A car that drives itself and emits nothing but water. A watch that remotely turns lights on or off. A home that produces power for neighbors during a blackout.

These three don?t belong to the future. They?ve already arrived. They're part of a new tech era in which scientists and entrepreneurs are rapidly trying bold ideas to save energy or provide cleaner alternatives.

1. Self-Driving Vehicles

Some of the world?s biggest companies are investing big bucks to build electric vehicles that partly or entirely drive themselves.  Proponents say these cars could reduce traffic accidents and save energy via more efficient routing and ride-sharing.

2. Fuel Cell Cars

Toyota, maker of the Prius—the best-selling hybrid car—is also moving ahead with a mass-production fuel cell sedan. The Mirai, which converts hydrogen into electricity and emits nothing but drops of water, made its debut in California this month and will be rolled out next year in several European countries.

The Mirai—a Japanese word that means ?future?—can go 310 miles on a single tank. That range is greater than any electric car on the market (even Teslas) or the current hydrogen-powered competitors—the Honda FCX Clarity and the Hyundai Tucson Fuel Cell.

3. Advanced Nuclear Reactors

Though controversial with environmentalists, nuclear power has caught the eye of tech titans, dazzled by its potential to provide abundant energy with little or no planet-warming emissions.

Some are pursuing the holy grail: fusion, the power source of the sun and other stars that scientists have sought for decades to harness for use in large reactors. Companies such as Lockheed Martin and General Atomics are funding small-scale projects they expect will be cheaper and simpler.

4. Wave/Tidal Power

This year marks the launch of the world?s first multi-machine, grid-connected wave energy project, by Carnegie Wave Energy off the coast of Australia. Its technology, under development for a decade, is unique because it operates underwater where it?s safe from large storms. Buoys, tethered to seabed pumps, move with the motion of the waves and drive turbines that produce power for up to 2,000 homes.

5. Efficient Solar

Solar is taking off as its prices have plummeted, an estimated 70 percent since 2009, according to a September report from Lawrence Berkeley National Laboratory. This plunge occurs as researchers find new ways to make solar not only smaller, see-through, or sticky so it can be used almost anywhere—whether roads, golf courses, or landfills—but also more efficient.

Read more at:

http://news.nationalgeographic.com/energy/2015/12/151228-eight-tech-breakthroughs-that-could-help-power-the-world/

PHOTOGRAPH BY TONY AVELAR, AP