Energy is essential. It is embodied in everything we use. To compare sources of energy effectively, we need to understand what it is and how it works.
What is Energy?
It comes from many sources and in many forms. The forms of energy are classified in two general categories: potential and kinetic.
Potential energy is energy stored in an object. Chemical, mechanical, nuclear, gravitational, and electrical are all stored energy. Kinetic energy does the work. Light, heat, motion, and sound are examples of kinetic energy.
Here’s a simple example. Stretching a rubber band gives it the potential to fly. The tension created from the stretching is potential mechanical energy. When the rubber band is released, it flies through the air using motion (kinetic energy). The process of changing energy from one form into another is called energy transformation. The rubber band is transformed from potential energy into kinetic energy.
Systems convert energy at various rates of efficiency. Water turbines, for example, are very efficient, while combustion engines are not. Engineers and physicists constantly work to develop systems with high energy-conversion efficiency.
Which Energy Source is Best?
It depends. Many alternative sources of energy are still being researched and tested. Technologies are continually being developed and enhanced to improve energy sources. Not all energies are ready for mass consumption, so you have to ask the right questions to find out which energy source does the job.
- Is it a renewable or nonrenewable source?
- What are the capital and setup costs?
- What are the ongoing operating costs?
- What size of energy storage is required?
- How efficient is it to produce one unit of energy?
- Can it be produced on a large scale?
- What is the cost to the consumer?
- What impact will it have on the environment?
Energy is lost to the environment during any energy transformation, usually as heat. Notice the heat from your computer or car after it has been in use for a while. Nothing is completely energy efficient.
What are the Sources of Energy?
Primary energy sources (meaning energy is created directly from the actual resource) can be classified in two groups: nonrenewable or renewable. Secondary sources are derived from primary sources.
Non-Renewable Energy Sources – Energy from the ground that has limited supplies, either in the form of gas, liquid or solid, are called nonrenewable resources. They cannot be replenished, or made again, in a short period of time. Examples include: oil (petroleum), natural gas, coal and uranium (nuclear). Oil, natural gas and coal are called “fossil fuels” because they have been formed from the organic remains of prehistoric plants and animals.
Renewable Energy Sources – Energy that comes from a source that’s constantly renewed, such as the sun and wind, can be replenished naturally in a short period of time. Because of this we do not have to worry about them running out. Examples include: solar, wind, biomass and hydropower. Currently, about 20% of the world’s electricity comes from renewable resources. There is a global debate as to whether geothermal energy is renewable or nonrenewable.
Secondary Energy Sources – Energy that is converted from primary sources are secondary sources of energy. Secondary sources of energy are used to store, move, and deliver energy in an easily usable form. Examples include electricity and hydrogen.