Generating Electricity (Leaving Cert Construction Studies): Revision Notes

Generating electricity

Introduction

Electricity powers most modern home services and provides us with essential comforts. Understanding how electricity is generated is crucial before exploring its uses in the home.

Electricity generation in Ireland has evolved significantly since the late 19th century. The methods have become more reliable and efficient over time. Since 1990, there has been a notable shift in energy sources - the use of coal and peat for electricity generation has declined, oil usage has increased, and from 2006 onwards, renewable energy sources have begun to play a larger role.

Types of power stations in Ireland

Ireland generates electricity using four main types of power stations:

• Fuel-burning power stations
• Wind farms
• Hydroelectric power stations
• Pumped storage systems

Fuel-burning power stations

Fuel-burning power stations represent one of the oldest commercial methods for producing electricity. These facilities burn raw materials including coal, peat, oil, or gas to harness heat energy and convert it into electrical power.

The generation process follows a clear sequence. When fuel burns, it produces heat that transforms water into steam. This pressurised steam flows through a turbine, causing it to spin rapidly. A large dynamo connected to the turbine converts the mechanical spinning energy into electricity. After passing through the turbine, steam is cooled in cooling towers before returning to the boiler to repeat the cycle.

These power stations typically locate near large water bodies like lakes or rivers to ensure adequate water supply for the steam generation process. Modern fuel-burning stations have improved significantly with better health and safety controls, environmental protections, and systems to clean harmful emissions before they enter the atmosphere.

Wind farms

Ireland's abundant wind resources, particularly along western and southern coasts, provide excellent opportunities for wind power generation. Traditional windmills have harnessed wind energy for centuries, as seen in restored 19th-century examples like the windmill at Blennerville, Co. Kerry.

Modern wind turbines operate differently from fuel-burning stations. Instead of using steam, they harness prevailing winds to turn large rotor blades. These blades connect to an electromagnetic generator - a rotating mechanical device that converts wind energy directly into electrical energy.

Wind turbines operate effectively only at relatively low speeds. Therefore, wind farms consisting of multiple turbines connected to a central collection station are necessary to generate substantial amounts of electricity. Wind farms use renewable energy sources with minimal environmental impact compared to fuel-burning alternatives.

Critics highlight concerns about noise levels and visual impact on natural landscapes. Despite these issues, wind farms have become increasingly popular in Ireland due to the country's excellent wind energy potential.

Hydroelectric power stations

Hydroelectric power harnesses water as an energy source. While mills have used water power for centuries to operate grain crushing and machinery, modern hydroelectric stations introduce electrical generation capabilities.

A hydroelectric power station creates an artificial dam to trap large volumes of water. The controlled water flow passes through turbines, converting the water's potential energy into electrical energy. Ardnacrusha, built on the Shannon in Co. Clare, serves as Ireland's largest river hydroelectric scheme and demonstrates this technology's effectiveness.

Traditional water wheels, like those at Letterkenny, Co. Donegal, show how communities have historically captured water's kinetic energy for practical purposes.

Pumped storage systems

Pumped storage plants combine hydroelectric principles with energy storage capabilities. These systems use water's potential energy but operate on a cyclical schedule to match electricity demand patterns.

During night hours, when electricity is most abundant on the grid, water is pumped to a high-elevation reservoir. During daytime periods of increased electricity demand, this stored water is released through turbines to generate electrical energy. This daily cycle repeats continuously.

This approach allows greater control over electricity production timing. Some pumped storage systems work alongside wind farms - the wind energy powers the pumps that move water to the reservoir, and the subsequent hydroelectric process sells energy back to the grid when needed.

National grid distribution

Power stations across Ireland supply the country's electricity needs, but this energy must travel from generation sites to towns and cities through the national grid system.

The national grid, operated by EirGrid, supplies electricity throughout the country. Transmission System Operators (TSOs) manage and maintain the national electricity transmission network. The TSO sells electricity to private companies at wholesale prices, and these private companies distribute the electricity and associated costs to households.

Electricity travels at high voltage from generation sources to local substations. High voltage transmission with low current prevents energy loss over long distances - energy dissipates as heat when electricity passes through cables, and higher voltages ensure more efficient energy delivery.

At local substations, transformers reduce the voltage for safe domestic and commercial use, typically to between $220$ and $240$ volts. In areas without local substations, pole-mounted transformers perform this voltage reduction function.

Understanding electricity generation

Electricity represents the movement of electrons along conductive materials. Electrical energy is created through changes in potential, kinetic, or mechanical energy. The concept of electrons flowing in a circuit resembles water flowing through a pipe - the amount of energy flow per second is measured as current.

Summary