DARPA program sets distance record for power beaming

Comparison to conventional power transmission

• Multiple comments stress this is nowhere near a replacement for HVDC: 800 W over ~5 miles vs grid-scale megawatts over thousands of miles.
• End-to-end efficiency is described as “atrocious” compared to 90%+ for HVDC, so only suitable where efficiency is unimportant (e.g., military).

Efficiency, physics, and heat

• Reported ~20% optical-to-electrical efficiency, with estimates that electrical→laser could be 25–50%, implying tens of kilowatts in for hundreds of watts out.
• Debate over photovoltaic efficiency under monochromatic lasers: some argue limits around ~27%; others cite research cells at ~70% with potential for more when carefully bandgap-matched.
• Several note that higher laser power means significant concentrated waste heat on the receiver, with risk of thermal runaway as PV cells heat up and lose efficiency.

Potential applications (drones, space, sensors)

• Strong focus on drones: topping up or continuously powering long-endurance drones is seen as the clearest near-term use.
• Ideas extend to powering aircraft, satellites, deep-space probes, and dormant or buried instruments that are “woken up” by brief high-power beams.
• Some propose combining power and data in the same beam; others suggest this tech is useful mainly when refueling/rewiring is impossible.

Safety and environmental concerns

• Concerns about birds, people, and satellites intersecting a powerful “invisible” beam; reflection from shiny objects could cause eye injuries at long distances.
• Suggestions include use only at high altitude, restricted test ranges, virtual safety enclosures, or multiple low-power beams that only sum to high power at the receiver.
• There is skepticism that real-world actors (especially military or corporations) will adequately “engineer around” safety risks.

Atmosphere, weather, and test conditions

• Discussion of why tests were done in dry New Mexico: deserts match many deployment environments and reduce humidity losses.
• Others argue a truly “maximum impact” test would use fog or high humidity (e.g., Florida), where water vapor would severely attenuate the beam.
• Some mention turbulence and convection in deserts causing beam spread and the likely need for adaptive optics.

Skepticism, enthusiasm, and speculation

• Some see the project as a disguised weapons program or a way to burn budget; others are genuinely excited by any progress in wireless power.
• Speculation branches into weather modification via microwaves, which is largely dismissed as energetically unrealistic.
• Side discussions touch on nuclear-powered drones, nuclear batteries, and historical DARPA-style “weird ideas” as context for this work.