Petroleum contributes to electricity generation as a thermal fuel source, requiring combustion to release its stored energy. This process occurs in large industrial facilities called thermal power plants. The operation involves a chain of energy transformations, starting with the oil’s chemical energy. This energy is converted sequentially into heat, mechanical energy, and finally, electrical energy transmitted across the power grid.
Converting Chemical Energy to Heat
The process begins when heavy fuel oil, refined from crude oil, is prepared for combustion. The oil is pre-heated to reduce viscosity, allowing it to be atomized into a fine mist for efficient burning. This atomized oil is injected into a furnace or boiler, mixed with pre-heated air, and ignited.
The combustion reaction is exothermic, breaking hydrocarbon bonds and releasing a massive amount of thermal energy. Temperatures inside the chamber often range between 1,200 and 1,400 degrees Celsius. This intense heat is the primary output of the first stage.
The furnace walls are lined with extensive networks of water-filled pipes that function as heat exchangers. Scorching combustion gases circulate around these tubes, rapidly transferring thermal energy to the water inside. This heating converts the liquid water into high-pressure steam, often exceeding 150 bar, which drives the next stage.
Harnessing Steam to Drive Turbines
The superheated, high-pressure steam is channeled into the steam turbine, designed to capture the energy of the expanding gas. The turbine consists of a series of blades mounted onto a central rotating component called the rotor.
As the steam enters, it is directed through nozzles that accelerate its velocity before striking the specialized blades. The steam expands rapidly across multiple stages, causing a drop in pressure and temperature. This expansion transfers the steam’s kinetic energy directly to the blades, causing the rotor assembly to spin at high speeds.
This continuous push generates a powerful rotational force, or torque. The steam’s kinetic energy is effectively converted into the mechanical energy of the spinning shaft. Maximizing this energy transfer ensures the shaft spins consistently, providing the necessary rotational input for the final stage.
The Final Step Generating Electricity
The mechanical energy from the spinning turbine is immediately used by the electrical generator, or alternator, which is directly connected to the shaft. The generator converts rotational motion into usable electrical energy, relying on electromagnetic induction.
The generator has a rotating rotor and a stationary stator. The rotor contains powerful electromagnets spun by the turbine shaft inside the stator, a large coil of copper wiring. As the rotor’s magnetic field sweeps past the stator’s conductors, it creates a constantly changing magnetic flux.
This change induces an electromotive force, causing electrons to flow and generating an electric current. The resulting alternating current is then conditioned and stepped up in voltage for efficient transmission across the power grid.