The world population is rapidly growing, with studies predicting a world population of 9 billion by 2040. This is an addition to of 1 billion people the already 8 billion people living on the planet today. This population will need energy, hence increasing the global energy demand. Further, in many countries the living standard is rapidly changing resulting to increased energy demand.
Today energy infrastructure heavily depends on fossil fuels such as oil, coal and gas. Fossil fuels are millions and millions of years of solar energy stored in the form of chemical energy. The problem is that humans deplete these fossil fuels much faster than they are generated through the photosynthetic process in nature. Fossil fuels are not a sustainable energy source.
The more fossil fuels we consume, the less easily available gas and oil resources will be. Already, we see that more and more oil and gas is produced with unconventional methods. Burning fossil fuels produce the so-called greenhouse gases like carbon dioxide (CO2). There are many primary sources of energy that can be converted into electricity for use in our homes, schools, offices and industries. These sources are however classified into two main groups, namely, non-renewable and renewable energy.