How do we define alternative energy ?
It is usually associated with a source of energy which is renewable.
We can regard a renewable energy source as having an unlimited supply of energy , since it is constantly being replenished as we convert the energy into other forms . Yet, a common error is to consider renewable energy as a source of energy that can be used 'again and again' . You can only use a given portion of the energy source once ! The energy does not go back straight into the source again. It is converted into other forms of energy. Eventually this energy is dissipated into the atmosphere. We could, for example, regard coal as being renewable. It all depends if we are prepared to wait for millions of years for the formation of other coal deposits. Yet the conditions that were present millions of years ago as the plants died and rotted are distinctly different from the conditions that exist today. Therefore, as far as we and future generations are concerned, there is only a limited supply of coal, oil and gas left for us to use.
There is another downside of the use of non-renewable energy sources. They need to be burnt in order to convert the chemical energy into the useful forms that we need. Unfortunately , the burning of coal at a power station results in the emission of carbon dioxide and sulphur dioxide. Vast quantities of carbon dioxide are adding to the Greenhouse Effect, and the sulphur dioxide provides a source for the formation of acid rain .
What can we do to extend the lifetime of the non-renewables ? We can help by saving energy at home, by insulating our homes, by using more efficient electrical appliances, and by using public transport instead of travelling around in our own personal transport . In addition, we can convert more of the renewable energy sources into the energy that we need in everyday life, such as electricity, and moving our vehicles.
Yet the use of alternative sources of energy can also be interpreted as being another source of pollution . The numbers of wind turbines that would be needed to replace one fossil-powered station are regarded by many people as providing visual pollution, and spoiling the natural beauty of the landscape. Then there is the cost and use of the land, and the fact that the air movement is variable and that demand for energy would not always be matched by the ability to supply.