ENERGY

Energy Source

Energy can be classified into two groups: primary and secondary, of which primary energy (e.g. fossil fuels) is transformed through energy conversion processes to secondary energy, such as heat energy, electrical energy or energy in other forms (e.g. refined fuels). The primary energy sources can be renewable or nonrenewable with the latter remains the dominant source of energy today.

Non-renewable Energy

Coal, petroleum, natural gas, propane and uranium are nonrenewable energy sources. These energy sources are called nonrenewable because their supplies on Earth are limited. Petroleum, for example, originated from the remains of ancient sea plants and animals, and it takes millions of years of natural processes to produce it, making it unlikely to be produced in a short time. Amongst the non-renewable energy sources, coal is the number one energy source for generating electricity in the world nowadays due to its low price.

Renewable Energy

Renewable energy sources include biomass, geothermal, hydropower (including tidal), solar and wind. Such energy sources are called renewable energy sources because they can be replenished from time to time and the impact to the natural resources is minimal. Currently, these renewable energy sources are primarily used in the electricity generation.