Meet the GoSun Oven, the Solar-Powered Oven of the Future

Patrick Sherwin was a solar installer in Ohio who one day, about ten years ago, took a job removing a water heater from a client’s roof. Solar water heaters, employing roughly the same technology as a Thermos, use a double-walled glass tube to collect and retain sunlight. The vacuum formed between the two walls prevents heat from dissipating. Rather than throw the tubes away, Sherwin took them home and left them in his backyard on a couple of sawhorses. He was a tinkerer; maybe he could find some or other use for these.

Later on he stuck a finger into the center of a tube and was struck by how much heat had been generated in it, simply by virtue of its being in the sun. Inspired, Sherwin got some hot dogs from the refrigerator. “Literally in ten minutes you could hear them sizzle,” he said. Improvising, he used a wire hanger to harvest his lunch. “OK, I’ve got a killer hot dog cooker here,” he thought. “Now what?”

I’ve got a killer hot dog cooker here. Now what?

The history of invention is rife with dumb luck, of course, but the birth of Sherwin’s killer hot dog cooker conspicuously recalls the origins of the microwave. That machine was invented at Raytheon, a military contractor, in the wake of the Second World War. The story goes that an engineer named Percy Spencer stood close to a magnetron, a radiation-emitting device used for radar navigation, and noticed that the candy bar in his shirt pocket had melted. Next he tried popcorn. Then an egg, which exploded on a colleague’s face. Two years later, the microwave technology he pioneered was being used in a device called the Speedy Weeny, which automatically cooked and dispensed hot dogs at Grand Central Terminal. Apparently the history of invention is also rife with wieners.

The microwave—invented in 1945, ubiquitous by the 1980s—remains the last great technological innovation to be widely adopted in American cooking. Unlike, say, the telephone, the kitchen is not much changed from what it looked like a half century ago. Neither is the language that governs what we do in it. The descriptions, numbers, labels, and expected outcomes of the home kitchen assume everybody’s working with the same equipment: the same oven (preheat to 350), stove (set over a medium flame), cookware (cover the pot and let rest ten minutes). It’s hard to think about what it would look like if any of this changed. A dramatic development in the technology might occasion—might require—a new language, a new routine, a new common cookbook.

Just getting better is not good enough. We have to figure out a way to get rid of carbon in our lives.

Is there any reason to think one is needed?

Last month Patrick Sherwin traveled to the Consumer Electronics Show, in Las Vegas, to make just such an argument. At CES, his glorified hot dog sizzler—now marketed, under the name GoSun, as a full-service solar cooker—caught the eye of publications including TechCrunch, which invited Sherwin to compete in its Hardware Battlefield. Sherwin took the stage and, introducing the GoSun, alluded to the recent climate talks in Paris. “Just getting better is not good enough,” Sherwin said. “We have to figure out a way to get rid of carbon in our lives.” (The prize ultimately went to a device that tests meals for the presence of gluten.)

The GoSun solar oven. Beautiful scenery not included.

Photo courtesy of GoSun

Solar cookers are nothing new, but so far they’ve gained the most purchase in the developing world, where they’ve offered the promise, with middling results, of clean, electricity-free food preparation. In the U.S., they’ve been popular mostly with outdoors types, people preparing to climb Peak Whatever, or, as Sherwin respectfully refers to them, “the tree-hugging community and the emergency-preparedness community.” He’s ardently aiming his product, though, at the mainstream. Part of the GoSun line is that it’s the next step forward in fuel-free cooking: an oven for the Anthropocene epoch, here to erase the kitchen’s carbon footprint.

What kind of carbon footprint does the kitchen make? Sherwin made an anecdotal case last month when I visited the GoSun offices, which fill in a painted-brick house in Spring Grove Village, a pretty, residential neighborhood on the north side of Cincinnati. Sherwin began by renting one bedroom, then two; with about a dozen employees, his business now takes up the whole building, and he expects he’ll need to find bigger digs this year. Sherwin gestured toward the house’s very traditional kitchen—specifically the toaster oven.

Put your hand over the toaster oven while it’s cooking something, he suggested. It’s a great heating device—of its surrounding area as well as what’s inside. “It’s like the old incandescent bulb: 90 percent heater, 10 percent lightbulb,” Sherwin said. In truth, many cooking devices are as casually inefficient: the uncovered pot set to boil on the stove, for instance, or the oven set for an hour at 400 degrees just to bake two potatoes. A 2010 research review in the journal Food Policy, describing kitchen energy requirements, is a trove of facts illuminating the kind of blithe energy waste going on in modern kitchens: An unlidded pot, for instance, has something like eight times the energy requirements of one with a lid. An Oxfam report estimated that if urban households in a handful of countries adjusted only slightly the way they cooked vegetables—covering the pan, reducing heat when the water starts boiling, etc—the yearly energy savings could reach 30 million megawatt hours per year, or the equivalent of planting 540 million trees.

All told, food preparation represents about 16 percent of total consumer energy consumption in the U.S. This covers the gamut of the production chain—from farm to fork, if you will. The link in this chain that’s gotten the most attention is the “food mile”—the notion that gobs of energy are expended hauling, for instance, Idaho potatoes to the corner market in Miami Beach. But the idea has perhaps been a bit overplayed. When it first became popular, “there was an assumption that local food would mean lower greenhouse gas emissions,” said Rich Pirog, the director of Michigan State University’s Center for Regional Food Systems. “When you look at the whole system, that’s not necessarily the case.”

Four million people worldwide, mostly in India, China, and parts of Africa, die each year from diseases related to smoke inhalation from wood-fired cooking

Taking economies of scale into account, for instance (and setting aside the various other virtues of eating local), transporting tons of vegetables cross-country by truck can be less resource-intensive than, say, driving an SUV to the farmers’ market for a bag of lettuce. “The public thinks that trucks consume a lot of energy, and that’s not the case,” said Ruben Morawicki, who coauthored the Food Policy paper. “In general, when you increase the scale, you become more efficient.” Better to think about food and energy consumption in terms of what researchers call a life cycle assessment: taking a measure of what’s needed to produce an item of food from start to finish, from the soil it’s grown in to the heat required to render it edible.

Compared to food miles, the conversation about resource consumption in the kitchen has remained pretty modest. Maybe that’s because cooking, as opposed to shipping, is a highly individualized, idiosyncratic process: How do you cook your rice? Do you boil it (lid off) or steam it (lid on)? Is the pan dented? Gas burner or electric? What’s the temperature of the room? Every answer has implications. And maybe it’s because, as a preponderance of people I spoke with for this story pointed out, energy in the United States is cheap. For many people, there’s little incentive to think very hard about what goes on in the kitchen.

Patrick Sherwin is, nonetheless, thinking about it.

In the ten years since Sherwin began cooking hot dogs in it, the GoSun has evolved, really, very little: The primary technology is still the evacuated tube, so called because the space between its double walls has been evacuated of air; the outside of the inner layer is coated with aluminum nitrile, a highly absorbent metallic paint. A reflector concentrates sunlight. The food cooks on a stainless-steel tray that slides in and out. It looks prettier, Sherwin said, thanks to Matt Gillespie, his lead designer: “He basically made what was a high-performance, ugly solar cooker into a high-performance, gorgeous brand.”

It’s true the thing is sleek, shiny: very space-age. Also like a Thermos, the GoSun can be scorchingly hot inside (upwards of 600 degrees on the smaller model) but completely cool to the touch outside. When the invention was still in its hot-dog-cooking phase Sherwin would bring it to public events and show it off. (It was six feet long then; Sherwin hadn’t yet realized shorter tubes were available.)

“Is that what you took to Bonnaroo?” asked Gillespie, who is young, bearded, and smiles when he talks. We were sitting in a sunny spot around a conference table in GoSun’s Cincinnati headquarters; over the windowsill, wisps of steam rose from a couple solar cookers set up on the patio. Squirrels ran around the yard. The day was icy but cloudless—mixed conditions for solar cooking.

GoSun founder Patrick Sherwin

Photo Courtesy of GoSun

“Yeah!” Sherwin said. “It was like, dang, what do I do with these six-foot tubes and hot dogs?”

The answer was to shorten it (it’s now two feet long), pretty it up, and create an argument for it. Oh, and a Kickstarter. And a social mission: GoSun is a member of the Global Alliance for Clean Cookstoves, a subset of the United Nations Foundation, which exists to find and promote in the developing world alternatives to the wood fires and rudimentary stoves that are currently prevalent.

The implications of this are stark. Four million people worldwide, mostly in India, China, and parts of Africa, die each year from diseases related to smoke inhalation from wood-fired cooking: lung cancer, cardiovascular disease. “From the health perspective, the number of deaths is staggering,” Radha Muthiah, the alliance’s CEO, told me. The carbon produced by burning wood is a significant contributor to global warming, and demand for the wood itself contributes to deforestation; moreover, it’s often women and girls trekking into the forest to collect the fuel, putting themselves in danger of violence and expending significant amounts of time that might be spent otherwise—school, for instance. The alliance has a goal to place cleaner cookstoves in 100 million homes by 2020; Muthiah says she expects to hit that number sooner.

We’ve tried burning food. It's challenging.

Solar, Muthiah said, “is one of the cleanest fuels we have available. It doesn’t cost anything.” With a grant from the alliance, in 2014, GoSun loaned solar cookers out to 40 families in Guatemala as part of a pilot program to gauge the popularity of cleaner cooking technologies. Sherwin and Gillespie said that the families decreased the time they spent in the preparation of food by about two hours a day, and at the end of the pilot, half opted to buy their stoves with the help of a microcredit. Sherwin sees such global work as central to GoSun’s mission, and is working on devising a low-cost cooker for distribution in the developing world.

In the U.S. he offers, primarily, two products. The flagship is the GoSun Sport, advertised as being able to cook a meal for two (it sells for $279). And this summer, Sherwin will launch the GoSun Grill, a larger version that can hold a meal for eight or, in less abstract terms, two whole chickens at a time (preorders available for $599). It will come with a couple new bells and whistles, including an electric heating element and the ability to plug it into an outlet, in case the sun goes down before dinner’s done.

How does the GoSun cook? Well, it definitely needs sun. The GoSun works best between 9am and 3pm, when the sun is shining brightest. And while it retains enough heat to finish cooking something you start in the afternoon, you can't start cooking at night. The GoSun works outdoors and indoors (as long as it's next to a window), but it won't work anywhere if it's cloudy out.

And it's not much like a stove or an oven, really, though it combines some capabilities of both: it can bake cookies as well as boil rice. But forget about getting a good char on anything. The device is so effective at retaining moisture, in fact, that if you’re roasting meat, you might like to drain the juices a couple times during cooking—they’ve got nowhere else to go. “We’ve tried burning food,” Gillespie said. “And you can do it, but it is a bit challenging.” Potatoes left too long in the GoSun will, rather than burn, simply break down—mash themselves, in essence. Gillespie likes it for fish and vegetables, Sherwin for bread and eggs. He showed me pictures on his iPhone of recent successes: A piece of salmon. Quiche. Pumpkin spice cookies. It’s especially good, Gillespie noted, for tamales.

For 350,000 years we’ve been taking pots and putting them on top of fire. Now we’re trying convince people there's another easy, viable way to make dinner.

For the forthcoming grill, Sherwin abandoned the notion of including a traditional temperature gauge—what does 350 degrees mean in such a radically different cooking environment?—and, when we talked, was leaning toward indicating the internal heat on a scale of one to ten. With customers, he said, “we’ll have a conversation around, what kind of temperature were you at? Well, I was between a two and a four. How hot is that? It cooked the bread in 37 minutes—that’s how hot it was.”

You can see how some traditional recipes, with their pedantic temperature requirements and their expected cook times, might not completely translate to this device. On the other hand, other recipes may be optimized for it. In an article on the website TreeHugger, the environmental writer Lloyd Alter pointed out that the device would be great for cooking Chinese, “a cuisine where everything was chopped into small pieces because fuel was scarce and expensive, and small pieces tossed in a wok cook very quickly and use very little fuel.”

“Instead of a big solar oven that adapts to our conventional idea of cooking,” Alter wrote, “the GoSun requires a bit of adaptation of our diet.”

Sherwin and Gillespie readily, and refreshingly, endorse this notion, making no promises the GoSun will do everything home cooks are used to an oven (or stove) doing. Rather, they suggest that a rethinking of the regime is in order. “Things don't really seem like a problem until there’s another route,” Gillespie said. "Like cars, for example. They’re death traps. They take our money. They take our time. And yet we use [them] every day. Now if we had a better alternative, like autonomous or electric cars, then it would suddenly change the debate. And that’s what we’re hoping is going to happen. Ultimately, we’ll frame the problem of clean cooking a little differently, and help people realize there are real alternatives.”

“The challenge we have is simply convincing people that it's a great way to cook,” Sherwin said. “For 350,000 years we’ve been taking pots and putting them on top of fire, so all our cooking pots are cauldron-based. And here we’re trying to take a pot on its side, longways, and convince others that that is an easy, viable way to get their dinner.”

So far Sherwin has seen evidence of the willingness he’s looking for. He decided on the larger version, the GoSun Grill, after polling existing customers and asking them how they liked to use the cookers they already had. On camping trips, for instance? Picnics? Seventy percent said they just used their GoSun Sports in the backyard, like a grill. They’re not living off the grid or preparing for the apocalypse, in other words, they’re just home cooks happy to have a cool new toy. (On Kickstarter, Sherwin has so far raised over $500,000, from 1,300 backers, toward the development of the new grill.) GoSun maintains a 2,300-person “community kitchen” on Facebook, where these backyard barbecuers post photos and talk about what they’ve been up to. Recent endeavors have included meatloaf, baked figs, scones for Valentine’s Day, “marinated quail and vegetables cooked on a bed of rice,” walnut-blueberry muffins, almond-stuffed dates wrapped in bacon, and a dispatch from somebody using the GoSun to get hot meals to homeless people in Yucaipa, California. Plus the guy who reported, “Ok so Tyson nuggets and ore Ida may not be the best thing to cook in the [GoSun] sport but it works.”

The day I visited, Sherwin used a prototype of the GoSun Grill to make a solar-cooked coffeecake, prepared from a mix from Trader Joe’s. I used to be a baker, and think of baking as a more finicky, more exacting form of cooking, in which certain cut corners or imaginative flights are punished as often as they’re rewarded. (Use less butter in that cookie recipe at your own risk.) Still, Sherwin casually reduced, by a quarter or a third, the amount of liquid called for in the recipe (because little would evaporate in the moisture-rich environment of the GoSun) and baked the cake (without a timer!) for an hour and a half, rather than the 45 minutes recommended on the box. There was no control version to compare it with, of course, but I couldn’t find a problem with Sherwin’s coffeecake. Didn’t even preheat the oven, either.

Sam Worley often writes about sweet things for Epicurious.