Electric power without lines by Brian Dumaine @FortuneMagazine November 1, 2013, 1:36 PM EST E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — Backed by the financier J.P. Morgan, Nikola Tesla, the inventor and rival to Thomas Edison, built in the early 1900s the Wardenclyffe Tower, a 187-foot-high structure on Long Island, which he said could transmit electricity wirelessly. The project failed, and Tesla ended up broke. (In an earlier experiment in Colorado, Tesla had wirelessly lit up 200 lamps over a distance of 25 miles, but pedestrians witnessed sparks jumping between their feet and the ground, and electricity flowed from faucets when turned on. Oops.) Fast-forward over a century, and wireless electricity is finally gaining some traction. More than one hundred companies including startups such as WiTricity and ProxybyPower and giants such as Toyota TM , Intel INTC , Samsung, and Foxconn are investing in the technology. The challenge: to take the wires out of the power equation by transmitting electricity through magnetic fields. When in the atmosphere, electricity exists as a magnetic field. The trick is to capture it safely to recharge devices. Today’s electric toothbrushes charge wirelessly — as power is transmitted through a magnetic field from the charger to the brush. You can already buy wireless recharging pads: Place your cellphone on a pad that’s plugged into the wall, and it will recharge. These pads, however, have their limitations — the cellphone has to be in the right position, and it can take a long time. A New Zealand company called PowerbyProxy has demonstrated a system where you can put multiple cellphones on a pad in any position, and it will charge the devices as fast as a traditional charger. Samsung last month invested $4 million in the company. MORE: Taking Toyota’s hydrogen car on the road The next step: charging without being so tied to a pad. That’s the technology a Watertown, Mass., company named WiTricity is developing. Based on work done at MIT, the technology — on which the company holds exclusive patents — uses magnetic resonance to move power through the air — which means electricity can be moved farther distances without a wire. The way it works: Two devices resonate at the same frequency so that the magnetic waves can travel very precisely from one point to another. Plug a resonator into a wall outlet, and a device installed on a cellphone or an electric car receives the power and starts recharging. WiTricity says its system can move an impressive 3,300 watts — enough to charge an electric car — with little efficiency loss. Says Eric Giler, the CEO of WiTricity: “We all love electricity and are willing to do almost anything to get it. It will be the last thing to go wireless, but it will go wireless.” Is the process safe? Because electricity moves through the air as magnetic waves that are similar to the earth’s magnetic waves, it poses no harm to humans, says Giler. The FCC has set limits for magnetic fields, and WiTricity claims its devices fall well below that threshold. The industry, however, will still face a tough time educating and persuading consumers that these devices are safe. MORE: All Energy Revolution coverage In recent weeks, Intel and Hon Hai/Foxconn, seeing wireless charging as a possible killer app for electronic devices such as laptops and cellphones, invested in WiTricity. Schlumberger, which is interested in cutting the number of wires in its oil rigs to save maintenance costs, was an early investor, as was Toyota, which is reported to have plans to test a wireless charging station for plug-in cars. The technology has applications outside the consumer sphere as well. WiTricity is working with the Pentagon to wirelessly charge those robots that disarm bombs. When soldiers try to plug in the robots for recharging, they sometimes get shot by snipers. Doing it wirelessly would reduce the danger. In the medical world, patients with heart pumps have to have electric wires running out of their bodies, which can cause infections. WiTricity is working with heart pump maker Thoratec to create a wireless solution. How long before this technology becomes a reality? All these applications are in the testing stage, but Giler says that within the next couple of years many of them will be hitting the market. Until then, where did I put that cellphone charger again?