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Monday, June 7, 2010

Laser Power Beaming – Creating the “Eternal UAV”

UAVs may remain airborne indefinitely when recharged by lasers.

DefPro News

Interview with Tom Nugent, President and Co-founder of LaserMotive

Since the demonstration of the first functional laser in May 1960, laser science and use of laser beams in everyday life has made gigantic leaps. Despite the progress of the past 50 years, much remains to be discovered in this field of technology. Defence applications traditionally use lasers to guide weapons or to mark, damage, or even destroy targets. Seattle-based LaserMotive has demonstrated a further ability of the red beam of light: transmitting power. Nicolas von Kospoth of defpro.com talked to Tom Nugent [1], President and Co-founder of LaserMotive, about the company’s recent advancements in using laser technology to power different mobile platforms, including unmanned aerial vehicles (UAV), and the LaserMotive’s plans to move on in this pioneering field of technology.


defpro.com: First, could you please give our readers a short overview of LaserMotive?

Tom Nugent: LaserMotive is a start-up company based outside Seattle, Washington. We are commercializing laser power beaming, which is the transmission of energy without wires. LaserMotive was founded in 2007 because component technologies had advanced to the point where the power, efficiency, and cost had all advanced to the point where we believed that laser power beaming was finally practical and economical for niche applications. Our first project was to pursue the NASA-sponsored Power Beaming competition, in order to demonstrate the technology and raise start-up capital from the prize. We won that competition in November 2009, and are now pursuing commercial opportunities, with the unmanned aerial systems (UAS) market being the most promising one to start.

defpro.com: The thought of laser transmitting power, at first, is a little abstract. Could you please explain the technical principle as well as the possibilities and challenges?

Nugent: In a manner very similar to the way that sunlight is used to generate electricity from solar cells, we use lasers to act as a very bright light on specialized solar cells. The laser beam can be directed in a very controlled manner to a receiver, and the power densities (along with low divergence) available in lasers enables us to deploy these “invisible extension cords” through narrow corridors in the air (in many cases, the beam is less than 1 meter in diameter).

One challenge is that inclement weather, such as fog or heavy rain, can block transmission. We operate in the near-optical region, so we are roughly limited by how far you could see with binoculars or a telescope. Interruptions of power would be managed with on-board energy storage. Another challenge involves eye safety. The optical power densities for power beaming are not immediately harmful to skin or other materials, but the most efficient wavelengths for power beaming lie inside the range of wavelengths which your eye can focus, thereby presenting a hazard to the retina. We deal with this issue with a combination of layered safety systems, including beam shut-off if anything comes close to interrupting the beam.

The possibilities for power beaming extend well beyond UAVs, and are what excite us so much about finally being able to bring this technology to market. Our white paper [2] describes various scenarios for UAV use, both short and long range.

We also see many possibilities in point-to-point power beaming, whether it is for remote sensors around a military encampment or base, or for remote communication relays (e.g., on mountaintops). Disaster relief is another application that could benefit greatly from power beaming. Imagine being able to immediately power cell towers or even an emergency field hospital in a city that has been devastated by an earthquake or hurricane.

Looking further down the road, we are excited by the idea of launching rockets via laser. LaserMotive co-founder Dr. Jordin Kare’s Laser Launch concept propels a rocket by means of a rocket-based heat exchanger heat up inert gas, leaving the more expensive power system on the ground.

defpro.com: What is the current development status of this technology and what have been the recent achievements in your efforts to further develop laser power beaming?

Nugent: We have developed laser power beaming for ground-based applications to Technology Readiness Level (TRL) 6 [System/subsystem model or prototype demonstration in a relevant environment – Ed.] as part of our winning entry in the NASA-sponsored Power Beaming competition. We are further developing it and expect to bring it to TRL 7 [System prototype demonstration in an operational environment – Ed.] in the near future. To date, our system has demonstrated power beaming up to 1 kilometre away, with the receiver creating up to 1 kilowatt of power. Power levels are easy to scale up, and distances can also be increased with different optics.

The last component to be finished and integrated (as part of our TRL 7 effort) is the safety system to make it suitable for use by non-experts. As mentioned in our UAV power beaming white paper, we are also creating an internally-funded demonstration of extended UAV operations with lasers.

defpro.com: LaserMotive has recently published a white paper on supporting UAVs. Which types of UAVs or other aircraft can use this technology and are there technical limits (e.g. due to weight/capacity of receiver and battery)?

Nugent: We see the first application of power beaming as enhancing the endurance of small UAVs that are already electrically powered, replacing part or all of the batteries on board. However, there are no inherent limits to the power we can deliver, and we can easily match the power-to-weight ratios of small combustion engines with our receivers plus high-performance electric motors. The advantages of electric motors in terms of reliability, efficiency, and noise are well known, so we would hope to work with manufacturers of larger UAVs to develop laser-electric versions in the future.

One square meter of receiver area can provide several kilowatts of electric power, and receivers can be integrated into wings or body surfaces or (subject to aerodynamic and mechanical limits) carried as external panels. For some applications, all power could be provided by the laser, with little or no on-board power storage. For others, where the vehicle needs to fly out of range of the laser or to stay on station for some time despite interruptions in the laser beam, batteries or fuel cells can supply power when needed, and then be recharged in flight when laser power is available. But as long as the vehicle has laser power available for more than a few minutes per flight, we can reduce the overall vehicle weight by replacing batteries with our receivers.

defpro.com: At which range can laser power beaming support UAVs and which weather conditions and flight patterns are required to transfer power? Is it possible to simultaneously transfer power to multiple UAVs?

Nugent: Our current power beaming system has been demonstrated to work over 1 km, and we expect to be able to reach 10 km or more using the same high-efficiency technologies. We also have conceptual designs for systems which would work over almost any range - even from the Earth to the Moon! - but right now those would be significantly more costly per watt delivered. Clouds, fog, and heavy precipitation will block our lasers, but those are generally unfavorable conditions for flying small UAV’s in any case. Flight patterns can be very flexible; as long as a vehicle is within line of sight of a laser, it can receive power. However, we can trade off some of that flexibility for system cost and complexity; it’s easier to build a beam director that only has to track a plane circling overhead than one that has to aim anywhere in the sky.

We’re currently working on the most straightforward power links: one laser system and beam director powering one UAV at a time. That can include charging several UAVs, but sequentially, with the charged UAVs flying on batteries until their next turn in the beam. But nothing prevents several such links operating at the same time; they would not interfere with each other.

defpro.com: Many UAV manufacturers come from abroad, including a score of Israeli and Western European companies. Are you looking at these markets and do you see opportunities for co-operation in the short to mid term?

Nugent: We’re certainly interested in the possibility of working with manufacturers and users of UAVs worldwide. For a small company introducing new and potentially revolutionary technology, the complexities of export regulations and the logistical requirements of global collaborations are a bit daunting, so our immediate focus is on domestic opportunities. But we would certainly encourage anyone interested in our power beaming systems to contact us, and we’ll see what we can do.

defpro.com: In your white paper you describe different scenarios which give the impression that, indeed, there are few limits and a score of possibilities to discover and develop. This includes relay mirrors on airborne platforms or flying power beaming systems that could be consider as “laser power tankers.” How far from reality are such solutions so far?

Nugent: Relay systems are currently only in the conceptual stage for us. There have been technical demonstrations of high-altitude (low power) laser relays, but developing that capability for power transmission still needs to be done. Similarly, there have been demonstrations of high power lasers beamed from aircraft for directed energy purposes (e.g., the Airborne Laser), but for power transfer the requirements are different and would need to be developed.

The time required until such systems could be deployed depends primarily on interest. We are taking a staged approach to technology development. We are starting commercialization at the lower power levels (e.g., hundreds of watts up to a few kilowatts) and shorter distances (e.g., up to 1 kilometer) and will expand to higher power levels and longer ranges once we’ve demonstrated commercial success at the smaller-scale systems. By growing organically in this manner, we not only gain experience in many technical and operational issues needed for the bigger systems, but we also can work with regulators to understand how power beaming is different from other uses of lasers.

defpro.com: Which other possibilities to use this technology in military applications beyond aerial platforms can you imagine? Are there projects to apply laser power beaming to defence areas beyond the field of UAVs?

Nugent: There are many applications of ground-based point-to-point power beaming for both military and civilian use. Remote sensors (especially for perimeter use at smaller bases) and remote communications relays (e.g., microwave relay towers on mountain tops) are two areas we think could benefit greatly from power beaming. In both cases, electrical power is delivered either by swapping out batteries or by running power lines over long distances, oftentimes through areas where it is expensive and/or undesirable to run lines.

We also think there are applications in disaster relief. Imagine being able to rapidly re-establish cell phone towers or even power a field hospital in a city where the power grid is down and roads are too damaged to easily allow moving generators into the city. We’ve spoken with personnel in the US military about their disaster relief efforts in Haiti, and there is definite interest in this application.

defpro.com: Sponsors such as Boeing may give you a head-start on your competition. How do you assess the current (international) competition in this field of technology?

Nugent: As far as I know, we are the first company with proven hardware to be selling laser power beaming systems, certainly at these power levels and distances. We are deeply appreciative of The Boeing Company’s sponsorship, and we look forward to partnering with them in future power beaming applications if possible. Down the road, once we prove that money can be made in this new market of power beaming, we expect direct competitors will arise but they will be facing the learning curve that we’ve already climbed. In the meantime, we’re competing against existing products which are substitutes, i.e., batteries, fuel cells, etc.

defpro.com: What are the next steps for laser power beaming at LaserMotive, including industrial co-operation? Which are the next key milestones of your projects?

Nugent: We are going to be demonstrating an extended endurance helicopter using internal funds in the next few months. We’re looking broadly at UAV companies right now to find the right partner for creating the first “eternal UAV” - an electric UAV powered by laser. We’ve also been contacted by many companies interested in other specific uses that we can’t divulge yet.

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