Resources can be divided into two categories: renewable and non-renewable.
Renewable resources can be easily replaced after they are used. For example, sunlight, wind, beef, corn, and water.
Non-renewable resources are very difficult, if not impossible, to replace once they have been used. Examples include gold, diamonds, coal, oil, natural gas, and copper.
Currently, there is a big push for the development of new and/or improved methods for harnessing the power of renewable resources to power automobiles and electrical grids around the country and world. This is because the population is quickly realizing that petroleum based products, like gasoline, will eventually run out. This has been largely affected by the sudden spike in fuel prices and the growing awareness of our role in global warming.