Everything runs on energy. This includes all living things, as well as all the cars, houses, factories, lights, and appliances on which we depend. Every unit of energy we use costs us something, be it money or some other type of resource. So whenever we waste energy, we waste money or resources or both.
This is why we need to care about using energy more efficiently. Probably every one of us wastes energy in some way: by driving vehicles with a low fuel efficiency (getting less than 40 miles per gallon); living in poorly insulated houses; using energy-inefficient lighting and appliances; or leaving lights and computers on or motors running when we are not using them. Also, because our use of energy often has harmful effects on the environment, the more energy we waste, the greater is our ecological footprint.
We should also care about the sources of the energy we use. The use of any energy resource has an environmental impact. But our most widely used energy resources—nonrenewable oil, natural gas, coal, and uranium (which fuels nuclear power plants)—have large harmful environmental impacts. By shifting during the next several decades to greater use of renewable energy from the sun, wind, flowing water, and geothermal energy stored as heat in the earth's crust, we can greatly reduce these harmful environmental impacts.
When we rely more on renewable energy sources, most of which depend on energy from the sun, we are following one of nature's three scientific principles of sustainability that have sustained life on the earth for about 3.5 billion years. Some scientists argue that by following these principles, we will have a better chance of preserving our species, cultures, and economies than we will if we ignore them.
There is a great deal of evidence that certain human activities, in violation of these principles, are degrading the earth's life support system. In these activities, we are wasting huge amounts of energy and relying on environmentally harmful energy resources. The good news is that, by observing the earth's scientific sustainability principles, we can still enjoy many of the benefits of today's affluent societies without wasting so much energy and money, and we can reduce our harmful environmental impacts.
