The substances that we as human beings classify as 'pollutants' have always been present on the planet, because the earth is a closed system. The reason that these materials cause a negative impact on the environment, therefore, is not that they exist, but that they have been dispersed throughout the world's ecosystems in a very disordered fashion. To illustrate this, two pollutants of major concern will be considered, carbon dioxide (CO2) and sulphur dioxide (SO2). CO2 and SO2 are both given off when coal is burned to provide heat or to generate electricity. CO2 is the most important greenhouse gas contributing to global warming, and SO2 is the main cause of acid rain. Carbon and sulphur have no impact on the environment when they are locked up in the highly ordered form of coal. It is when fossil fuels are burned, and the combustion products are released into the atmosphere, that these compounds become pollutants.
Renewable Energy, The Entropy Solution?
From the facts listed above, solar energy can be used to counterbalance increases in entropy caused by the use of fossil fuels. As long as the rate of entropy increase due to fossil fuels is less than the rate of entropy decrease from solar radiation, the net entropy on the planet will not increase. Since the amount of solar radiation reaching the earth is quite large, why can't humans continue to use vast quantities of fossil fuels? It is virtually impossible to channel solar radiation such that it can counteract the negative impact of pollution caused by fossil fuels. For example, it is difficult to imagine using the sun's energy to reduce the acidity of lakes and forest soils damaged by acid rain. A better solution, would be to use solar radiation to power our societies directly. This would be more efficient than using fossil fuels to create our highly ordered civilizations, and then trying to eliminate the pollution and entropy by using sunlight. Renewable energy technologies such as solar energy (photovoltaic cells, active and passive solar heating etc.), biomass (plant matter), wind power and hydro power use sunlight either directly or indirectly, to produce the high quality energy demanded by industrialized societies.
The entropy or disorder of the universe is constantly increasing with time. Fortunately, the earth is not an isolated system like the universe, and we can maintain entropy on the planet, as long as the sun continues to shine. Despite this fact, humans are consuming energy from fossil fuels at such a pace that entropy is increasing. In order to reduce this increase in entropy, humans must reduce the amount of energy they use, and obtain this energy from the sun rather than fossil fuels.