The frequency-response reserve (also known as regulating reserve) is provided as an automatic reaction to a loss in supply.

Greater loads physically slow the rotors of a grid's synchronized generators.

In physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency, rather than time.

A frequency counter is an electronic instrument, or component of one, that is used for measuring frequency.

An electromechanical device that converts alternating current of one frequency to alternating current of another frequency.

Frequency is the number of occurrences of a repeating event per unit of time.

Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point.

In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress, such as the interface between two homogeneous fluids, for example liquid water and the air in the Earth's atmosphere.

Free energy suppression is a conspiracy theory that technologically viable, pollution-free, no-cost energy sources are being suppressed by government, corporations, or advocacy groups.

Free cooling is an economical method of using low external air temperatures to assist in chilling water, which can then be used for industrial processes, or air conditioning systems.

The Francis turbine is a type of water turbine that was developed by James B.

Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials.

Fracture is the separation of an object or material into two or more pieces under the action of stress.

This class of biofuels includes electrofuels and solar fuels.

Four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements than the simpler and more usual two-terminal (2T) sensing. The technique is called Kelvin sensing.

A four-stroke engine is an internal combustion engine in which the piston completes four separate strokes while turning the crankshaft.

The rate at which the heat transfer surfaces in a boiler become fouled. Fouling occurs due to the exhast gases passing over heat transfer surfaces.

Naturally occurring organic fuel produced in the earth such as oil, gas and coal. Fossil fuels were produced billions of years ago and are expensive to extract from the earth. Fossil fuels are non renewable and when burnt for energy are damaging to the environment in producing carbon dioxide.

A poer station that burns fossil fuels such as natural gas or coal to produce electricity.

The process to reduce the use of fossil fuels to zero. Also know as renewable energy transition.