A year ago ComputerWorld predicted that wireless charging would soon come to personal computers., It hasn't happened yet, but its likely that Macs will run via wireless power sooner rather than later.
ComputerWorld’s vision: “Place a laptop on a table, and it'll automatically start charging. No wires needed, no need to carry a power brick. That's how Intel views wireless charging for laptops, which could become a reality next year. Intel wants to make wireless chargers as easy to find as a Wi-Fi signal, and wants to bring the technology to cafes, restaurants, airports and other public places so laptops can be recharged without power adapters. The first laptops with wireless charging could come out next year, and Intel has shown a few prototypes laptop being recharged on a table.”
Intel is backing the Rezence magnetic resonance wireless charging technology, promoted by the Alliance for Wireless Power, or A4WP. The power flow will initially be limited, enough to wirelessly recharge ultraportables and hybrids. Plans call for increased power output to recharge mainstream laptops. But getting the technology to public places and entertainment spots could take some years.
So far Apple hasn’t committed to Rezone. The company is likely to see which wireless charging spec proves to be the most robust. In addition to Rezence, there is also Qi, which is supported by the Wireless Charging Consortium (WPC) and Powermat, which is backed by the Power Matters Alliance (PMA).
However, Apple has looked into the technology, as evidenced by its patent (number 8,598,747) for "wireless power utilization in a local computing environment.”
Per the patent, the wireless powered local computing environment includes at least a near field magnetic resonance (NFMR) power supply arranged to wirelessly provide power to any of a number of suitably configured devices. In the described embodiments, the devices arranged to receive power wirelessly from the NFMR power supply must be located in a region known as the near field that extends no further than a distance D of a few times a characteristic size of the NFMR power supply transmission device. Typically, the distance D can be on the order of 1 meter or so.
Here's Apple's background on the invention: "Energy or power may be transferred wirelessly using a variety of known radiative, or far-field, and non-radiative, or near-field, techniques. For example, radiative wireless information transfer using low-directionality antennas, such as those used in radio and cellular communications systems and home computer networks, may be considered wireless energy transfer.
"However, this type of radiative transfer is very inefficient because only a tiny portion of the supplied or radiated power, namely, that portion in the direction of, and overlapping with, the receiver is picked up. The vast majority of the power is radiated away in all the other directions and lost in free space. Such inefficient power transfer may be acceptable for data transmission, but is not practical for transferring useful amounts of electrical energy for the purpose of doing work, such as for charging electrical devices.
"One way to improve the transfer efficiency of some radiative energy transfer schemes is to use directional antennas to confine and preferentially direct the radiated energy towards a receiver. However, these directed radiation schemes may require an uninterruptible line-of-sight and potentially complicated tracking and steering mechanisms in the case of mobile transmitters and/or receivers. In addition, such schemes may pose hazards to objects or people that cross or intersect the beam when modest to high amounts of power are being transmitted.
"A known non-radiative, or near-field, wireless energy transfer scheme, often referred to as either induction or traditional induction, does not (intentionally) radiate power, but uses an oscillating current passing through a primary coil, to generate an oscillating magnetic near-field that induces currents in a near-by receiving or secondary coil. Traditional induction schemes have demonstrated the transmission of modest to large amounts of power, however only over very short distances, and with very small offset tolerances between the primary power supply unit and the secondary receiver unit.
"Electric transformers and proximity chargers are examples of devices that utilize this known short range, near-field energy transfer scheme. What is desired are methods, systems, and apparatus for efficient and user friendly interaction between peripheral devices in a wirelessly powered local computing environment."