Big Idea 1: Make Airplanes Rechargeable —————————————

Tesla. Prius. Volt. The auto industry is stocked with radical new designs that reduce the environmental impact of driving. The airplane industry has been incrementally improving fuel efficiency for decades, but it's maxing out the potential of current designs and will soon need to come up with a similarly transformative rethink. And it has to move fast. Air travel is set to explode—more than double by 2031—as developing nations grow more prosperous. That growth could eat away at any other improvements we may make from cleaning up cars or energy grids.

There are a number of ways to tackle the problem. NASA is rethinking airplane design by sponsoring eye-popping concepts like the MIT D Series—in which a double-cylinder body allows for rear-mounted engines and an overall fuel reduction of about 50 percent. (They're much quieter too.) Smarter navigation systems could let airlines fly shorter, more direct flight paths. And small, short-range planes could eventually become electric: The Slovenian firm Pipistrel has developed an electric four-seater, with double the mileage of a similar plane. "All these technologies are converging to produce capabilities that were not imaginable 10 years ago," says David Hinton, NASA's deputy director of aeronautics research. The sky's the limit. —Clive Thompson

Big Idea 2: Fuel the Planet with Micromachines ———————————————-

Harry Gray knows his electrons. In 1982 the Caltech chemist discovered that electrons "tunnel"—skip across long chains of molecules—through proteins. This trick turns out to be the animating breath of life; it's how living things convert energy into something they can use, from plants locking the energy of sunlight into their cells to pretty much every life-form burning fuels such as glucose to make power. It's all made possible by hybrid molecules called metalloproteins, which combine the shape-shifting flexibility of proteins with metals' ability to catalyze chemical reactions.

When Gray figured it out, he was already interested in solar power. If you were trying to develop a near-infinitely renewable power generator, he realized, you might try to hijack a metalloprotein-driven system like photosynthesis. But it wouldn't work. Biological machinery is too fragile and inefficient—and has to be resynthesized every few minutes to work.

If you want a molecular machine that'll make power efficiently and reliably, Gray says, you have to build it yourself. He and his colleagues envision microscale batteries with metal oxides at one end and silicon at the other, built like metalloprotein arrays in plant cell membranes. The metal oxides would absorb blue wavelengths of sunlight and use the energy to split seawater into oxygen and protons, and the silicon would absorb red light and combine the protons with electrons. That's slick, because a proton combined with an electron is actually hydrogen, which can be used as fuel. Shorter version: free hydrogen from sunlight. "The whole emphasis of our work is coming up with molecules or materials that are very robust," he says, "and will last a long time in solar fuel plants."

It might even work. Artificial water splitters are already 10 times more efficient than natural photosynthesis, though scale-up is still decades away, as researchers seek new catalysts to drive the chemistry. (The exotic metals they use today are pricey and toxic.) Still, Gray is optimistic. "The natural system had to build something that could actually live," he says. "All we have to do is make fuel." Oh, and save the planet. —Thomas Hayden

Big Idea 3: Spray Wi-Fi Hot Spots on Everything ———————————————–

The entire mobile economy is based on a tenuous assumption—that we'll be able to access the mobile web, whenever and wherever we want it, at ever-increasing speeds. The reality is not so rosy: We've already seen mobile carriers like AT&T and Verizon stop offering their unlimited data plans—and the struggle for bandwidth is going to be even more grueling as the number of tablets and smartphones continues to explode.

Limited access is more than just an annoyance, it's a mortal threat to innovation. By 2020, wireless technology is expected to have a global impact of $4.5 trillion. But growth depends on our ability to scale up. We need access that matches the number of devices demanding it.

Readily available Wi-Fi could help fix that problem. Internet and phone companies are already starting to deploy small cells—essentially tiny mobile phone towers that serve Wi-Fi along with 4G—in densely populated areas. But those companies have little incentive to build out the massive infrastructure required to connect the rest of the world.

One company has come up with a uniquely audacious solution—a Wi-Fi antenna in a spray can. Chamtech Enterprises has developed a liquid filled with millions of nano-capacitors, which when sprayed on a surface can receive radio signals better than a standard metal rod. With a router, Chamtech's antennas can communicate with a fiber network, receive signals from targeted satellites, and set up a daisy chain with nearby nodes, potentially creating a mesh network of low-cost, broadband Wi-Fi hot spots. Because the antennas can be painted onto any surface, there would be none of the NIMBY-ism that greets every new cell phone tower. If that's not fantastic enough, try this: No more cursing AT&T. —Rachel Swaby

Big Idea 4: Turn Deserts in Power Plants —————————————-

Don't think of arid expanses like the Sahara as desolate wastelands. Think of them as near-infinite sources of clean power. In six daylight hours, Earth's deserts soak up more energy than humanity uses in a year. Now an unlikely consortium of politicians, scientists, and economists from around the Mediterranean has a plan to harness it. "Desertec" would involve hundreds of square miles of wind and solar plants in the world's deserts, hooked into electrical grids to funnel reliable, renewable, and affordable power to more sun-challenged regions. Planners are hoping to get solar power flowing from North Africa to Europe first. An estimated 1,300 square miles of North African desert could handle 20 percent of Europe's energy needs by 2050. "All of what's necessary to realize the Desertec concept is already there," the foundation's codirector, Thiemo Gropp, says. As with most massive infrastructure projects, the biggest challenges are political. North African leaders see Desertec as a job creator, but the Arab Spring left investors uncertain about the region's long-term stability. Europe's economic crisis has drained public works funding, and the continent is a tangle of incompatible power grids and regulations. Still, the Desertec concept could travel. Ninety percent of the world's population lives within 1,800 miles of a desert. China's cities could be powered by the Gobi; South America could run lines from the Atacama. Where there's light, there's hope.

—Andrew Curry

Big Idea 5: Put Digital Displays in Your Eyes ———————————————

Smartphones have given us an always-on connection to the world's information. But actually accessing that information requires us to stare down at our gadgets, leaving us prone to fender benders and ticked-off dining companions. What if we could tap into all that information seamlessly, without risking our lives or friendships?

Google's cofounders have talked about a direct line into our brains since 2002. So far the closest they've come is the Google Glass prototype, eyewear that projects information onto a heads-up display, visible only to the wearer. But Babak Parviz, the founder of Project Glass, who is also an associate professor at the University of Washington, hopes to take things one step further. He suggests a long-range plan to do away with the bulky glasses and build a microsystem on a contact lens. Using radios no wider than a few human hairs, he thinks these lenses can augment reality and incidentally eliminate the need for displays on phones, PCs, and widescreen TVs. "The only thing those displays do is generate a pattern on your retina," Parviz says. "So if you have a contact lens that does that, you don't need any of those displays anymore." A bonus: The lenses could act as a persistent health monitor, using tiny biosensors to analyze your eye's cells. —S.L.

Big Idea 6: Declare War on Incoming Asteroids ———————————————

The movie Armageddon got two things right: First, we are woefully unprepared for an incoming asteroid. And second? The right tool for the right job. "Bruce Willis made a very significant contribution to planetary defense," says Bong Wie, director of the Asteroid Deflection Research Center at Iowa State University. See, Armageddon helped popularize the theory of subsurface explosions. And Wie has a missile—the Hyper-Velocity Asteroid Intercept Vehicle—that makes one. Up front: a "kinetic energy interceptor." In back: a nuke. The kinetic part drives into the rock, and the bomb blows it all to pieces. Hey, it sounded good to NASA; the agency gave Wie a $100,000 grant. The design addresses one of the biggest shortcomings of nukes in space. Slamming a bomb into the surface of an asteroid would cause the fissile material to melt down before it could detonate, and a stand-off blast wouldn't destroy the target. The HAIV puts the bomb inside the rock, where it creates ground shocks, magnifying the force of the blast twentyfold. Wie plans to test the system, sans nuke, around 2020, but he says he could get one airborne in less than a year if a collision looked imminent. "A lot of people in our community think whenever we need it we can just assemble the system I am talking about," Wie says. It'd cost $500 million, but that's a few grains of stardust compared with the end of civilization as we know it (and $50 million less than Armageddon's global box office take).

—Ben Paynter

Big Idea 7: Build Skyscrapers Out of Diamonds ———————————————

It's one of the hardest materials in the universe. It's utterly clear, virtually frictionless, chemically inert, and an excellent conductor of heat. And it's made of one of the most common elements: carbon. Diamond—just carbon crystal, really—is exceedingly useful in fields from microelectronics to water treatment. Unfortunately, large diamonds are also exceedingly rare. But imagine if the stuff were as ubiquitous as steel.

Stephen Bates might just make that happen. In addition to working for places like NASA and Princeton, the 64-year-old journeyman scientist spent a few years at General Motors, where he built a transparent piston engine using sapphire, yielding an unprecedented view of the flow of flames and gases. That sapphire motor got Bates thinking about diamond. "Anything you can do with sapphire would work better with diamond, if you could afford it," he says.

After immersing himself in research on the synthesis of crystals in thin films via a process called vapor deposition, Bates patented a method for doing the same thing for diamonds. The concept is simple: Pack diamond grit, an inexpensive industrial product, into a mold with vaporized C 60 fullerene—a soccer-ball-shaped cage of 60 carbon atoms. Then blast the whole thing with a laser beam. The fullerene breaks apart, and carbon condenses between the diamond particles, effectively fusing them into a relatively solid mass.

Even if the method proves technically and economically feasible, the resulting material would be porous, and no one really knows what properties porous diamond would have. Step one is for Bates to acquire a $100,000 pulsed laser. But if it works? Imagine diamond foundations beneath your home, diamond girders in skyscrapers, diamond bones in your legs, and diamond parts for airplanes and spaceships. Just don't plan on an all-diamond house—walls made of the world's best heat conductor would make for a pretty chilly place. —Ted Greenwald