89 Water Power The Greatest Force on Earth

CHAPTER 1 Water on Earth IT IS NO SURPRISE WE CALL THE EARTH "THE BLUE PLANET." AFTER ALL, OVER 60 PERCENT OF ITS SURFACE IS COVERED WITH WATER. It is water that gives Earth its beautiful blue color that we see in photographs taken from space. No other planet that we know of in the universe has so much water, that amazing element so essential to life. Water goes through a cycle that never ends. It falls from the sky as rain and snow, sleet, and hail. On high mountains, glaciers melt and water flows from narrow streams and wide rivers into lakes and eventually into the seas and oceans. Then, through a process called evaporation, water rises from the seas to the skies where it turns into clouds. And the cycle begins again. Water can be liquid, solid, or gas; it can be gentle or rough; it can bring life or death.

Water has power over us maybe more than anything else on the planet! Without water, no human, animal, or plant could survive. Humans have long used water for washing, growing food, and raising animals. Water has also been used as a means of transportation, as a source of recreation, and as a household tool. Now, we also use water as an industrial tool and as a source of energy. But too much water can be a bad and dangerous thing. Think of floods, for example. Fast-moving, deep water can drown people; it can sweep away vehicles and even buildings. Also, floodwater may contain bacteria that cause diseases and that can affect our drinking water. Water gives us power, but it also has power over us.

CHAPTER 2 Water in Industry THE AMOUNT OF WATER USED IN INDUSTRY IS GROWING STEADILY EACH YEAR. AS MORE COUNTRIES DEVELOP ECONOMICALLY, MORE WATER WILL BE NEEDED FOR INDUSTRIAL USE. Water is important in industry. In fact, about 20 percent of all the water we use around the world is for industrial purposes. We need water in every step of the industrial process. For example, sometimes water is needed in the production of food items like soft drinks, soups, and juices. And we also need it for things like soap, shampoo, paint, and cleaning liquids. But did you know that water is required for the production of plastic and glass? Water is even used when making cars! It takes about 2,000 liters of water to make one car tire! It sounds unbelievable, but it's true.

We need tools to make things, and water can also be used as a tool. For example, water is often used to cut things. When a line or jet of water is shot out at a high speed and under high pressure, it can be very strong— strong enough to cut through glass, metal, and stone. Because of this, water jet cutting machines are used in industries like mining and aerospace to cut things to the right shape. Water jets are also used at the dentist's office to help us keep our teeth clean. Fortunately, they're not as strong as the ones used to cut stone or metal! Water is also used in industry as a lubricant something that can help prevent machines from wearing out when their parts move against each other. Right now, most industrial lubricants are made with oil, but because using oil in this way is not good for the environment, inventors are developing water-based lubricants. Because water is inexpensive and easy to get, it is also used as a coolant— to cool down the moving parts of machines in factories and power plants.

Water is also used to move things where they need to go. Trees are cut down and floated along rivers from faraway forests, for example. It would be hard, in fact, for trade to exist without water as a means of transportation. Shipping is a huge industry that helps us move the things we make around the world as cheaply as possible. And water is also used to transport waste— including human waste! —to waste-treatment facilities, where it is diluted, broken down, and dealt with safely.

Water is also used to create the power we need to keep our industries running. Hydroelectric generating plants use the energy of falling water to turn turbines, which then create electricity. This electricity is taken to cities and towns along power lines. Without water, most industrial work would be more dangerous, more expensive, and, in some cases, impossible. But there are problems. For example, industrial processes may cause pollution. Dangerous chemicals can pollute the water, harm people, and damage the environment.