Photo Credits

Coal Photo – Paul Downey
https://www.flickr.com/photos/psd/

Hydroelectric power plant Photo - Chalisa jirutchok
https://commons.wikimedia.org/wiki/File:Hydro-energy.jpg

Wind Turbines Photo – Leaflet
https://commons.wikimedia.org/wiki/User:Leaflet

Solar Panels – Public Domain
http://www.publicdomainpictures.net/view-image.php?image=9099

Ocean Oil Platform  – Public Domain, US Gov
 https://commons.wikimedia.org/wiki/File:PlatformHolly.jpg

Natural Gas Photo – Public Domain
https://commons.wikimedia.org/wiki/File:Natural_gas.jpg