Previously, the POWER system managed to use a laser to beam 230 watts across one mile (1.7 km) for 25 seconds, and an undisclosed lesser amount of power as far as 2.3 miles (3.7 km). Now, DARPA has managed to increase this to 800 watts for 30 seconds at a distance of 5.3 miles (8.6 km).

I wonder what the maximum theoretical efficiency is. The article says the current system is 20% efficient, which is not exactly good. I’m not a physicist so take this all with a grain of salt. They’re going to have to overcome generation losses (this article says diode lasers can be 60% efficient but have Problems™), transmission losses (the inverse square law is a bitch, and they’ll have to contend with atmospheric absorption and scattering), and receiving losses (they’re using PVs which are famously not super duper efficient). I’m sure they’re working on all of this, and it seems reasonable that you might be able to get power transmission up to, say, 50% efficiency. That’s great and has its uses, but it’s not going to replace transmission lines, batteries, solar panels, and gas generators. Plus, we’re talking about sending 10 kilowatts of power across 200 km via light. Can you imagine how dangerous that would be? Like, what happens to anything in the path of that laser beam? What happens if the light gets reflected? a 10kW CW laser is no fucking joke!

EDIT: I could see this being useful for recharging/powering drones or something. It also seems like it would be much more useful in space where atmospheric scattering becomes a nothing burger.