Energy transmission by laser – the solution for the Earth’s future energy supply?
The issue of global warming is of concern to all. Reduction of energy consumption is an important factor but still it will not bring the additional energy needed for developing populations without increasing the effect of global warming.
The root cause of this warming effect is that, in the conversion to electricity, all of our current energy sources release around 50% in heat into the atmosphere plus some greenhouse gases and other unwanted particulates. The quest to find a long-term solution to providing power which does not increase the heat and gas rejected in the atmosphere is becoming urgent.
The solution Airbus Defence and Space has come up with is to extract energy from the solar flux available around the Earth and convert it in space into a beam of infra-red energy pointed to a highly efficient receiver. The key difference here is that the conversion losses from solar flux to infra-red beam (25% multispectral solar cell efficiency and 50% efficiency in conversion to laser) would be dissipated in space and therefore would not affect the Earth.
In terms of impact on the environment, therefore, only the conversion from light to electricity (the best for narrow band photovoltaics is currently around 50%, but could be up to 80% in the future) needs be considered.
What about the safety of high energy beams?
We have selected energy transmission at an infra-red wavelength of 1.5 microns because at that wavelength we can transmit up to 1,000 W/m² to ground safely. This is comparable with normal sunlight at 1,300 W/m² with no dust or atmospheric losses. A human passing through such a beam would receive as much heat as if he were exposed directly to the sun, but without the secondary effects of UV contained in the sunlight. Any other object or animal would also be able to safely cross the 1.5 micron beam.