Beaming Laser Power: An Interview with Tom Nugent of LaserMotive
Tom Nugent is a busy man. When I contact him to ask him about his new company, LaserMotive, he tells me that he’s in the middle of some optical modeling. “We use a software program to model the light as it goes through our system to plan the optics,” he said. “We need to get the lens and focal length chosen with positions and angles all set to see how compact we can make it without having light going the wrong way.”
Getting lasers correctly tuned is only one of the many things that Tom does at LaserMotive. Prior to co-founding the company with Dr. Jordin Kare, an expert on laser rocket propulsion and optics who worked on the “Star Wars” nuclear-missile defense system, Tom worked at Intellectual Ventures, an innovative company led by former Microsoft chief architect Nathan Myhrvold. One of his projects there was the so-called “photonic fence,” a laser mosquito-zapping system to help prevent the spread of malaria.
The idea of wireless laser power transmission has been around for many years. But cheaper and more energy-efficient diode lasers have made it possible to pursue the idea commercially only recently. Tom notes that the use of lasers for hair removal and rock concerts has contributed to reducing the cost of lasers. Here’s a video showing the sophistication and power of lasers for concerts and other events:
LaserMotive has plans for several laser power beaming applications. Ultimately, Tom would like to see the company use lasers to beam power to Earth from orbiting satellites. Winner of the NASA-sponsored 2009 Power Beaming Competition, the company is currently focused on baby steps — a recent press release describes a project to demonstrate the first endless power system for unmanned aerial vehicles (UAVs).
h+: Your recent press release mentions that you expect to demonstrate unmanned aerial vehicles (UAVs) that use power beaming before the end of the year. Isn’t that a fairly ambitious goal?
TOM NUGENT: We’re actually aiming to do a small-scale demo that’s going to be funded internally… a little helicopter… this year. Our long-term goal is to commercialize some of the very cool applications of laser power beaming — beaming power from space down to earth or even launching rockets with lasers. But that’s a long-term goal that’s going to require a lot of work before we can get there.
Historically, when people talked about beaming power from space, they talk about putting these giant systems in space. It’s impossible to get something like that funded even if it makes sense from an engineering perspective. You want to learn a lot from smaller systems beforehand. Our philosophy is to start with small steps and work towards beaming over relatively short distances at low power, turning that into a commercial product along the way. That way, we hope to generate revenue to feed the development of the technology.
The first application we want to commercialize is powering UAVs. Currently, some of these run on batteries and some run on fuel. The ones that run on batteries can easily be retrofitted to run off laser power. It’ll be beneficial to convert those to laser power because then you don’t have to waste the time, the manpower, or the hardware to have these things keep coming back to refuel or recharge their batteries.
h+: What distances do you anticipate?
TN: It can be anywhere from a few hundred meters all the way up to tens of kilometers. You do get issues with atmospheric interference at tens of kilometers and we would have to switch to a different laser system than what we’re using now. However, current longer-range systems are less efficient.
h+: How do you get the extended range? Does this involve some sort of hybrid technology?
TN: We’re looking at an option to have vehicles come within range of the lasers, within five to ten kilometers, get a charge, and then fly a mission. There may be some applications where going and coming to recharge in the air is adequate. We’ve got lots of interest from the military for applications of this technology for UAVs.
Another short-term application we’re considering for power beaming is point-to-point on the ground. There are military applications for, say, sensors where you have a special forces group out in the field and you set up a perimeter with sensors in a location where those sensors may be very far away from your encampment. And rather than sending a person out and either getting him detected or inside the line of fire, you beam power to the sensor. Another variation that is technically very similar is to beam power to a location that has been hit with some natural disaster. The Navy, for example, did a lot of disaster relief after the Haiti earthquake where it was difficult getting power into the middle of the city or to some of the outlying areas. You can imagine putting a laser on a boat or a truck to outside the affected region where it’s relatively impassible and then beaming power into the area where you could power emergency communications or field hospitals. So, we’re looking at all these applications in the near term.
h+: Can you tell me a little bit about your background and motivation for starting LaserMotive?
TN: I’ve had a very long interest in space development — going to space and helping humanity by utilizing resources that are in space. For a long time, I was frustrated because the big obstacle to doing all the interesting things that you can do in space is the high cost of getting to orbit. I spent a lot of time looking at different ways to reduce the cost of getting to orbit. I spent time working on the space elevator before deciding that wasn’t going to happen on Earth in my lifetime. During that time I met Jordin Kare, the co-founder of LaserMotive. He’s really the expert on laser power beaming. He’s been working on it for decades now and has very interesting ideas for launching rockets with lasers. I saw lasers as a way to potentially address multiple areas of interest in space: one is getting power down to Earth, and another is maybe getting power up into space.
h+: How soon do you think we’ll be able to beam power from satellites in space?
TN: That question has a very complicated answer. Traditionally, most people who talk about beaming power from space talk about doing it with microwaves. The atmosphere is more transparent at certain microwave wavelengths than it is for optical lasers. The problem with microwaves is that their wavelength is so much longer that it means your antenna for transmitting and receiving has to be huge — extremely large. And people have been sort of focused on using microwaves. There are one or two private companies that allege they are developing microwave power beaming from space. One company, Solaren, has a contract from the California utilities. The utilities are saying “if you can deliver power from space, we’ll buy it.” I believe that Solaren wants to have a demonstration up in 2015 or 2016. I don’t see how they can have something up and beaming any reasonable amount of power in that timeframe. The money required to build what they’re proposing is huge. And I don’t know whether they intend to start with small systems and scale up, or whether they’re expecting something larger in the 100+ megawatt range right away. For utility-level power beaming from space, I think 2015 is a little optimistic.
The nice thing about lasers, however, is that your antenna can be much smaller. This means you can do a demonstration project that produces useful levels of power from a smaller package, meaning much lower launch costs. Your overall budget for a demonstration is also much smaller. It may cost something on the order of $100 million whereas for a microwave system it’s going to be billions of dollars. There’s a big difference there. You can also imagine niche applications for lasers. The military is very interested in power beaming to small forward bases in remote areas so they don’t have to truck fuel across dangerous roads. So before you see utilities buying power from space, you’ll probably see relative small niche customers in the kilowatt range.
h+: How is your company going to get lasers into space?
TN: We’re going to have to partner with someone else. We’re a small company, and our core competency is power beaming — we’re not satellite or rocket builders. This will all depend on what level of interest we get. If no one wants to put up a demonstration, it may take us 10 to 20 years to build sort of our own “war chest” as we get all these other projects going until we can fund it ourselves. But, if there’s interest in funding a power beaming demonstration, then it can happen sooner.
h+: Getting the package into space will require something like the Evolved Expendable Launch Vehicle (EELV), right?
TN: Exactly. We’ll have to buy launch services from someone. The nice thing about the laser demo is that it can sit on a single launcher… even half of one. The systems aren’t so big that they require multiple launchers. The other thing we’d like to work on is the laser launch. We have the hardware to do some small demonstrations, basically generating rocket thrust from lasers. And I’ve heard rumors about a prize challenge for some sort of laser launch. That would be an interesting way to kickstart that development.
h+: Do you own any patents on the technology?
TN: The laser itself is nearly off-the-shelf. We currently don’t have any patents for the lasers, but there is a patent filed that’s related to the portable receiver — ways of making it more efficient. The laser is something that was built for us by one of our sponsors. It’s custom built, but using standard technology. Laser technology has become much more standardized and lower cost so that it is now cost effective for power beaming. Lasers have gone down in price and come up in power for laser welding applications or even laser hair removal. Oddly enough, laser hair removal is a big enough market to drive down the cost of lasers.
On the receiver side, the photovoltaics were custom built for us by Spectra Lab, which is a subsidiary of Boeing — one of our sponsors. It’s technology that they’ve already used, but they changed parts of it so the parameters are applicable to what we’re doing. Some of our “secret sauce” is in the integration of everything and all the lessons learned. There’s also some secret sauce in how the photovoltaic array is set up to maintain efficiency.
h+: What roadblocks do you anticipate in developing the technology?
TN: There are a number of obstacles. For us, as a company, right now the biggest obstacle is educating our customers. This is a new capability and people don’t think in terms of continuous electric power available from the ground. If you’re flying a UAV, you’ve got to have batteries or hydrogen fuel cells or jet fuel or gasoline or whatever. We’re trying to educate people that you could make your vehicle electric and power it all the time from 10 miles away with no wires. It’s a real challenge to communicate this so that people can grasp what it means in terms of new capabilities, new missions they can handle, and how it affects their logistics. Beyond that, we’re sitting on system efficiency at about 20%: from electrical power in on one end to electrical power out on the other end. But lasers have been getting more efficient. There’s a project that recently demonstrated much more efficient ones. The industry is slowly working its way towards that. On the photovoltaic receiver end, we’re still sort of stuck at about 50% efficiency and we’d really like to see research to boost that into the 70-80% range. So that’s another obstacle.
In general, in order to get some of the higher quality lasers, they’re not at wavelengths that are useful for getting sufficient receivers. Trying to get different photovoltaic and different laser technology so that you can transmit longer distances and still get the higher efficiencies is going to be another challenge.
Another big obstacle is going to be some of the regulatory framework. Actually, I shouldn’t say that it’s going to be an obstacle — things are going to have to change. In order to shoot a laser outside, we have to get permission from the Federal Aviation Administration (FAA) because they’re worried about pilots being blinded. The process they go through for approval is aimed at laser shows at rock concerts, which is a totally different behavior and environment than what we’ll be doing. Working with the FAA on some of the eye safety issues and how to authorize these types of applications is going to be a work-in-progress on updating regulations to be able to handle power beaming.
To get the higher power and try to focus it longer distances, you need the approval of the Laser Clearinghouse, to make sure you don’t blind satellites.
The regulatory obstacles are more at the national level. In order to get the higher power and to try to focus it longer distances, you also need the approval of the Laser Clearinghouse, which is part of the Pentagon, to make sure you don’t blind satellites. We had to get permissions from them for firing windows last fall: “no satellites in range right now, go ahead and fire.”
h+: Do you anticipate that LaserMotive will be involved in developing ground stations when you start beaming power from space?
TN: Absolutely. The ground station — we also refer to it as the photovoltaic array or receiver — is definitely a big part of the package we offer. We’ll definitely need to be involved in that.
h+: How will the power get transferred to the grid?
TN: It depends on where the location is. You’d presumably just run wires from the receiver to the grid. And because the lasers can be relatively narrowly targeted, you can have receivers that are not too far from the grid. You can easily shorten the distance. Right now, if you have a wind farm it has to be in the middle of nowhere, and you have a big problem getting that power onto the grid. With power beaming, you’d be able to receive it much closer to the grid.
h+: What health hazards do you anticipate?
The lasers we use are all Class 4 and they’re currently in the near infrared. This means that your eye can focus the light onto your retina, so they’re definitely an eye hazard. However, we keep saying that it’s not a death ray because the power density is higher than sunlight, but not that much higher. We’re operating at about 10 times sunlight. If you stick your hand in that beam, it’ll feel warm and you’ll want to take your hand out, but it wouldn’t cause any instantaneous burns or anything. We actually had our beam focused down to 100 to 200 times sunlight, and then we were able to cook a hot dog. But it took four minutes. So that gives you a sense that it’s similar to the power in your oven. Again, you don’t want to stick your hand in the path of a laser for any length of time, but it doesn’t cause instantaneous damage. So while it’s not a skin hazard, it’s an eye hazard. When we’re operating lasers we always wear safety goggles. As we build these systems, we’ll be incorporating safety systems to ensure that the beam is not on if anything gets close to the beam. You can have various communications between the transmitter and the receiver to make sure that the path is clear.
h+: You worked with Nathan Myhrvold on the use of laser “mosquito zapper” to help control malaria. Whatever happened with that project?
I’m not authorized to speak on behalf of Intellectual Ventures — but I can say that it’s still under development and they’re getting interest in it. It was lots of fun working on that project. Nathan did a presentation on it at the TED conference a couple of months ago. [Editor’s note: Here’s a short video from Intellectual Ventures showing a mosquito shoot-down sequence:]
h+: So you think the use of lasers is a viable approach to controlling malaria?
Oh yeah, there’s no doubt about it. There are commercial questions about how it gets developed and who gets it first, but technically speaking we’ve demonstrated that it’s certainly possible to do — and on a reasonable budget as well.
h+: Hey, one last question. Any good book recommendations? :+)
TN: (laughs) I’m too busy to read right now. In addition to trying to start up this company, I have two small children — a 2-year-old and a 6-year-old — so that’s keeping me very busy as well. The last book I read was John Ringo’s Live Free or Die I do enjoy science fiction. In general, I really like Terry Pratchett’s novels. I did take the 6-year-old to see the film How to Train Your Dragon. It was the first 3D movie she’d ever seen. It was fun to watch her reaction: she reached her hand out and said “it’s right there.”
Tom Nugent holds a B.S. in Physics from University of Illinois at Urbana-Champaign, and M.S. in Materials Science and Engineering from Massachusetts Institute of Technology.