# Would this work as a way to get more energy from sunlight? [closed]

Plants only absorb certain wavelengths of light. This leaves a lot of light useless. But... imagine putting plants on a wheel and spin that wheel very fast. Then the light is red-shifted and so the plants can absorb a different color of light.

Likewise one might do the same trick with solar panels.

So imagine a scenario where the sun is emitting red light. But a solar panel could only absorb blue light.

Is this possible to use this trick to make the solar panel work? (Assume it is in a frictionelss environment). And how fast would you have to move the solar panel?

As more practical example(?), maybe one could have a ionised gas whose atoms only absorb a certain frequency. But then that gas is rotated very fast in a magnetic field so that now the atoms can absorb the sunlight because of redshifting). Not sure if the energy could be harnessed from this!

• Have you tried applying Doppler shift equation here? Oct 8, 2019 at 2:14
• @Aaron I am not familar with the equation. I'll take a look. From the word Dopler I feel like the answer is that you'd have to move it close to the speed of light! Oct 8, 2019 at 2:17
• Also note that plants have adapted to absorb light at the peak of the sunlight spectrum, I believe. Oct 8, 2019 at 2:17
• @aaron yes, but that still leaves a fair bit not used. e.g. all that green light that is reflected to make plants look green. Oct 8, 2019 at 2:18
• 'course if you red shift the light, then the light it used to be gathering is now out in the longer wavelengths and not being absorbed in a useful way. Oct 8, 2019 at 4:56