Harnessing the Sun

Harnessing the Sun

The sun is an extraordinary powerful form of energy. In fact, the Earth receives 20,000 times more energy from the sun than we currently use. If we used much more of this source of heat and light, it could supply all the power needed throughout the world. We can harness energy from the sun, called “solar energy”, in many ways. Satellites in space have large panels covered with solar cells that change sunlight directly into electrical power.

Some buildings have solar collectors that use solar energy to heat water. These panels are covered with glass and are painted black inside to absorb as much heat as possible. Some electric cars are even powered by solar panels. Solar energy is a clean fuel, but fossil fuels, such as oil or coal, release harmful substances into the air when they are burned. Fossil fuels will run out eventually, but solar energy will continue to reach the Earth long after the last coal has been mined and the last oil well has run dry.

Saving energy

An energy-efficient house is designed to minimize energy waste. It generates its own electricity, but it is still connected to the national power grid. If it generates more electricity than it needs, the excess is supplied to the grid. If it needs more electricity, this supplied by the grid.

Keeping warm

Most of the heat lost by a house escapes through the roof. The roof of an energy-efficient house is lined with insulation material to stop heat from escaping.

Solar panels

When the sun shines on a solar panel, solar energy is converted into electricity to power electrical appliances in the house, such as water heaters or cooling fans.

The Sunny Side

Many houses are built today with one long side facing the sun so that it can absorb as much solar energy as possible during the day.

Harnessing the Sun. Photo by Elena.

Small windows

Windows that do not face the sun are smaller, to reduce heat loss.

Water tanks

Hot water from the roof-top solar collectors is stored in tanks for later use. The tanks are insulated to stop the heat from escaping.

Cover Up

Awning shield windows from the excessive heat and glare of the sun.

Skylights

These let in natural light and can be opened to let war air escape.

Walls

The walls are filled with insulating materials to stop heat from escaping through them.

Large Windows

Windows facing the sun are large so that plenty of solar energy can pass through and warm the rooms inside. In the evening, when the sun sets, heavy curtains or shutters are closed over the windows to stop the heat from escaping.

Warming Up

Greenhouse are made of glass and have slanted roofs to allow the maximum amount of sunlight to enter. The sun's heat is trapped inside, which raises the temperature inside the greenhouse and helps the plants to grow. Plants in a greenhouse can be grown all year around.

Solar Cells

Solar cells convert light directly into electricity. Light reaches the cell through a transparent protective coating. The first layer is made from a material called N-type silicon (silicon is one of the most plentiful elements in the Earth's crust). N-type silicon is specially treated so that it has more electrons than normal silicon. This has gaps in its structure because it has less electrons. Sunlight gives electrons enough energy to jump from the N-type silicon to the P-type to fill the gaps. When electrons move, they make an electric current. The tiny currents made by hundreds of thousands of solar cells are added together to make an electric current that is large enough to power equipment.

Human, Bow Down

Human, Bow Down

By James Patterson and Emily Raymond, excerpt

Mikky stands tall, as proud as she can look in her dirty clothing. Heer commander holds out his gun – his very own – and she hubmly accepts it, bowing don in gratitude.

She has been forgiven.

She straightens and offers him a competent, merciless smile. “Sir,” she says briskly, “who shall I terminate first?”

A noise from the hall makes MosesKhan turn and look expectantly at the door.

A moment later, it bursts open, and a creature is dragged into the room. A spitting, hissing thing that seems like a cross between an adolescent girl and a jackal. It curses and flails, but the two Hu-Bot guards hold it steady, unperturbed by such feeble, animal attempts to escape.

“Get your fake-ass hands off of me, skin job,” it screams. “I”ll yank your circuits right out of your neck!” Then the figure looks up through its tangled hair and sees Mikky. It eyes widen in shock and relief. “Mikky!” it cries. “Helps me!”

Mikky goes rigid. She recognizes the human now: 68675409M, the Corvette thief. The one who caused her fall from grace. Her grip tightens on the gun.

MosesKhan steps forward, the hint of a smile playing about his lips. “You know what to do now, MikkyBo,” he says. He gestures toward the revolver in her hand. “Make it hurt,” he tells her, loud enough for the human to hear.

Mikky nods. Considers which extremity to hit first. Would the stomach hurt more than the knees, or would she die too quickly?” She palms the gun, feeling its heft. A .44 Magnum cartridge, she guesses: powerful enough to shred the girl like a grenade.

At such close range, Mikky's going to have to work hard not to kill the girl immediately. She licks her lips. Aims for a kneecap...

“Mikky, don't do it,” the girl says desperately. “This isn't you. They've done something to you.”

Mikky's focus doesn't waver. “Correct. They have repaired my problematic glitch,” she says tonelessly.

68675409M shakes her head. “No, Mikky, that's not true. Don't let them take control,” she says urgently, her sweaty desperation coming off her in pungent waves. “I know you. You're not a robot – you”re a person.”

Person? Mikky thinks, nearly chuckling as she cocks her weapon. With an insult that hateful, the human is clearly begging to die.

A spitting, hissing thing that seems lie a cross between an adolescent girl and a jackal. 

Barbie, Human, Bow Down. Photo by Elena.

Ancient World

The Black and the Red

An Ancient World

People began to live beside the River Nile many thousands of years ago. The river cut through the desert and provided them with water. The valley of Upper Egypt in the south formed a long narrow strip; the delta of Lower Egypt in the north spread out across the river mouth. Every year, floods washed thick mud over the banks and lef good soil behind. Early Egyptians called this the “Black Land” and used it for growing crops. Beyond it was the “Red Land,” an immense stony waste where it hardly ever rained and nothing useful grew. Where the Black Land ended, the Red Land began. A person could stand with one foot on fertile ground and the other on dry sand. Wolves and jackals hunted along the edges of the desert, but human enemies were seldom able to cross it and attack ancient Egypt.

The Cliffs of Thebes

Limestone cliffs line the western boundary of the valley of Thebes. Pharaohs built temples on the edge of the floodplain and tombs in the hills beyond.

Alexander's Alexandria

Alexander the Great invaded Egypt in 331 BC, and planned a great city called Alexandria.

The Monuments of Giza

The pyramids and the sphinx at Giza are landmarks of ancient Egypt, visible from a great distance across the desert.

Ancient World. Photo by Elena.

Queen Hatshepsut's temple

Queen Hatshepsut, who ruled as pharaoh, built a terraced temple at Deir el-Bahri on the west bank of the Nile. She filled the gardens with sweet-smelling plants.

Abu Simbel

Ramesses II ordered two huge temples to be built in the desert at Abu Simbel in Nubia. They were carved out of the sandstone cliffs.

Temples at Karnak

Karnak was an important religious center. Stone columns with elaborately carved tops supported the heavy roofs of the huge temples.

Marsh Hunt

The hunter felled birds with his throwing stick after his trained cat had startled them from the papyrus reeds.

Land of the Lotus

People in modern times likened ancient Egypt to a lotus plant, with its valley as the stem and its delta as the flower.

The Civilization of Ancient Egypt

Old Stone Age: Before 12,000 BC. The earliest Egyptians hunted lions, goats and wild cattle on land, and hippopotamuses and crocodiles in the river marshes.

New stone Age: Begins about 4500 BC, during this period, people discovered fire for cooking. They learned to herd animals and to grow grain. New stone-age pottery witness that.

Land of two kingdoms: Begins about 3000 BC. Ditches were dug to irrigate the land and villages became more established. In 3100 BC, Narmer united Upper and Lower Egypt. Narmer”s palette shows his victory.

Rule of the Pharaohs: 2920 BC to 322 BC. Egypt was strong for much of this time. Monuments were built and trade with foreign countries developed.

New Design

A New Design in the Industrial World

After the Second World War, many nations around the world made great economic recoveries. People felt confident and full of adventure. Architects of the 1950s and 1960s designed buildings with unusual shapes to reflect this new confidence. Some buildings have simple geometric shapes, while others look like huge abstract sculptures. 

Many of these structures could not have been built without the invention of a new material called reinforced concrete. A roof of reinforced concrete will bridge a wide room without any other supports in between. Steel and reinforced concrete are so flexible that walls and ceilings can be built into any shape. Sometimes the walls of a room or ceiling were built so they curved away from the people inside the building. This was done to give people a feeling of exhilaration – the spirit of the time in which these buildings were designed and constructed.

A Better Building Material

Reinforced concrete is made by pouring concrete into molds around steel rods or wire mesh. The kind of concrete is no longer brittle, so roof supports can be set farther apart. Concrete reinforced with wire mesh is used to build thin, lightweight ceilings and walls and can be easily molded into any shape desired. The bowl shape of the assembly room in the Palace of the National Congress in Brasilia, Brazil, is possible because of reinforced concrete.

Manhattan modern buildings. Photo by Elena.

The construction of an innovative building is difficult and often requires new techniques and special building materials. Many unexpected problems arise no matter how careful the advance planning may be. The architects and engineers building the Opera House in Sydney, Australia, faced major obstacles. The design was so innovative that it took several years for engineers to work out a way to actually build it.

Specialists in sound, called acoustical engineers advised on how the chosen building materials would affect the quality of sound. Metal, plastic and glass from around the world was used in the building. Manufacturer designed essential new equipment and construction workers learned new skills to build the Opera House. There were many unexpected costs and delays in construction. The architect's imaginative design became a unique masterpiece, which today is recognized throughout the world.

A Global View

A great building can reflect many different ideas and styles and tells us about the beliefs and values of the people who designed and built it. Ancient buildings around the world looked different because they were shaped by the building materials available. Each material inspired a different construction method People in the forest areas of Europe built in wood. Wood was scarce but stone was plentiful along the Mediterranean coast.

Passing on the Power

Passing on the Power

Electricity has to be sent from the power station where it is made to the homes and businesses where it is used. Whether the power station is nuclear powered hydroelectric or burns coal, the electricity it makes is distributed in the same way. Transformers at the power station boost the electricity to a very high voltage-hundreds of thousands of volts. The electricity is then carried by metal cables suspended from tall transmission towers, or pylons. It usually ends its journey by passing along underground cables. By the time it reaches your home, transformers have reduced its voltage to a level that depends on which country you live in. Electricity generated in one place can be sent to another part of the country if more power is needed.

Turbogenerator

Electricity is made by a turbogenerator – a generator driven by a turbine. When a wire moves near a magnet, electricity flows along the wire. Inside the generator, strong magnets make electricity flow through coils of wire.

Rotor

The rotor consists of coils of wire that rotate at high speed. Electric current flowing through the coils creates powerful magnetic fields around them.

Anode

A carbon rod acts as the positive electrode.

Passing on the power. Photo by Elena.

Electrolyte

This is a chemical paste.

Cathode

The zinc battery case forms the negative electrode.

Batteries

When a battery is connected to an electric circuit, a chemical reaction between the negative terminal (cathode) and a liquid or paste (electrolyte) creates a current. This current travels round the circuit and returns to the battery at the positive electrode (anode).

Rotor

The rotor consists of coils of wire that rotate at high speed. Electric current flowing through the coils creats powerful magnetic fields around them.

Transformers

Transformers increase the voltage before electricity is transmitted.

Electricity Distribution

Electricity generated at a power station is distributed through a network of cables above and below the ground.

A Bright Idea

Most light bulbs contain a thin coiled wire filament that heats up and glows when an electric current flows trough it. They are called incandescent bulbs. An energy efficient bulb is a fluorescent tube that needs less electricity to produce the same amount of light as a normal bulb. When an electric current passes through mercury vapor inside the tube, the vapor releases invisible ultraviolet rays, and the coating on the inside of the bulb converts them into visible light.

Stator

The stator which does not move, is made from coils of wire surrounding the rotor. As the rotor turns, its magnetic fields cut through the stator coils and make an electric current flow through them.

Power take-off cables

Thick cables lead electric current away from the generator.

Transmission towers

The transmission lines are held high above the ground by tall transmission towers. Glass or ceramic insulators between the metal towers and the cables stop the current from running down the towers into the ground.

Transmission line

Cables strengthened by steel carry the current.

Street transformers

Before electricity reaches your home, its voltage is reduced by transformers. The voltage level depends on the country you live in.

Home

Electricity enters your home through a meter that measures how much electricity is used.

Did you know?

Power stations have to be ready to boost electricity production whenever demand suddenly increases. In many countries, television schedules help to predict power demands. At the end of films or major sporting events, the demand for electricity soars as millions of television viewers switch on their electric kettles to make tea or coffee.