Glossary letter W

Waste Heat

Like waste energy, waste heat is heat whose release during a process or the manufacture of a product is unavoidable. This heat dissipates naturally, but in some cases can be partly recovered and used. It can also be reduced. Waste heat falls into the same category as the heat releases associated with many common processes and actions. These include residential wastewater; cooling water, air conditioning and drying; defective insulation and doors and windows left open in cold weather; combustion gas from furnaces, boilers, incinerators and engines; product cooling by the glass, metal, cement and brick industries; and the heat radiated in steelmaking.

Water Energy

Energy generated by the movement of water in a liquid state, including waterfalls, lakes, rivers, marine currents and waves. The kinetic energy of moving water is converted into electricity.


The watt (symbol W) is the derived unit of power (see definition) in the International System of Units (SI). A watt equals one joule per second (1 W = 1 J/ s-1) of energy converted or transferred. Two multiples of the watt are used more commonly: the kilowatt (kW) and, for high-capacity power plants, the megawatt (MW).

Wave Power

Wave power involves capturing the energy of ocean waves to generate electricity. The first grid-connected commercial wave power plant came on stream in Australia in 2015.

Well (Borehole)

Cylindrical hole drilled into the subsurface. Wells are used to explore and produce oil and gas, tap deep geothermal resources and produce water from aquifers.

Well Logging

Taking detailed physical measurements while drilling wells. The data are recorded using instruments lowered into the borehole by cable. These logging tools transmit an electrical or nuclear signal through the rock and the return signal is detected by a receiver. Processing the return signal provides data on the properties of the subsurface formations and their oil and gas saturations.



Complex system of valves found at the surface termination of boreholes and production wells and used to control the well effluents.

Wind Energy

Energy derived from the wind. Wind power involves converting the kinetic energy of moving air (wind) into electricity.

Wood fiber

Wood fiber is a component of wood and is characterized by its rigidity. In the industrial sector, the term "wood fiber" is used to refer to a raw material derived from trees or woody plants (i.e., plants that contain a sufficient quantity of vascular bundles to impart a rigid quality comparable to that of wood).

World Health Organization (WHO)

The directing and coordinating authority for health within the United Nations system. It was founded on April 7, 1948 for "the attainment by all peoples of the highest possible level of health." The WHO's Constitution defines health as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity."