Difference Between Energy Efficiency and Energy Conservation

能源效率与节能

Conservation of energy and energy efficiency are two important topics discussed under energy. These topics are highly significant in fields such as machinery, Astronomy, space exploration and even our daily lives. It is vital to have a clear understanding in these topics in order to excel in such fields. In this article, we are going to discuss what conservation of energy and energy efficiency are, their applications, definitions of energy conservation and energy efficiency and finally the difference between energy conservation and energy efficiency.

Conservation of Energy

Conservation of energy is a concept that is discussed under classical mechanics. This states that the total amount of energy in an isolated system is conserved. However, this is not entirely true. To understand this concept fully, one must first understand the concept of energy and mass. Energy is a non-intuitive concept. The term “energy” is derived from the Greek word “energeia”, which means operation or activity. In this sense, energy is the mechanism behind an activity. Energy is not a directly observable quantity. But it can be calculated by measuring external properties. Energy can be found in many forms. Kinetic energy, thermal energy, and potential energy are to name a few. Energy was thought to be a conserved property in the universe up until the special theory of relativity was developed. The observations of nuclear reactions showed that the energy of an isolated system is not conserved. In fact, it is the combined energy and mass that is conserved in an isolated system, because energy and mass are interchangeable. It is given by the very famous equation E = mc²where E is the energy, m is the mass and c is the speed of light.

Energy Efficiency

For hundreds of thousands of years, scientists and scholars are trying to build more efficient machines. The efficiency is simply how much we get for what we spend. Energy efficiency is the ratio of the useful work done by the system/input energy of the system. Let us take a simple light bulb. In this case, light is the useful energy of the machine, and what we input as electrical current is the input of this system. If the bulb is rated 100 watts and it produces light rays equivalent to 15 watts, the efficiency of the light bulb is 15/100. This can be given as a fraction (0.15) or a percentage (15%). The remaining energy is wasted as heat. Transformers are known as one of the most efficient machines ever built. The efficiency of a transformer can go up to 99%. It is impossible to make a machine or any process 100% efficient.

What is the difference between energy efficiency and energy conservation? • Energy conservation is a property of energy which allows it to change the type. • Energy conservation is a property of a machine which tells us the useful work done per unit energy input.