Whi te Pa per # 1 2 0 ( Dr af t: J ul y 2 0 0 9)
Author: Paul Goodrum, P.E., PhD. and Steve DeLoach, P.E.
B r eakt h ro u gh St r at eg y C o mmit t ee
Inductive Power Transfer
(Wireless Transmission)
1. Need and Potential
Facility design and space layout are constrained by a host of requirements, including power transmission from the
source to the receiving device or load. Active construction sites are overrun with temporary, cumbersome, costly
and dangerous, power cables. Construction has long sought to cut the cord of electrical power. A nagging issue on
many construction jobsites as reported by Research Team 215 (Work Force View of Construction Productivity) is
the ability to connect enough power cords to provide the energy at the work face where it is needed to power
lighting, power tools, and other energy consuming components. Protecting the power cords from damage, primarily
from travelling construction equipment, can be another challenge in and of itself. Cordless tools have addressed this
concern in part and have shown to increase productivity, but another challenge of maintaining adequate battery
charge on a daily basis occurs. The technology behind wireless transmission of power is not new; the physics to
transmit power without wires was demonstrated by Nikola Tesla in the late 1800’s. More recently scientists at MIT,
Intel and the University of Auckland revitalized these experiments. Some have begun development of commercial
devices for application in the manufacturing industry.
2. Background
When Debbie Boone sang “You Light Up My Life” in the 1970s, the song
could have easily been dedicated to Nikola Tesla whose work at the turn of the
20th century resulted in 221 worldwide patents and 113 US patents primarily
focusing on technology surrounding AC power alternators, wireless
communication, and fluorescent lighting. One of Tesla’s more notable
endeavors was in the area of wireless transmission of power. Based on his
original concept of the Tesla Coil, Tesla had even begun development of
Wardenclyffe Tower in 1900 (Figure 1), which was originally underwritten by
J. P. Morgan for the purpose of wireless radio transmission, but Tesla began
modifying the tower for the purpose of wireless power transmission. J. P.
Morgan cancelled funding of the program when he learned of the change in
scope. Tesla eventually denied penniless and alone in the New Yorker Hotel in
New York City in 1943. Tesla’s work was predated by Faraday, who
discovered the capability of magnetic fields to transmit power over short
distances.
Figure 1: Wardenclyffe Tower, Long Island, New York.
3. State of the art
While Tesla’s original concept of wireless power transmission was never commercialized, several versions of the
concept exist today. The concept of beaming power through air to create a measurable reaction is used in passive
RFID tags. With the development in December 2008, the Wireless Power Consortium has set its sights of wireless
power adaptors for the purpose of wirelessly charging cell phones, personal data assistants, and other battery
powered devices. At the 2009 Consumer Electronics Show in Las Vegas, Bosch demonstrated the potential for a
modified tool box with the capability of wireless charging power tools stored inside.
While the systems being pursued through the Wireless Power Consortium and the Consumer Electronics Show are
primarily target short distance (inches) applications, work is on-going to investigate the possibility of transmitting
power over much larger distances. Pittsburgh based Powercast has developed wireless transmission systems that
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cover distances less than 5 feet that uses radio waves to transmit the power. The system uses a similar concept to
crystal radios, which are passive devices that focus on receiving and preserve as much electrical power as possible
from the antenna and convert it to sound power whereas ordinary radios amplify the weak electrical energy "signal"
from the radio wave. Another approach by Silicon Valley based Powerbeam focuses on the use of lasers to beam
power from point to point.
4. Gaps
There are gaps and other concerns to wireless transmission systems. First in regards to the long-distance approach
systems, there are significant concerns about potential negative effects to both environmental and human health.
These devices often rely on high intensity energy transmissions, which might be hazardous but certainly difficult to
obtain regulatory approval. Second, there are concerns that wireless power transmission systems are not nearly as
efficient compared to their corded counterparts. If the wireless transmission system was designed to provide power
ubiquitously, it is likely that if most of the transmitted power is not used that it will just dissipate and in essence
create a “vampire load” on the system. Supposedly, laser systems under development are transmitted only when
demanded but would require an unobstructed line of sight.
4. Recommended Path Forward
While the prospect of wirelessly transmitting power over long distances, e.g. miles, is fascinating, this will likely not
happen in the near future due to environmental health and safety concerns. The most immediate impact to
construction appears to be Bosch’s approach of providing wireless power to battery operated hand tools. Most of the
literature suggest that wireless power transmission is less efficient and thereby more costly than corded power.
Bosch has at least investigated the possibility of a construction specific application, but could the inefficiency be a
significant barrier to its successful commercialization? The answer likely relies on the scale of electricity used by
construction tools, and research could estimate this. It is likely that a wireless power tool box will require a specific
economy of tools for it to be feasible, but the number and size of the tools appears to be unknown. If the
inefficiency appears acceptable, an independent demonstration of the system on an actual jobsite could significant
lessons learned on the capabilities and limits of such a proposed system. Such a research effort could be funded
through a CII research team or a venture through a FIATECH investigation.
5. References
Auckland Uniservices (2008) Inductive power transfer (IPT)
http://www.uniservices.co.nz/pageloader.aspx?page=1484d8d0d82
Economist. (2009). “Adaptor die” March 5 th, 2009 print edition.
Greene, K. (2006). “Charging Batteries without Wires.” Technology Review. Massachusetts Institute of
Technology.
Wikipedia (2009) Wireless energy Transfer
http://en.wikipedia.org/wiki/Wireless_energy_transfer
Science Daily (2008) MIT Demonstrates Wireless Power Transmission
http://www.sciencedaily.com/releases/2007/06/070607171130.htm
Yabroff, J. (2008). “The Cult of the Volt.” Newsweek Magazine. March 24, 2008 print edition.
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