CHAPTER TWO
The Science of Energy
What is energy? Energy is the most fundamental physical thing in the universe. Without it, nothing is! It is a scientific quantity with a unit. The standard unit for energy is the joule. But most people seem to prefer the calorie. Scientists measure energy in joules. Just how large is one joule of energy? Well, try raising a brick from the ground to your waist. If it is a standard brick and you are an average person, you have just done about 20 joules of work. In other words, you have just used up about 20 joules of the energy that was being stored in your tissues. Now, 1 calorie = 4.2 joules. So the earlier figure in calories is 4.8. If you are a 60 kilogramme person and you climb up a standard flight of stairs, you would have used up about 1800 joules or 430 calories. Leave a 60-watt bulb burning for 1 hour and you would have used 216000 joules of energy. There is a simpler way of saying this: 216 kilojoules, since 1 kilojoule is 1000 joules. Your instant shower heater is an energy guzzler. If it is rated at 2500 watts and is kept running for 5 minutes, you would have used nearly ž million joules of energy just for a shower!
Units Used in the Energy Industry Clearly, the joule is a small unit of energy. It takes about a joule of energy to stretch out your arm vertically. Given the way in which the average person uses energy, we would have to use very large numbers to represent ordinary consumption figures in joules. Here, the physicist comes to the rescue. Enter the kilowatt-hour (kWh). 1 kWh is 3.6 million joules. Electricity supply companies such as TNB use the kWh as the basis for calculating your energy bill. TNB refers to this as one unit of electrical-energy consumption. At minimum rates, you would owe TNB 21.8 sen for using one unit of electrical energy. Air-conditioners are the big users of electricity in the energy scene. For example, a 1½ horsepower medium-sized split unit, in scientific terms, has a power of 1.1 kilowatts. If left on for 6 hours, 6.6 kilowatt-hours of power would have been used. This is equivalent to 6.6 units, costing RM1.44 (at the current tariff rates). The oil industry uses a unit called a barrel as a measure of quantity. One barrel of oil has a volume of 42 US gallons or 160 litres. The energy worth of this barrel of oil is 9