On this podcast, we spend a lot of time talking about electricity — how to generate it, store it, and use less of it. But the truth is, the bigger share of our energy use often goes to heating and cooling — the invisible comfort systems that keep us alive in the places we choose to live. Humans are unusual that way. Most species adapt to their environment. We do the opposite — we adapt the environment to suit us. It's how we survive in deserts and tundra, in glass towers and remote villages. Today on the show, we're talking about passive cooling. We bring you three stories of designs that take advantage of natural temperature differences instead of using up a bunch of energy just to make something cold. Closing the Gap is hosted by Gwen Holdmann. Tony Williams is our producer and engineer. Jennifer Pemberton is our writer and editor. Music is from Blue Dot Sessions.
Waste-to-energy systems kill two birds with one stone: they deal with garbage and produce power at the same time. Copenhill in Denmark has been called the coolest power plant in the world, and it's hard to argue with that. It's a place where you can ski down the roof, climb up the side, and then grab coffee under the smokestack — all while the building generates heat and energy for the city. At least one Alaskan community thinks Copenhagen might hold the answer for its energy and waste problems — and that's exactly where this episode takes us.
The multi-million dollar fighter jets that roar over the local tennis court where I coach the high school team is a daily reminder that Fairbanks is home to one of the most strategically important Air Force bases in the world. And now, Eielson Air Force Base is about to make history on a very different front — testing a first-of-its-kind nuclear microreactor. Closing the Gap is hosted by Gwen Holdmann, edited by Jennifer Pemberton, and produced by Tony Williams.
Back in 2019, Congress directed the Department of Defense to find a site and pilot a small nuclear reactor to enhance energy resilience at military installations. That site is Eielson Air Force Base near Fairbanks, Alaska. Recently the Air Force named a developer for the reactor, so we're revisiting the story we told back in Episode 5. In future episodes you'll hear directly from the key people moving the project forward—both the technical lead for the Air Force and the senior commander guiding its integration on the ground. For now, we're sharing episode 5 with you as a refresher.
Water is 800 times denser than air and when large volumes start moving in a single direction with force and purpose, it becomes virtually unstoppable—whether at sea or on land. And that force represents an opportunity—to harness the power of water in a way that's different from conventional hydropower. Instead of relying on elevation and gravity, we can capture energy directly from the flow itself. Afterall, the tides are pulled by the moon, creating a rhythm that has been in motion since long before fossil fuels were even imaginable. It's not just renewable—it's perpetual. Today on the show -- tidal energy in many different forms. Closing the Gap is hosted by Gwen Holdmann. Jennifer Pemberton is our editor. Liz Smith and Tony Williams produced this episode. Music is from Bluedot Sessions. Special thanks to David Lane at Neuralsurfer, who let us use his wonderful recording of Edgar Allen Poe's "A Descent Into The Maelstrom".
Hydropower comes in many forms, though most people still associate it with big dams. In the heyday of dam building, projects like Grand Coulee Dam and Boulder Dam in the American West were monumental efforts. These were some of the most ambitious and costly construction projects ever undertaken. Back then, we didn't fully understand how dams could disrupt ecosystems—blocking fish passage, altering sediment flow, and changing entire river systems. But now we do, and as a result, large dams have fallen out of favor in many places. And where the U.S. was once the leader in large scale hydropower, we're now removing more dams than we're building. Today, the biggest obstacles to constructing new hydroelectric projects in the U.S. aren't just environmental—they're economic and regulatory. Escalating construction costs and complex permitting processes have significantly slowed the pace of development. But hydropower is a very site-specific technology—and there are plenty of ways to make it more environmentally friendly. In Alaska, for example, we have dozens of what are called "run-of-river" hydro systems. These projects harness the natural flow of water to generate electricity, often without the need for large dams or reservoirs—and without blocking fish passage, which is a big deal in a state where salmon are central to both ecosystems and communities. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Tony Williams. Music is from Blue Dot Sessions.
We started our series on solar energy at a small scale. This time, we are going big. The Al Kharsaah Solar Plant in Qatar is one of the largest solar farms in the world—capable, at least in theory, of producing enough power to meet the entire demand of the Railbelt electrical grid in Alaska, which serves about half a million residents. But even though Al Kharsaah is large, it's far from the largest. When Gwen was there last year, it was in the top 20 largest projects in the world. Today, it doesn't even make the top 30 anymore. In this episode, we're going to take a closer look at solar at scale—exploring the limits to scaling up this seemingly unlimited energy source, and the innovations underway today that could define what the solar industry looks like in the future - both in solar photovoltaics like in Qatar, as well as concentrating solar thermal. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Liz Smith and Tony Williams. Music is from Blue Dot Sessions.
This is the first episode in a series about solar energy, and we're starting really small. In Germany, Gwen learned about these compact personal solar kits you can install yourself -- right out of the box. There, they call it balkonkraftwerk, or balcony solar. Of course she had to buy one when she got back from Europe and try it out on her roof in Fairbanks. But is the grid ready for this kind of DIY power generation? Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Liz Smith. Music is from Blue Dot Sessions.
You don't need super high temperatures to harness geothermal energy. Under the right circumstances, a much smaller thermal gradient can be used as well. If we start digging, we're guaranteed to find heat. It's getting that heat to the surface where we can use it without spending more energy than we can actually get out of it -- that's the tricky part. We visit South Africa, Denmark, and upstate New York to learn about the not-so-hot geothermal resource that's beneath our feet all over the world. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Liz Smith. Music is from Blue Dot Sessions.
A look at the extreme edges of geothermal energy. We'll start with the super hot -- actual liquid magma -- chatting with a couple of visionary Icelanders that have some big ideas about the future of geothermal. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Tony Williams. Music is from Blue Dot Sessions.
We cover the basics of geothermal energy before diving in to the more extreme versions of the technology in the next few episodes. And where better to kick off an episode on geothermal than with a mini-tour of Iceland — a country that has arguably made better use of geothermal than anywhere else on earth? In this episode, we'll visit three sites in the southwest near the capital of Reykjavik before winding up in my own backyard in Alaska. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Tony Williams. Music is from Blue Dot Sessions.
Before our towns and homes were lit by electricity, we relied on something called town gas for everything from reading lights to cooking. Eventually, town gas in most places was replaced by natural gas, which burned cleaner. But the switch from town gas to natural gas was not a one to one replacement, and it was not trivial. Because town gas, unlike natural gas, is mostly hydrogen. Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
Hydrogen is the most abundant element in the universe and is the energy source powering our sun. The idea of a hydrogen economy has been promoted for decades. So what's holding us back? Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
We explore two carbon capture technologies that are exploiting natural geologic processes. But the companies working on these solutions are taking those natural processes and speeding them up a bit -- giving mother nature a little extra push in order to try and slow down climate change.
Not every place has the right geologic settings for long-term carbon storage. But Alaska is one – in fact, Cook Inlet is the best tidewater location for storage on the entire west coast of North America. North Dakota is another. And for North Dakota this isn't necessarily so much about mitigating climate change, it's about building a new niche market to offer a service that others are willing to pay them for.
Like much of rural Alaska, the town of Nome relies heavily on imported fuels for heating and power. The cost of heating oil here is well over $7/gallon. That's what incentivizes a lot of Alaska communities to pursue new energy technologies, often well before they are part of the mainstream. Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
The U.S. Nuclear Regulatory Commission expects to receive 25 licensing applications in the next five years for a new generation of advanced reactors. But getting any of these designs from the drawing board to reality is going to require overcoming a lot of hurdles and uncertainties. Getting any new technology to market is challenging, but that challenge is even more acute for nuclear because of the complexities and costs that it entails. In this episode we'll look at how two U.S. nuclear projects are navigating a complicated government licensing process to develop a first-of-its-kind technology that could make a pretty big difference in our ability to decarbonize our global energy supply. Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
Nuclear power is different from other energy sources. When we talk about new nuclear projects, it can still bring up strong and sometimes emotional reactions for people -- more so than with other sources of energy, and those opinions are much more divided across the political spectrum than any other technology. How did public perception change as nuclear moved from a technology of war to the energy solution of the future? And when it comes to energy technologies, or really any technology, how safe is safe enough? Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
Iceland is a powerhouse when it comes to harnessing the heat and the energy that's pouring up through the tectonic crack that runs diagonally across the island. Icelanders originally got the idea for geothermal district heating from turn-of-the-century Idaho. But since then, the small nation managed to gather best practices from places like Boise, and then improve on them. And now they have the most concentrated know-how of geothermal energy in the world, and they market and export that expertise globally. Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.
Iceland is widely regarded as a global leader in clean energy. Not only is their energy sustainable, it's cheap, too. They have some of the most affordable heat and power in the world. But it was literally one of the poorest countries in Europe two generations ago. So, how did Iceland get here? What would they say are the most important choices and investments they made along the way? They share their secret recipe with us on this episode of Closing the Gap. Closing the Gap is hosted by Gwen Holdmann and produced by Jennifer Pemberton. Music is from Blue Dot Sessions.