In “The Next 100 Years” Dr. George Friedman gives us a barely familiar technological landscape. Friedman, a strategist at Geopolitical Futures, sees solar energy—harvested from photovoltaics in outer space—as the primary source of electrical energy used on the ground (i.e., on the surface of the Earth). Electrical energy is beamed via microwave transmission to ground-based receivers. The captured energy could be weaponized (used to shoot down enemy satellites or space stations), but Friedman’s most dramatic prediction, is the ability to (wirelessly) transmit megawatts of electrical energy from one location to another.
This is not science fiction, though Friedman’s other projections—like a space-based war with Japan, or economic competition with Mexico—may strike most readers as slightly bizarre. Having said that, Friedman insists the wireless harvesting of energy from panels in space will occur, likely before the end of this century.
We’ve actually had a little adjustment time to the vision offered by wireless energy transfer. Cell phone battery chargers—particularly inductive models—provide the ability to refresh our rechargeable batteries at a coffee shop or airport lounge, without fiddling with wires or connectors. The technology for charging your phone is essentially the same as technology for charging your electric toothbrush: it depends on tight magnetic coupling between power transmission and receiver coils.
While cell phone charging systems are becoming increasingly popular, technologists are already imagining the next stage in the commercialization process: Market-wise, accepting the wireless charging vision would benefit from new product introductions by consumer electronics companies. Technology-wise, we must increase the physical distance over which an electrical charge is transmittable and receivable, along with the electrical power that can be transferred this way.
Current inductive or resonant chargers offer about five watts of power. More power (10 watts)—as for a QuickCharge system—could minimize the users’ time, waiting (say) for their cell phone battery to top off at a coffee bar. The next generation of this technology (15 watts) would support charging systems for e-books and tablets. A 25-watt transfer would enable wireless charging for tablets; 40 to 60 watts would support laptops. Both types of wireless energy transfer—inductive (in which a transmitter coil induces current flow in the receiver), and resonant (in which the oscillation through a receiver coil mirrors the pulsed DC frequency of the transmitter)—rely on magnetic transfer through tightly wound coils, transferring energy like a high-frequency power pump.
Larger Charging Pads
Greater distance between transmitters and receivers remains high on the wish lists for wireless power technologists. Of the wireless power technologies endorsed by the Wireless Power Consortium (WPC) and the AirFuel Alliance, resonant technology allows for somewhat greater distances between power transmitters and receivers—and makes placement of a cell phone on a charging pad less critical. With cell phone and mobile devices, transmitting coils are embedded in a charging pad. However, the use of large pads to recharge laptop computers (or electric vehicle batteries) represents an ongoing challenge.
Beaming Energy Room to Room
As speculative as energy beaming seems, scientists and engineers are already working on the vision. Outside of resonant charging, there are numerous companies exploring (and promoting) utilizing of RF energy as the vehicle for transferring electrical power.
Technology reporters like the vision of charging cell phones and mobile devices untethered. They frequently compare the idea to Wi-Fi: We get our office internet access this way—why not our power? “Power-thirsty devices would get charged automatically, the moment you walk into a room with them,” claimed a reporter for USA Today.
A battery-powered device’s position on a resonant charging pad may not be critical, but the pad is typically stationary—the phone is fixed in place while the battery is being recharged. With RF carriers, the phone can be recharged anywhere within a large field—even while that phone is moving.
The technology is said to be implemented in “iterations” or phases, called far-, mid-, and near-field. The far-field energy can cross a 15-foot room. Mid-field (a transmitter, say, on your desk) charges everything on your desk or cubby. Near-field would be equivalent to inductive charging, one device at a time. The company says the first near-field products will be on the market at the end of 2017. The third iteration—supporting charging over a 15 to 18-foot span, the length of a family den—will not appear until early 2018.
