In these light blue pipes flows energy. Energy, or the ability to do work, is necessary for everything from plants performing photosynthesis to you chewing your lunch. It can come from many sources, including the Sun, wind, flowing water, and fossil fuels, and in many forms. While energy cannot be created or destroyed, however, there is a fast-approaching limit on how quickly humans can keep using up energy sources like oil and coal. In this chapter, you will learn about how energy comes to be stored in those forms and about energy alternatives that are sustainable for the future.
Image copyright cobalt88, 2013. www.shutterstock.com. Used under license from Shutterstock.com.