Wireless energy transfer

New research is bringing energy transfer into the wireless world. Soon, a central hub could be charging your batteries, laptop, televisions, electric cars, right through the air.

Over the past few years, a number of companies have been racing to put wireless energy on the market. In 2007, researchers at MIT revealed a project that powered a light bulb remotely. The physicist and project leader Marin Soljacic (winner of a MacArthur “genius grant” Fellowship) went on to found the start-up WiTricity.

In the 2007 expeiment they powered a 60W light bulb across a room. At the Nikkei electronics conference in Tokyo in October 2009, they were able to power a 1,000-watt klieg light from across the room. WiTricity’s record so far is 3,000 watts – enough to fully charge an electric car, so long as it’s in the same room (or garage).

The basic underlying principle for transmitting power wirelessly goes back more than a century to the work of Nikola Tesla and other pioneers of electricity, but the MIT team invented a way of making the process far more efficient and practical.

The system works by creating a strong electromagnetic resonance between the sending and receiving coils – similar to the way a tuning fork can start vibrating when exposed to a sound of exactly the right frequency, or the way a radio antenna can be tuned to just the frequency of a single station out of the hundreds that are simultaneously broadcasting their signals. In this case, the magnetic resonance between the two coils is unaffected by objects in between the coils, and by the same token objects between the coils – including people – are not affected by the magnetic fields.

Several concerns, even initially from WiTricity CEO Eric Giller, have been raised about the potential health risks as magnetism from MRI machines can disable pacemakers. But, MRI magnetism is about 10,000 stronger than that in WiTricity and the Institute of Physics in London has found WiTricity’s magnetic field “has no detrimental effects on the human body.”

Already, companies focused on a special application of wireless electricity have broken into the retail market with force. Powermat, and soon WiPower, provide “wireless charging” stations for home electronics. Instead of plugging in your mobile phone or handheld video game, you just strap a receiver on it, and place it on a charging mat. This “drop and charge” innovation is set to make a big impact in retail sales (Powermat sold more than 750,000 products in just two months) and could be the first step to the wireless electricity revolution that changes the way we power our lives.

Gieler of WiTricity mentioned at the TED 2009 conference that the technology can conceivably still get a lot better. We could use a similar method of coupling to power objects from a meter away or farther. At that distance, we could power electric cars while they were still on the road, or create homes without plugs.

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Small, clean, green machines

MIT CityCarWhile mass transportation systems such as trains or busses are hailed as the solution for urban mobility, there is often the problem with the last mile. MIT Media Lab (with support from GM) has developed a small car, the CityCar, specifically to be used in an urban context and for car sharing.The 2-seater cars are fully electric and also stackable. They work a bit like shopping carts in when the behind car touches a parked one in front, the front car lifts its body enabling stacking. When you want to drive off again, you merely touch a button and the front car disengages and moves slightly forward. The idea is that anyone uses any car.

A further feature is that the cars are capable of 360° steering, making parking a dream.

Because the cars are part of a single, computerized network, their placement can be coordinated to reduce traffic congestion or make transportation options available at peak times and places. Rental charges could fluctuate to encourage alternate routes. Commuters could keep track of where and when cars and parking spaces are available in real time, using cellphones or other hand-held devices to track the cheapest or the most convenient car, spot, or route.

Ryan Chin, one of team working on this project, said: “When you think of this, you shouldn’t think of a car. You should think of it as a new personal and sustainable mobility system and service. This is a clean and green machine.”

MIT has submitted a proposal to a government in Asia that is interested in building a network of these cars in one of their cities. The CityCar was part of the plan submitted by MIT that also recently won the 2009 Buckminster Fuller Challenge.