Researchers Working On Lasers That Transmit Electrical Power

A picture illustrating the wireless power transmission technology / Shutterstock. U.S. military researchers are asking the industry to devel...

A picture illustrating the wireless power transmission technology / Shutterstock.

U.S. military researchers are asking the industry to develop free-space laser power networks able to transmit electrical power over webs of lasers using aircraft as receivers and relays of optical energy. Officials of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., issued a Small Business Innovation Research (SBIR) opportunity (HR001121S0007-29) on Thursday for the Breakthrough Technologies for Energy Web Dominance project.

“The ability to safely transfer power across distances without having to be connected to the power grid eliminates one of the big obstacles we have when building new cell sites,” “The time savings and flexibility will make this technology an attractive solution.”

A wireless network energy web that consists of several dynamic nodes will improve military capabilities significantly, DARPA researchers say. To achieve this, researchers are interested in three technology areas: high-energy-flux; high-efficiency optical energy conversion; and relay technologies. The goal is to develop safe optical power-beaming web networks with links that provide rigorous photon containment and intrusion monitoring to ensure optical energy goes to the intended receiver without harming human bystanders or objects.

Such an energy web network consists of ground laser sources providing power to airborne nodes that use this power for own-ship requirements through conversion, and then relay the remaining power without conversion to other energy web nodes. 

Designs should support low size, weight, and power (SWAP) for the airborne portions of the power beaming system. Traditional photovoltaic power beaming loses efficiency at high energy fluxes due to high temperatures, researchers explain. Although conversion methods such as thermoelectrics are one approach to achieving higher energy fluxes, they typically have poor efficiency.

The DARPA Breakthrough Technologies for Energy Web Dominance project seeks to optimize system efficiency by accounting for cooling losses for systems with an energy flux of 1 kilowatt per square meter, and scalable to 100 kilowatts per square meter or more. Relays are elements of the optical chain that retransmit optical energy without first converting it back to electricity. These optical waveguides could be as simple as a mirror, but likely will involve several components to redirect power flexibly to intended receivers.

Relays must demonstrate high efficiency and beam quality while accounting for losses such as fiber coupling inefficiencies and wavefront aberrations from turbulence in the propagation path. Proposals should address ways to correct beam aberrations or mitigate losses in optical chain relays. Safety also is a big concern. Wireless beaming of optical energy will require at least 10 to 100 kilowatts of sustained beamed optical power. These power levels are inherently dangerous and pose substantial systems design challenges, particularly for dynamic platforms operating in real-world environments.

Nikola Tesla proved it 100 years ago / Shutterstock.

Of particular concern is the danger to bystanders who may be subject to “splash” glints or “spillover” reflections that are inadvertently directed toward unintended locations. DARPA researchers are looking for technologies that substantially address these safety concerns through rigorously assured photon containment. Low-SWAP solutions also must provide continuous path monitoring to detect and react to mobile intruders into the beam.

Any proposed method of assured photon containment may tackle a portion of the overall problem. One solution might involve sensing glints over a nearly spherical field of regard. Another might design surface morphologies that capture reflections, antireflective, coatings or absorptive surfaces.

Rigorously assured photon containment provides a probability of less than one in one billion likelihood of unintended radiation emission at irradiance levels exceeding 5 milliwatts per square centimeter that are capable of reaching human subjects if below wavelengths of 1.4 microns. If above 1.4 micron irradiance levels should not exceed 100 milliwatts per square centimeter.

Enabling technologies from this project aren't just for military applications. The systems required for efficient power beaming can be applied to many other applications such as free-space laser communications, high-energy laser propagation, LIDAR, or other high-pulse-energy or continuous power laser applications. Optical systems with high tolerance for thermal loads also may be applied to systems that operate in challenging environments involving nearby sources of heat.

Russian Space project / TASS.

On Another Hand

Russian Military Space Academy experts introduced the power refueling satellites. Russia is developing a "space gas station" - a group of robots that will use lasers to recharge satellites in near-Earth orbit, say experts at the Alexander Mozhaysky Military Space Academy in St. Petersburg. The prototype for the planned spacecraft is a spherical object, with solar panels and photovoltaic modules.

Such a robotic structure will be fitted with batteries and a pulse charger based on a supercapacitor, capable of accumulating and transmitting electrical energy to orbiting satellites by laser. The robotic group will be tasked with ensuring the smooth operation of the small spacecraft belonging to the international search and rescue system Cospas-Sarsat, as well as satellite transponders for Internet, video and radio communications.

China has announced plans to launch a fleet of solar panels into space that will beam the solar energy collected back to earth. The power plant, set to launch by 2035, will convert solar energy into laser or microwaves that will be sent back to earth. Being set in space means it can avoid the problems created by the fluxes of weather, clouds, day and night – exactly the kinds of problems faced by the UK recently. Beams of energy will be fed back to the receiving station in Chongqing which converts them to electricity for the grid.

Wireless electricity startup company,Emrod / Getty Images.

Researchers in the US are making similar advances towards such a reality, the technology of which was dreamed up more than 100 years ago by Nikola Tesla. Having designed the Tesla Coil, a device that transmitted energy without wires, he worked on an energy station that could transmit energy across long distances using strategically placed towers.

New Zealand company, Emrod, is innovating in the field of energy transmission by using a network of antennas to move energy around the country without wires. Long-range electromagnetic waves are transmitted from place to place via the antennas. The use of lasers in the technology shuts down the transmission when it detects an object, such as a helicopter.

Technology like this solves many of the problems raised by renewable energy. It allows for the generation of electricity regardless of weather conditions and harsh terrains, as well as making possible the wireless transmission of energy on a large scale. This could open up doors for energy accessibility much more broadly, and be used to move it to places where it is needed quickly and viably.

The problems posed by sustainable energy are significant, but they are certainly not unsolvable. The innovations the world has seen over the last couple of years present solutions that will allow not only better generation, storage and distribution of energy, but will create a world around it that is much more efficient and effective in its processes. These are the innovations that will make an environmentally and economically sustainable future possible and will truly and effectively bring power to the people.