Energy and Electricity - Renewable Energy in Power Systems - page 1

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Energy and Electricity

1.1 The World Energy Scene
1.1.1 History
Energy demand in the pre-industrial world was provided mostly by man and animal power
and to a limited extent from the burning of wood for heating, cooking and smelting of metals.
The discovery of abundant coal, and the concurrent technological advances in its use, pro-
pelled the industrial revolution. Steam engines, mechanized production and improved trans-
portation, all fuelled directly by coal, rapidly followed. The inter-war years saw the rise of
oil exploration and use. Access to this critical fuel became a key issue during the Second
World War. Post-war industrial expansion and prosperity was increasingly driven by oil, as
was the massive growth in private car use. More recently a new phase of economic growth
has been underpinned to a great extent by natural gas.
A substantial proportion of coal and gas production is used to generate electricity, which
has been widely available now for over a century. Electricity is a premium form of energy
due to its fl exibility and ease of distribution. Demand worldwide is growing, driven by the
explosion in consumer electronics, the associated industrial activity and the widening of
access to consumers in the developing world.

1.1.2 World Energy Consumption
The present global yearly primary energy 1 consumption is, in round fi gures, about 500 EJ. 2
This is equivalent to about 1.4 x10 17 W h or 140 000 TW h . Dividing this fi gure by the number
of hours in the year gives 16 TW or 16 000 GW as the average rate of world primary power

1 Primary energy is the gross energy before its transformation into other more useful forms like electricity.
2 The unit of energy in the SI system is the joule, denoted by J. Multiples of joule are kJ, MJ, GJ, TJ (T for tera
denoting 10 12 ) and EJ (E for Exa denoting 10 18 ); the unit of power is the Watt (W) and represents the rate of work
in joules per second. Electrical energy is usually charged in watt-hours (W h) or kW h. Joules can be converted into
W h through division by 3600.