**3. Energy conversion**

Energy conversion involves transforming one form of energy into another to meet specific energy needs and applications. According to the first law of thermodynamics, energy can be transformed into different forms, but it cannot be created or destroyed [3]. Mechanical, chemical, thermal, optical, and electrical energy conversion processes take place around us all the time. Car engines transform chemical energy into mechanical energy. Solar panels convert optical energy directly into electricity. Space heaters convert electricity into thermal energy. LED bulbs convert electricity into optical or light energy.

Among these energy conversions, the conversion of various forms of energy into electricity is particularly interesting because electricity is as important as water and food to people in the modern era. Electricity is used for heating, cooling, and lighting and for operating cell phones and appliances in our daily lives. There are many different types of electric generators. The vast majority of electrical generators are based on Faraday's law of induction discovered in 1831 [4]. Other types of electrical generators include photovoltaic cells, fuel cells, and thermoelectric generators. Photovoltaic cells convert solar energy directly into electricity through the photovoltaic effect. Fuel cells produce electricity through an electrochemical process wherein a hydrocarbon fuel reacts with oxygen. A thermoelectric generator is composed of p- and n-type semiconductor legs that convert thermal energy directly into electricity through the Seebeck effect.

Renewable energy such as solar, wind, and geothermal energy has become one of the fastest growing sources of electricity generation around the world. Enhancing the efficiency and sustainability of energy conversion processes is critical for reducing greenhouse gas emissions, minimizing resource depletion, and mitigating environmental impacts.
