Scientists define energy as the ability to do work. We have learned to change energy from one form to another, to use it to do work.
Different forms of energy exist, including:
There is also a multitude of sources of energy, which can be split into two basic categories:
Renewable energy sources, which can be easily replenished (biomass, hydropower, geothermal, wind, solar, nuclear energy*)
Nonrenewable energy sources, which cannot be easily replenished (petroleum, hydrocarbon gas liquids, natural gas, coal)
*Nuclear energy can sometimes be considered by companies as renewable, so use your critical judgment when reporting their figures.
Companies consume energy, often electricity, throughout their operations, products and services.
All forms of electricity generation and consumption have an environmental impact on air, water and land, but it varies depending on the type of energy and quantity.
Energy vs Electricity
As you look through a company’s report, they will often state their electricity consumption, especially renewable electricity consumption. Keep in mind that electricity is only one part of their energy consumption. For example, the company may report that they use 50% renewable electricity, but you may find that only 15% of their total energy consumption is renewable.
Energy vs Power
Energy is the “quantitative property that must be transferred to an object in order to perform work on, or to heat, the object”. In other words, it describes the quantity of work needed to perform a particular task.
Power is an “amount of energy transferred or converted per unit time”. In other words, it describes how fast a task can be done.
For example, a typical windmill delivers 3 megaWatt (MW) = 106 W. During one hour at full power, it will have produced 3 MW x 1 hour = 3 MWh (Energy = Power x Time)
Thus, energy units: GJ, Watt Hour (Wh, kWh, MWh and further multiples)
Power units: Watt (W, kW, MW and further multiples)