Energy is the greatest challenge facing humanity in the 21st century. This course will cover the historical aspects of energy conversion and use by humans, the types of energy available (including both renewable and non-renewable), their conversion to useful forms of energy, conversion efficiency, and cost of conversion. A very important aspect of the course is the environmental effect of energy conversion. The atmospheric pollution by greenhouse gases as well as conventional pollutants during energy conversion will be discussed. The main methods of pollution reduction by power industries will be presented.