The learner knows that some of Earth's energy resources are available on a nearly perpetual basis, while others can be renewed over relatively short period of time. Some energy resources, once depleted, are essentially nonrenewable. The learner is expected to:
Nonrenewable resources that cannot be replaced easily.
Renewable energy sources are an alternative to fossil fuels or nonrenewable sources. They are a better alternative to fossil fuels because they do not damage the environment with greenhouse gases like the nonrenewable sources.