One way to decrease greenhouse gas emissions associated with streaming music is making data centers carbon neutral, by converting to electricity produced from renewable sources. On an individual level, purchase of a physical CD may be more environmentally friendly if it is to be played more than 27 times. Another option for reducing energy use can be downloading the music for offline listening, to reduce the need for streaming over distance. The Spotify service has a built-in local cache to reduce the necessity of repeating song streams.