In an increasingly mobile society, we’ve found new and innovative ways to go wireless in almost every capacity. Cell phones replaced home phones long ago, and wireless internet, or wi-fi, is replacing Ethernet jacks at airports and hotels around the world as we speak. The advancement continues onward, as companies and governments all over the world begin the push for commercially viable applications of the ultimate wireless technology – wireless power transfer. However, the road to widespread use of wireless power beaming will be paved with many obstacles, and it will take the combined efforts of the military and private sector to bring this dream to fruition.
In some ways, this sort of wireless power technology has been “breaking into the market” for some time now. Inductive charging stations have been sold as an elegant replacement for the clutter of wires that recharge your many electronic devices. These nifty stations usually come in the form of a pad or some other flat surface, that inductively transmits power to receivers connected to your gadgets. Using similar technology, Sony and Haier have recently unveiled LCD television models that are “completely wireless.” While this does, technically, qualify as “wireless power,” the power transfer doesn’t take place over appreciable distances, which limits the number of applications for inductive power transfer. Though we have found new and interesting ways to power our electronics, freeing us from the power cables that once leashed us to outlets, the true importance of the concept of wireless power comes not in its low grade commercial applications, but on a much larger scale – a global scale.
Microwave power beaming has emerged in the past 50 years as a viable method for power transmission [1]. Recent experiments have proven the feasibility of long range power transmission at relatively high efficiencies. The National Aeronautics and Space Administration’s (NASA) experiment at Goldstone in 1975 sent 34,000 watts of power across a distance of 1.5 km at an efficiency of 82% [2]. A similar project was conducted in 2008 in which power was sent over 92 miles, albeit at a lower efficiency level. Both of these experiments used relatively low microwave frequencies, which require larger receivers and have lower transmission efficiency than higher frequencies. Researchers at Georgia Tech are currently exploring this technology for military and commercial applications under the guidance of Professor Narayanan Komerath. The team believes greater efficiency and transmission distances can be achieved with a higher frequency of around 220 GHz, especially if an appropriate waveguide can be designed for this application, which should cut down on propagation losses. To put that number in perspective, the millimeter wave detection system that is being used for screening in airports now operates in approximately the 24-30 GHz range.
There are certainly some significant challenges to conquer in the implementation of this technology, but the potential applications make investment in its development worthwhile. The United States Army spends millions of dollars just to transport the billions of dollars worth of fuel required to power forward bases in combat zones. Even worse, combatants in modern wars target fuel sources, rightfully seeing them as a vital component to a successful campaign. How can we prevent these losses? We can cut the wires and turn off the generators. The flexibility of wireless power transmission will allow the Army to reflect energy-bearing microwaves off of Unmanned Aerial Vehicles (UAVs) and naval ships and send it to these forward bases.
The Air Force and the Navy can find an even more diverse set of applications for this technology. A company called LaserMotive has already designed a system to keep UAVs in flight for days at a time by “refueling” them with surface to air power beaming [3]. If we can do this for UAVs, what is to stop us from one day powering helicopters, fighter jets, or even commercial airliners in this manner?
It’s important to look at the military applications first, as the infrastructure for this technology will have to rely on the military sector for construction due to the large amount of venture capital required. Many scientists see this as a necessary first step towards applying these designs to the commercial sector, in the form of a Space Power Grid (SPG). Space solar power has been a dream of NASA and other groups of scientists for quite a few years now, and many of their designs have real merit. The constraints lie in the astronomically high cost of lifting satellites into orbit, which is where the military comes in. The strategy laid out by Professor Komerath calls for a three stage deployment over 30 years.
The first stage relies on the military to develop the equipment and infrastructure necessary for power beaming. We can fully expect them to use this power beaming technology for the purposes discussed earlier, and for countless other projects that we cannot foresee at this time. The second stage will be based around the development of stratospheric platforms that can route power from regional power plants to homes and businesses around the world. The third and final stage will be the rise of full space solar power. Utilizing satellite to satellite beaming, the space power grid can ensure 24 hour access to clean solar power anywhere in the world, even at night. It might be an exaggeration to say that this will completely end reliance on fossil fuels, but it certainly will help.
Many of these ideas may seem hundreds of years away from implementation, but in reality, we can expect the beginnings of such a system to come about in the next fifteen year [4, 5]. The National Space Society (NSS) and former Indian Prime Minister Dr. A.P.J. Kalam will be leading a new initiative in Space Solar Power appropriately titled the Kalam-NSS Indian-American Energy Initiative. Former Prime Minister Kalam believes a working system could be in place within fifteen years.
The development of wireless power transfer has almost endless applications, from low grade commercial charging stations to a cheaper, cleaner power source for the whole world. While the initial investment will be extremely high for the pioneers in this field, the dividends it will return within a decade or two of implementation will be invaluable, both financially and environmentally [6]. If the system envisioned by Prime Minister Kalam and the NSS comes to fruition, the world will owe a great debt to India and the United States for taking this first step towards independence from fossil fuels and power lines.
References:
1. Rouge, Joseph. “Space‐Based Solar Power As an Opportunity for Strategic Security.” National Space Society. National Security Space Office, n.d. Web. 10 Nov 2010. <http://www.nss.org/settlement/ssp/library/final-sbsp-interim-assessment-release-01.pdf>.
2. NASA DVD on Space Solar Power: Exploring New Frontiers for Tomorrow. National Aeronautics and Space Administration: 2002, Web. 10 Nov 2010. <http://www.nss.org/settlement/ssp/NASADVD/part04.htm>.
3. Nugent, T.J., and J.T. Kare. “Laser Power for UAVs: A White Paper.” LaserMotive, LLC, n.d. Web. 10 Nov 2010. <http://lasermotive.com/wp-content/uploads/2010/04/Wireless-Power-for-UAVs-March2010.pdf>.
4. Barnhard, Gary. “National Space Society Announces the Kalam-NSS Energy Initiative.” October 30, 2010.<http://blog.nss.org/?p=2214> (accessed 12/1/2010).
5. Mankins, John. “A Fresh Look at Space Solar Power: New Architectures, Concepts and Technologies.”National Space Society. National Aeronautics and Space Administration, n.d. Web. 10 Nov 2010. <http://www.nss.org/settlement/ssp/library/1997-Mankins-FreshLookAtSpaceSolarPower.pdf>.
6. Brown, Trevor. “SSP: A Spherical Architecture.” Space Review n. pag. Web. 10 Nov 2010. <http://www.thespacereview.com/article/1383/1>.