Chapter 15Energy from Organic Fuels

Fuel

● Fuel is any substance from which energy can be obtained.

● The law of conservation of energy states that energy cannot be created nor destroyed only transferred

Evolution of Energy

● Hunter gatherer societies used wood for their energy needs of only light, heat, and cooking.

● Modern industrial society uses forty six times more oil per person than other countries.

Evolution cont.

● Agricultural societies used domesticated animals for their energy needs.

● Then in the industrial revolution fuel was used for farming, building, manufacturing etc.

Organic Fuels

● Contain carbon compounds that were once a part of a living organism.

● Hydrocarbon – a compound composed only of carbon and hydrogen

Fossil Fuels

● Plants receive energy from the sun and animals receive energy from the plants. When buried the energy stays locked in their cells.

● Ex. coal, petroleum, and natural gas

Coal 15.2

● Millions of years ago our deserts used to be swamps. The plants accumulated and through heat and pressure all of most of the hydrogen and oxygen are lost. This forms solid rock called coal. The more carbon the more energy.

Peat

● Peat is not coal but the first stage of the formation of coal.

● It is brittle, brown plant material that contains a great deal of water and low carbon.

Lignite

● After the peat becomes deep the heat and the pressure force out all of the water.

● This forms a soft brown coal called lignite.

● Contains forty percent carbon and must be mined.

Bituminous coal

● This contains eighty five percent carbon and is the most abundant in the united states.

● Contains fewer impurities so it burns cleaner.

Anthracite Coal

● It has the least water, fewest impurities, most depth, and highest carbon percentage at ninety five percent.

● Burns the hottest and the cleanest.

Petroleum

● Coal is the the solid fossil fuel. The liquid fossil fuel is petroleum also called crude oil.

● Petroleum is thought to be formed from the remains of plankton.

Petroleum

● Crude oil becomes trapped under sediment and nonporous rock which builds up pressure and forms a geyser.

● Uses: gasoline, diesel, asphalt, and produce electricity.

Natural Gas

● The gas form of fossil fuels is natural gas that is made mostly of hydrocarbons and some other gases.

● Uses heating and running appliances such as the stove, water heater, and washer and dryers.

Natural gas

● Natural gas is usually found with petroleum.● It also burns the cleanest.

Organic Fuels 15.4

● Problems with fossil fuels Availability: Fossil fuels are non-renewable. All of

the fossil fuels that we use are already here. The more we search for oil the more we damage to

the environment we may cause. Desert storm should have shown America that we

need to reduce our dependency on foreign oil.

Problems cont.

● Pollution: fossil fuels produce a large amount of air pollution. Which some think is related to global warming.

● Oil spills can greatly damage habitats.● Coal miners can die from suffocation by natural

gas.

● So what are our options?

Biomass Fuels

● Fuel formed from the renewable products of living organisms. These can be generated specifically for the use of fuel. Wood – is still used in

many parts of the world as an energy source

● Negatives: it is highly concentrated in carbon and the harvesting of it can damage the forest.

Biomass cont.

● Garbage – two-thirds of all garbage can be burned. Some cities in the us produce electricity this way. We are also having a problem with to much garbage.

● Methane is produced from garbage dumps and swamps. Used in the same way as natural gas.

● Alcohol – the conversion of organic materials into fuels is called bioconversion.

● This can be made from corn or sugarcane.

● Known as ethanol which burns very clean and is renewable.

Chapter sixteen

Nuclear Energy

16.1 Atoms and Radioactivity

● All common forms of matter are made up of atoms.

● These are made up of protons, neutrons, and electrons.

• The cluster of protons and neutrons in the center of the atom is called the nucleus. It is orbited by electrons.

• The Atomic mass of the atom is weight of the nucleus. (the number of the protons and neutrons)

Isotopes

● The atomic number is the amount of the protons.

● Usually atoms of the same element have the same number of neutrons, when they do not they are known as isotopes.

Radioactivity

● Some isotopes of an atom are unstable. These isotopes decay emitting energy and particles form their nuclei.

● Marie Curie (Nobel prize winning chemist) named these atoms radioactive.

Radiation

● These are the three types of particles given off known as radiation

Alpha particles – contains two protons and two neutrons.

Beta particles – turn a neutron into a proton.

Gamma particle – electromagnetic radiation

Half-life

● The amount of time it takes for half the atoms in a sample of a radioactive element to decay is called the isotope’s half-life.

16.2 Reactions and Reactors

● Energy is required to hold the protons and neutrons in an atoms nucleus together.

● We can release this energy by splitting a large nuclei into smaller nuclei.

Nuclear Fission

● The energy produced by the splitting of these atoms is known as fission. This can be used to produce electricity.

● Uranium-235 is the most commonly used in nuclear reactions.

• It is split by a neutron striking the nucleus.

• When it is split other neutrons are sent out that strike other nucleuses causing a chain reaction.

Nuclear Reactors

● Three percent of nuclear fuel is from

U-235.

● The reaction takes place in a nuclear reactor vessel with dimensions 20m tall and 15m – 30m thick made of steel in side a thick concrete casing.

• The reactor has fuel rods positioned vertically in the center of the reactor.

• Water circulates between them to cool the reactor and slow the neutrons.

• Control rods made of cadmium and boron can control the rate of the chain reactions.

• The water may reach 275 degrees Celsius it then enters pipes to heat water which produces steam. That turns turbines.

Breeder Reactors● Ninety-seven percent

is U-238 which is non-fissionable. It can absorb a neutron and give rise to plutonium-239.

● The United States does not use breeder reactors because plutonium-239 can be used to make an atomic bomb.

16.3 Radioactive Waste

● Nuclear plants produce large amounts of waste.● Exposure to this waste can be very harmful to

living organisms.

Types of Waste

● Radioactive waste that emits large amounts of radiation are called high-level radiation. (Ex. Fuel rods, water in reactor)

● Medium and low level radiation – does not emit as much radiation but is generated in larger amounts. (found in uranium mines or hospitals)

Disposal

● It is very dangerous due to the long half-lives plutonium can last up to 192,000 years.

● One method of disposing waste it to put it in a leak proof container, under ground in a geologically safe environment.

• Most is not disposed of at all it is stored in tanks outside of plants. A number of these have began to leak. It would take an estimated 20 billion dollars to clean this up.

• There is no true method of permanent disposal plan for nuclear waste.

Meltdown

● A meltdown occurs when the nuclear chain reaction is not controlled and melts the reactor.

● A full meltdown releases a vast amount of radiation.