Electric City

Programme Outline

This programme is based around Las Vegas – a consumer of electricity – and the Hoover Dam as its main provider. We are given a brief history of the city and the dam with some stunning overhead shots. The programme explains how electricity is generated inside the dam and transmitted across the desert, and why transformers are used to change the voltages. Finally, we look at the environmental advantages of neon lighting and of hydroelectric power.

00.00 - 03.30 Introductory flight over Las Vegas – a huge consumer of electricity – and the Hoover Dam
Uses of electricity. Introduction to hydroelectric power generation.

03.30 - 05.37 The anatomy of the Hoover Dam and its generators
Electricity is generated from the pressure of falling water. The turbines convert this into rotational motion and the generators then produce the electricity.

05.37 - 06.37 Model of an AC generator
A moving magnet can induce a voltage in a coil. A spinning magnet will induce an alternating voltage.

06.37 - 08.21 The Hoover Dam's generators and their power. Transformers and power lines
The dam has a total of 17 generators. One generator produces a power of 100 MW: enough to light a million 100 W light bulbs. Transformers step the voltage up from 16,500 V to 230,000 V AC.

08.21 - 08.53 Coal-, gas- and oil-fired power stations
Other ways of turning a turbine to generate electricity.

08.53 - 09.16 Stepping down the voltage at the substation
The very high transmission voltage would be dangerous around the town, so the voltage is stepped down from 230,000 V to 12,500 V.

09.16 - 11.00 The Luxor Hotel and hotel transformers
A large hotel has its own transformers which step down the voltage: to 4,160 V for air conditioning, and to 120 V for lighting and so on.

11.00 - 11.37 Local transformers
The substation voltage is stepped down to 110 V AC for use in homes.

11.37 - 13.20 Why the voltage is changed. Why AC is not transmitted at a low voltage. Infra-red images of wires carrying power at high and low voltages

The electricity is generated at 16,500 V and stepped up to 230,000 V for transmission. It is stepped down to 12,500 V in a substation, and finally to 110 V for consumers. The reason for transmitting at a high voltage is that it is more energy-efficient to do so.

13.20 - 15.00 Lighting Las Vegas efficiently. Neon lights. Infra-red image of filament and neon bulbs
Neon lights and fluorescent lamps are more efficient than filament bulbs. The amount of light from a 5 W neon bulb is the same as that from a 15 W filament bulb. Filament bulbs waste energy because they become hot.

15.00 - 17.16 Making neon lights and getting different colours from different gases
The operation and construction of a discharge tube. Different gases give different colours: argon - purple; neon - red; helium - pale blue; krypton - silvery white; xenon - deep blue.

17.16 - end Summary of key points. Environmental impact of the Hoover Dam
The Hoover Dam is a pollution-free and a renewable energy source. No fossil fuels - which produce carbon dioxide (CO2) and are not replaceable - are burnt in the generation of hydroelectric power.