becoming a commercial technology. Even though the virtues of geothermal have long been known and appreciated as clean, low-impact, and capable of running continuously, the few conventional geothermal installations in the US operating for decades supply less than half a percent of the nation’s electricity. The promise of next-generation, “enhanced” geothermal, which we discussed back in Episode #248, is that it can be used almost anywhere. But business and technical challenges have held it back.

Until recently, that is. Now, several companies have overcome those challenges and are hard at work on new projects in the US and elsewhere, including Fervo Energy’s Cape Station project in Utah, which is expected to begin delivering power this year and expand to 500 MW by 2028.

And the resource is significant: According to the IEA, the technical potential for next-generation geothermal wells less than 5 km deep in the United States is greater than 7 terawatts, a number that’s more than five times the nation’s total existing electricity generation capacity. The US Department of Energy projects that as much as 300 GW of that could be economically deployed by 2050, enough to meet up to 40 percent of anticipated demand growth. Some studies suggest that if new data centers are sited strategically, geothermal could power all of them. And costs are coming down fast. The IEA estimates they could fall by as much as 80 percent, which would make geothermal cost-competitive across the US. All that development would also create or preserve hundreds of thousands of jobs, many using skills that transfer directly from oil and gas extraction and fossil power generation.

To lay out the opportunity, the obstacles, and the state of the art in enhanced geothermal, we are pleased to be joined by Dr. Emily Pope, a senior fellow at the Center for Climate and Energy Solutions. Her report, Drilling Down—What it Will Take to Harness the Potential of Next-Generation Geothermal, was published in April and offers a comprehensive review of the sector. So if you gave up on geothermal years ago, this episode will show you what’s changed.

This is the third and final part of our miniseries about South Africa’s energy transition, based on Chris’ travels there in September and October of 2025. The first part was Episode #264, in which we heard how the end of apartheid precipitated reform of the country’s energy systems. The second part was Episode #276, where we learned how South Africa is reforming its electricity system from a state-owned monopoly to a free market, and from coal to renewables.

South Africa has enough wind and solar resources and land to generate at least three times as much power as its entire annual load, but the country is still locked into its old coal-fired electricity grid. Market reform is the key to unlocking that potential.

In this episode, we’ll hear how those reforms can help deliver a just transition for South Africa, the most economically unequal country in the world. Because there, the energy transition isn’t only about cheap, clean power; it’s also a driver of economic justice. Today, some of the poorest households pay up to three times the grid price for electricity drawn through informal connections, and formalizing that power is a chance to deliver cheaper, fairer access to those who need it most.

We’ll also learn how utilities and regulators across sub-Saharan Africa are working to integrate unsanctioned, distributed solar and storage into their grids. In South Africa, roughly 60% of those systems were never reported to the utility, and in Kenya the figure is effectively 100%. The economics are hard to argue with: the $1.7 billion Africa spent on solar panels last year is already meeting more demand than the $20 billion a year it spends on diesel fuel, with more than 85% of it self-financed. That bottom-up adoption is now transforming energy systems not only in South Africa, but across the entire region.

This is the second part of a miniseries about South Africa’s energy transition, based on Chris’ travels there in September and October of 2025. The first part was Episode 264, in which we heard how the end of apartheid precipitated reform of the country’s energy systems.

South Africa is arguably one of the most exciting places in the world to see the energy transition unfolding right now, because after nearly 150 years of relying almost exclusively on coal for its energy, it is finally implementing reforms that will allow its electricity system to integrate more renewables onto its grid.

Eskom, the state-owned monopoly, has owned and controlled the grid for over a century. Its aging coal fleet still provides around 80 percent of the country’s electricity, even though solar power is now far cheaper, and it has been able to block new renewable projects because they threatened its coal business. But now Eskom is being broken up into separate units for generation, transmission, and distribution. And the country is launching its first wholesale electricity market — the South Africa Wholesale Electricity Market, or SAWEM — opening the door for renewables to compete with coal.

At the same time, there is also an enormous and growing informal supply in the form of distributed solar — enough to meet a quarter of the country’s electricity demand. Many businesses and residents are installing their own solar and battery systems, often without any kind of permission from or notice to the utility. That is simultaneously creating an entirely new and complex sort of electricity system that’s hard for utilities to manage, while also making the system far more resilient. In fact, distributed solar batteries are credited with putting an end to the “load shedding” blackouts that plagued customers for over 15 years.

Formally and informally, South Africa is rushing headlong from its coal-fired past and into the renewably powered future. Clean generation led by solar surged past 30 percent in late 2025, while coal fell to a record monthly low. South Africa’s experiment in restructuring a vertically integrated, coal-dependent grid offers an early look at the politics, economics, and surprises that other markets will face as they take on their own transitions to renewables.

In this episode, we’ll be hearing from experts who are closely involved with the electricity reforms in South Africa. In the next episode, we’ll see how those reforms play an important role in delivering a just transition.

In mid-2026 we’re experiencing the largest energy crisis the world has ever faced. The sudden and prolonged disappearance of one-fifth of the global supply of oil and LNG, set in motion by the Iran war we covered in Episode #272, has sent import costs soaring. World leaders are now confronting the risks of fossil fuel dependence as never before.

The high costs and outright physical shortages of oil and gas are driving inflation across the global economy. But that’s not all. The crisis is also weakening currencies in importing economies, deepening their debt, stalling growth, and transferring wealth on an enormous scale. By 350.org‘s count, more than $150 billion has already moved from ordinary households into the balance sheets of oil and gas companies.

A new report from 350.org, Out of Pocket: How Delaying Global Fossil Fuel Phase Out is Draining Households and Economies, puts hard numbers on the price of delaying the energy transition. In today’s conversation, we welcome the lead author, Clémence Dubois, Global Campaign Manager at 350.org, to share its findings. Clémence explains how the delay imposes opportunity costs, economic and environmental justice costs, and national security risks on importing countries. She makes the case for why this crisis, unlike the six previous oil shocks, might be the final nail in the coffin of the world’s dependence on imported oil and gas. And we’ll see how many countries are already switching to domestic renewables and electrification — because for them, delay is no longer an option.

For years, transition skeptics have argued that what’s really happening globally is “energy addition,” where renewables are piling on top of fossil fuels rather than pushing them aside. The data that’s just landing from 2025 finally puts that argument to rest.

For the first time, global electricity generation from fossil fuels fell, not because of a pandemic shutdown, recession, or unusual weather, but simply because renewables grew faster than demand. Power-sector emissions dropped along with it, also a first. Solar recorded the largest single-year increase of any electricity source on record, with the exception of coal’s rebound as the world re-opened after 2020. And renewable generation surpassed coal in the modern era for the first time.

These are just a few of the important findings in Ember’s Global Electricity Review 2026. To unpack what they mean, and what they don’t, we welcome back to the program Nicolas Fulghum, Senior Energy and Climate Data Analyst at Ember and one of the report’s lead authors. Nic was last on the show in Episode #254 reviewing the 2025 edition of this report, which became our most popular episode of the year, and which we re-released without paywall in Episode #266.

In today’s show, we’ll see how the structural decline in fossil generation, long-anticipated by transitionistas, finally arrived. We’ll hear why solar’s growth rate refuses to slow even as the technology matures. And we’ll explore how the second fossil fuel shock of the decade, this time from the Iran war we covered in Episode #272, is pushing more countries to accelerate their move off imported fuels. The energy transition isn’t coming. It’s here, and it’s getting more unstoppable every year.

In the sunniest parts of the world, solar and batteries are already the cheapest way to build new power generation capacity on an unsubsidized full system cost basis, and that cost advantage is expanding quickly.

By the end of this decade, solar and batteries could affordably supply 90% of electricity for most of the world’s population at less than €80/MWh—that’s a full system cost, including fuel-based backup, for about US 8.7¢/kWh. While this is already cheaper than building a new gas-fired grid, given that European gas prices spiked to ten times their normal level during the 2022 energy crisis and remain volatile today, the gap is only likely to widen.

But beyond 2030—well within the lifetime of any new power generation system built today—solar and batteries will almost certainly be the cheapest, most reliable, and least volatile way to expand a power grid. Doubling down on fossil gas generation under these conditions, as many governments are contemplating, would be a terrible mistake, both economically and geopolitically.

That is the central finding of a model developed by Tom Brown, professor for Digital Transformation in Energy Systems at the Technical University of Berlin. Tom also led the development of the open-source toolbox Python for Power System Analysis (PyPSA), and based this analysis on a blog post titled “Solar and batteries can power the world.” If you doubt the conclusions, you can run the model and test the assumptions yourself.

In today’s episode, we’ll dig into how the model works, what happens when you add wind to the mix, and why battery costs could halve again by 2050, making solar-dominated grids dramatically cheaper than anything we can build with gas. We’ll also examine the land question and find that powering the world with solar would take just 0.3% of global land, a fraction of what we currently devote to livestock. And we’ll revisit how to meet that last 10% of demand, a topic we last explored in Episode #188 with Paul Denholm of NREL, and hear Tom’s case for methanol as a surprisingly practical backup fuel.

The attacks on Iran by US and Israel have touched off a regional conflict that has resulted in the closure of the Strait of Hormuz, through which 20% of the world’s oil and LNG transits, and is doing severe, ongoing damage to oil and gas infrastructure throughout the Persian Gulf. We are now in a new global energy crisis.

IEA coordinated the largest release ever of oil from strategic reserves to calm the oil market, but traders shrugged it off and oil prices kept climbing, because a physical disruption at this scale is totally unprecedented. Even so, veteran oil traders and journalists have warned that the world is still not recognizing the depth of the actual peril it’s in. IEA Executive Director Fatih Birol called this crisis “the greatest global energy security threat in history” and said, “I believe the world has not yet well understood the depth of the energy security challenge we are facing.” IEA also admonished governments to take steps to conserve fuel, including urging their citizens to drive more slowly, work from home, take public transport and car sharing, avoid air travel, and switch to electric cooking. The last time IEA called for such wide-ranging demand reduction was in the 1973 Arab Oil Embargo.

The consequences are already cascading well beyond oil: Fertilizer prices have surged 25 to 40 percent, and a similar increase in the price of diesel will flow through to essentially everything, causing “fossilflation.” In response, governments across Asia have begun curbing consumption: Bangladesh is shutting universities early to save power, Thailand and Vietnam are pushing civil servants to work from home, and Myanmar has imposed fuel rationing. And that’s just the beginning.

To help us understand this rapidly-worsening reality, we are joined by Rory Johnston, one of the most widely cited independent oil market analysts, founder of the Commodity Context newsletter, and host of the Oil Ground Up podcast. Johnston, who typically avoids alarmist price calls, says $200 a barrel minimum is now on the table. We discuss why the world’s emergency supply tools aren’t working, where oil prices could go from here, and why this crisis has thrown the world into uncharted territory.

It could take the world years to recover from this…but in that interim, it’s likely to accelerate the energy transition.

To help everyone cut through the fog of war and disinformation, and understand what is happening and how it will affect them, we are publishing this episode without a paywall. So please share it widely.