1. Pull the iPhone out of the pocket (if it's not already in your hands).
2. Shake the iPhone
3. Follow the steps in this picture.
You can also try solar powered panels which will use the sun's rays to illuminate the servers and make them more efficient in summer.
To save on costs, you can always use renewable sources of energy like this.
"Consider a spherical bear, in simple harmonic motion..." -- Professor in the UCB physics department