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The Sun as an Energy Source An Introduction to the Science Behind Solar Energy Kevin Young

The Sun A star that is very close To Earth

This is not a new concept… The sun’s energy has been used for centuries to:  Dry clothes  Dry meats  Plants use solar energy to make food through a process called “photosynthesis”  Therefore, fossil fuels are solar energy stored for billions of years

Journey to the center of the Sun 1. Corona 2. Chromosphere 3. Photosphere 4. Convective Envelope 5. Radiative Envelope 6. Core

The Birth of Solar Energy: The Core  Solar energy is “made” in the core  T = 15.6 million degrees Celsius  156,000 times boiling water  P = 250 million atmospheres  250 million times the pressure at Earth’s surface  It is a product of nuclear fusion  The energy travels through the sun’s layers, solar system, and eventually reaches Earth

Nuclear Fusion  A special chemical reaction  Simply, when two atomic nucleii are joined to form a larger nucleus,  Energy is given off or absorbed  Hydrogen is fused to form Helium in the sun

Atoms!  Everything is made up of atoms  Your desk  Your body  Air  Water  They are the building block of the universe.  Different substances are made of different atoms. These are called chemicals.

Examples of atoms  Hydrogen (part of water)  Oxygen (what we breathe and the other part of water)  Helium (what makes balloons float)  Sulfur (what makes some water stink)  Sodium and Chloride (these two make up table salt)

Atomic Structure Simple Bohr Atomic Model + Nucleus Made up of non- charged particles called NEUTRONS and positively charged particles called PROTONS Electrons ELECTRONS are negatively charged particles that orbit the nucleus at a certain distance - - -

Atomic Structure: Hydrogen (H)  Hydrogen contains one proton and one electron + -  Helium contains two protons, two neutrons, and two electrons

What is a chemical reaction?  When two or more substances called chemicals come together and change into one or more different substances.  Think of Legos  When separate, Legos are just bricks, but together they can form houses, spaceships, even people! This is the same with chemicals.

Solar Nuclear Fusion!!!  Four Hydrogen atoms are put together to form one Helium atom.  The atoms are happier as Helium so they give off a sigh of relief in the form of energy  This energy is called a gamma ray.

The chemical reaction Gamma Ray (ENERGY!)

I thought solar energy was in the form of light?  Correct!  Gamma rays travel from the core through about 80% of the sun  It becomes harder and harder for the rays to get out of the sun so they lose energy.  When they lose energy they form photons (visible light)  They are emitted and reach Earth as photons

The Sun: An Energy Machine!  This reaction takes 1,000,000,000 years to complete!  386 billion billion megawatts  A power station for a city makes about 1,000 megawatts  700 million tons of Hydrogen are converted to 695 million tons of Helium every second That means 5 million tons of energy are produced every second!!! Think about how much visible light it would take to make 5 million tons!!!!!!

Solar Energy on Earth  About 30% of the sun’s energy is blocked before it reaches earth  Shielded by:  Atmosphere  Clouds

Energy Path

Photosynthesis Electricity Heat atmosphere

Photosynthesis Energy in the form of food

How is this energy used?

The Energy Pyramid Energy Primary Producers (Photosynthesis ) Primary Consumers Secondary Consumers Tertiary Consumers

Energy Transfer A Joule is a way to describe energy. It is named after this guy James Prescott Joule It takes 4.2 Joules to heat 1 gram of water 1 degree Celsius. If 1,000,000 Joules of sunlight hit a field of grass, how is this energy Transferred to the ecosystem? / 100 / 10 / 100 / 10 / 100 / 10 / 100 / 10

Oil: Fossil Fuels  Fossil Fuels are made of thousands of years old dead plants and animals  They are buried under tons of Earth and the energy contained in the plants and animals is converted to oil.  Oil is then used to make gas for cars and other engines, including ones that create electricity!!!

Solar Panels  Are used to “collect” solar energy  Convert solar energy to electrical energy that can power household items, such as lamps or calculators  To understand how they work we must first understand what electricity is…

What is electricity?  Remember the structure of an atom?  Electricity is simply the flow of electrons!

Electricity This happens millions of times to produce enough electricity to power Our homes.

Photovoltaic Cells This happens millions of Times to produce electricity

Solar Oven Cup 1. Cut cup in half 2. Line inside bottom with black paper 3. Wrap piece of black construction paper with aluminum foil shiny side up 4. Make the foil into a cone insde top of cup 5. Place bottom inside the cone and tighten.