Presentation on theme: "Fossil Fuels. What is a Fossil Fuel? ●Burn to change chemical structure and release energy ●Coal ○ plants hardened by sand and mud (photosynthesis energy)"— Presentation transcript:
What is a Fossil Fuel? ●Burn to change chemical structure and release energy ●Coal ○ plants hardened by sand and mud (photosynthesis energy) ○ Must be dug up (expensive and difficult) ○ rate used greater than rate of production (non renewable)
What is a Fossil Fuel? ●Oil and Gas ○ microscopic organisms hardened over time ○ easier to extract (liquid form) ○ non renewable
Geography ●Easy to find (as of 4000 years ago) ●Must use coal near source (hard to transport) ○ eg: trains must carry coal ●OIl is easily pumped - can be transported (pipes) ●Drill technology allows drilling across world
History ●Originally wood used - more suited to needs ●Coal accessible 1769 (Industrial Revolution) ○ Coal has twice the energy density of wood ●Crude oil refined to kerosine (1852) ○ oil has higher energy density than coal ●As of years of coal left (1E15kg) ●As of about 1E14 liters of crude oil left
Transportation and Storage ●Coal ○ Required a lot of time and energy to transport ○ Combustion risks ○ More efficient to produce electricity ●Oil and Natural Gas ○ Can be pumped through pipes ○ Transportation Environmental problems ○ Stored indefinitely
Energy Density Energy Density( of Fuels) : The ratio of the energy released from the fuel to the mass of the fuel consumed ●The amount of energy that can be extracted per kg of fuel. ●Fuels with high energy density are easier to transport than those with lower densities.
Energy Density Chart
Power Stations A Power Station: An industrial place for the generation of electric power. Has a generator, a rotating machine that converts mechanical power into electrical power by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely. It depends chiefly on which fuels are easily available, cheap enough and on the types of technology that the power company has access to.
Coal-fired Power Stations ●Coal Steam ●Steam Electricity ●Steam Water
Coal-fired Power Stations ●Sources of waste heat: ○ exhaust gas ○ turbine condensing ○ friction ●40% Efficiency
Oil-fired Power Stations ●Same set-up as Coal-fired Power Stations ➢ Oil is burnt to produce energy needed to boil the water ➢ Cleaner, easier to get out of the ground, and easier to transport than coal ●Efficiency is about 59%
Gas-fired Power Station ●More Efficient than coal ➢ Two stages of energy use ➢ Burning gas goes through a turbine => heat produced is used to boil water => steam powers a steam turbine
Gas-fired Power Stations ●Up to 59% efficient ●If wasted heat goes to homes => 80% efficient
Environmental Repercussions Coal-fired and Gas-fired Power Stations= harmful pollution from exhaust Oil refinement=efficiency… but also= oil spills ➢ Serious consequences (i.e. BP Oil Spill) Power Station developments focus on recovering exhaust (by different trapping techniques) back into the ground for reuse
Practice Problem #1 When a car is driving at 80 km/h it is doing work against air resistance at a rate of 40kW a) How much work does the car do against air resistance in 1 hour? 40E3(J/s) * 60 * 60 = 1.44 E8 J b) If the engine is 75% efficient, how much energy must the car get from fuel?
Problem 1 (cont) 1.44E8 J/.75 = 1.92E8 J c) If the energy density of the fuel is 45.8 MJ/kg, how many kg of diesel will the car use? 1.92E8 J/45.8E6 J/kg = 4.2kg
Practice Problem #2 A coal-fired power station gives out 1000 MW of power a) How many joules will be produced in one day? 1000E6 J * 60 * 60 * 24 = 8.64E13 b) If the efficiency is 40%, how much energy goes in?
Problem 2 (cont) 8.64E13 J/.4 = 2.16E14 J c) The energy density of coal is 32.5 MJ/kg. How many kg are used? 2.16E14 J/32.5E6 J/kg = 6.65E6kg d) How many rail trucks containing 100 tons each are delivered per day? 1 ton = 1000 kg
Problem 2 (cont) 6.65E6/(1000*100) = rail trucks
Nuclear Power Austyn Howard Ciara Jasinski Dillon Labban Tyler Ritter
The Fission Reaction Big nucleus splits into two smaller nuclei o Loss of mass and energy, E=mc 2 i.e. 236 U → 92 Kr Ba + 2n Some neutrons are lost, so mass is lost The total number of protons remains the same
The Chain Reaction Splitting a nucleus requires energy o Can be gained by adding a neutron Adding a neutron increases the binding energy of the nucleus o Nucleus can’t get rid of this energy and splits in two o Results in too many neutrons, so some are released Released neutrons are captured by other nuclei, resulting in more nuclei splitting and a chain reaction
Moderation of Neutrons Chain reaction only occurs if neutrons are moving slowly o Otherwise they pass through the nucleus o KE should be about 1 eV Neutrons must be slowed down o Moderator nuclei are placed between nuclei where fission must occur in order to slow them down
Critical Mass Definition: the minimum mass required for a chain reaction o Size of the reacting element, i.e. uranium, matters If it’s too small, the neutrons will pass the uranium before they slow down enough
Nuclear Fuel Natural Uranium is mostly made up of 238-U (99.3%) and 235-U (0.7%). Before it can be used as nuclear fuel it needs to go through fuel enrichment. o in nuclear reactors the fuel is stored inside small cylinders that are stacked together to make rods Depleted uranium is used to penetrate armored vehicles, is 40% less radioactive than typical uranium When U-235 is used up it makes Pu-239 that goes through fission and can then be used for energy production or bombs
Controlling the rate of reaction The loss of control: The atom bomb If more than one neutron from each fission goes on to make another fission then the reaction will accelerate; if less than one then it will slow down In order to keep the bomb from exploding before hitting the ground the uranium and moderator are kept separate from each other Weapon grade amount of Uranium and isotope: o 85% 235-U is considered ‘weapon grade’ (about the same amount as a soft drink can would work) o 20% isotope is possible to make a bomb The only way to slow down the reaction is to introduce neutron absorbing rods (such as Boron) in between the fuel rods
The Nuclear Power Station It’s mechanism is similar to that of a furnace in a steam generator nuclear reactor
The Nuclear Power Station nuclear reactor: an apparatus or structure in which fissile material can be made to undergo a controlled, self-sustaining nuclear reaction with the consequent release of energy (heat). 3 crucial components: ●fuel elements ●moderator ●cooling rods
The Nuclear Power Station fuel elements heavy fissile elements o 235 U or 238 U when these fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart. chain reaction
The Nuclear Power Station Moderator slows down neutrons heavy water (deuterium)
The Nuclear Power Station control rods control the rate of fission reactions absorb neutrons Boron or Cadmium
Problems with Nuclear Energy getting the uranium o you can mine it, but… open-cast mining hurts the environment underground mining can hurt the workers o you can use “leaching,” but… this can lead to contamination of groundwater
an open pit uranium mine in Namibia
Problems with Nuclear Energy Steps to Achieve a Meltdown 1. do a bad job of controlling a nuclear reaction 2. allow fuel rods to melt 3. let the pressure vessel burst 4. release radioactive material into the atmosphere
Problems with Nuclear Energy meltdowns can be caused by: o a malfunction in the cooling system o a leak in the pressure vessel the reactor would be severely damaged, but external damage is limited by the containment building o protects the outside from dangerous material, protects the inside from missiles Tyler
revisiting the diagram, but examining different components
Waste low level waste o traces of radioactive material that need to be carefully disposed of kept away from humans for years o old reactors left alone for many years before demolition encased in concrete
Waste high level waste (spent fuel rods) o plutonium isn’t safe for at least 240,000 years o suggestions: send it to the Sun put it at the bottom of the ocean bury it in the icecaps drop it into a very deep hole o current plan: store it underwater at the site of the reactor for several years, then seal in steel cylinders
Waste weaponizing fuel o not enough 235 U to be used o process that enriches uranium into fuel, could be used to make it weapons grade o plutonium is most commonly used, can get it by reprocessing spent fuel rods
Benefits of Fission Doesn’t produce CO 2 or other greenhouse gases Fission results in increased sustainability o Plutonium can be created through the fission process, resulting in 2000 years of fuel o Naturally found uranium is estimated to only last 100 years
Fusion was thought of as the answer to energy problems in the 1950s the total mass of the larger nuclei is less than that of the smaller two combined, the extra mass is turned into energy fusion reactors have come close to creating more energy than what was put in but is still not enough to commercially produce energy Plasma (a gas in which nuclei and electrons are separate) is used to create energy in the system magnetic fields are used to move the particles through the system
Burning Plasma and Fusion Bombs the problem with creating fusion through energy is that every time more plasma is added the temperature has to be significantly increased in order for the nuclei to fuse the fusion bomb (hydrogen bomb) gives out a huge amount of energy but is not controllable
The Sun gravity pulls all of the mass inward → creates super duper high pressure (100,000,000,000 atm) hydrogen atoms fuse together → nuclear fusion 15 million degrees Fahrenheit at the core
Wave Power Catrina Letterman Joseph Leung Cyam Cajegas
The movement of air disturbs the water, causing waves As waves spread out, they spread their energy, which can be used to turn turbines Origin of waves
Device built on land that uses the kinetic energy of waves to force [compress] air in and out of a turbine which generates electrical energy Oscillating Water Column (OWC) Ocean-Wave Energy Converter
Generating Electricity from Waves
A 1.No Greenhouse Gas Emissions 2.Renewable Form of Energy 3.Enormous Energy Potential (30 to 100 kW per meter) 4.Reliable (Most in the winter season) 5.Area Efficient (half square mile -> 30MW) 6.Offshore Wave Power Advantages/Disadvantages D 1. Environmental Effects (sea life and tourism) 2. Expensive 3. Regular Maintenance 4. Still Developing
Calculating Energy in a wave
Calculating Power in a wave
Waves of amplitude of 1 metre roll onto a beach at a rate of one every 12 seconds. If the wavelength of the waves is 120 metres, calculate: a. the velocity of the waves b. how much power there is per metre along the shore c. the power along a 2km length of beach Practice Problems
a. v = m/s 120 meters/12 seconds = 10 m/s b. Given that power = pvgA^2/2, (1kg/m^3 * 10 m/s * 9.8 m/s^2 * 1^2 m^2) 2 = 49 kW c. 49 kW * 2000 m = 98 MW
Origin of tides Tides due to gravitational change of moon Movement of tides can be used to drive turbines
Turbines are turned as tide comes in and goes out
A 1.No Greenhouse Gas Emissions 2.Renewable Form of Energy 3.Predict Tides 4.Maintenance Cheap 5.Long Lifespan 6.High Energy Density Advantages/Disadvantages D 1. Environmental Effects (sea life and tourism) 2. Expensive 3. Few Viable Locations 4. Still Developing 5. Unpredictable Tidal Energy 6. Short Duration of Power Generation 7. Energy Transmission expensive and difficult
TEST TEST TEST
From what energy source are waves directly derived from? a. The Sun b. Wind c. Geothermal d.The Moon 1.
What is NOT required to determine the power of a wave? a. Density b. Wavelength c. Amplitude d. Temperature of water 2.
The tides are mainly caused by… a. The Sun b. The earth’s rotation c. The Moon d. The wind 3.
How much power (approximately) can a pelamis generate a. 150 horsepower b. 150 kJ/s c. 750 kW d. 750 kJ 4.
An oscillating water column generates power by… a. Air compression b. Tidal Change c. Wave’s Momentum d. Magnetic A/C Generator Buoy 5.
Waves off the 1.5km Leung Coast are used to generate power. A wave is modeled below Free Response Question
a. Determine the wave velocity. b. Determine the mass of 1 wave approaching the coastline. The Density of Seawater is 1027 kg/m^3 c. Calculate the potential energy of one wave. d. Calculate the power of one wave. Free Response Question
e. BONUS: What should the wave velocity be in order to power the 30000kW mega- awesome laserlight show in Joseph’s Coastal Mansion? Free Response Question
Ray Win KC Sumner Seanna Morin Jakob Hernandez Wind Energy
Wind Solar energy Sun heats earth, creates wind Solar Energy Kinetic Energy of Wind Kinetic Energy of Turbine Electrical Energy
Coastal Winds Due to different rates of heating of the land and sea Sea has a larger specific heat capacity than the land Example: Wind at beaches
Katabatic Winds Formed when high air pressure is caused by dense cold air pressing down at the top of a mountain Air flows downhill Examples: When cold air from Alps and Massif flow down towards Mediterranean coast
The Wind Turbine Similar to a fan or a propeller on an airplane Air pushes the fan blades causing a generator to turn, creating electrical energy Usually turbines grouped together in “wind farms”
The Wind Turbine
Formula assumes wind stops moving after it passes turbine All kinetic energy is not transferred to the turbine Theoretically, maximum percentage of wind’s energy that can be extracted using a turbine is 59% Also finds power due to the calculation using mass of air that passes through in one second
Places for Wind Turbines A windy place Regular wind Turbine doesn’t have to change orientation Easy to lay power lines Easy to build
Advantages Clean production No harmful chemicals Renewable energy source Free energy source After initial cost
Disadvantages Wind is unreliable Low energy density Large area required for significant energy Ruins country landscape Can be noisy Best places often far from population centers
Sample Problems A community wants to build a wind farm to fit its needs. Total required annual energy output: 100 TJ Space for 20 wind turbines Average annual wind speed: 9 ms -2 Deduce the average power output required for one turbine Estimate the blade radius that will give a power output found in part a (Density of Air = 1.2kgm -3 )
Solar Power By Ceres, Jace, Michael, and Terry
Energy from the Sun The sun emits 3.9E26 J per second of electromagnetic radiation This energy spreads out by the inverse square law since the energy is distributed in a sphere
Inverse Square Law Intensity can be found by the formula I=P/(4 π r 2 ) I=Intensity (power per unit area) P= total power of point source r= distance away from the point source
Solar Power intensity on earth Power per meter squared of solar energy above the Earth’s atmosphere: (solar constant) Earth’s orbital radius: 1.5E11 m Intensity = 3.90E26 / (4π X 1.5E11) 2 = 1380 W · m -2
Solar Power on Earth’s Surface Amount of solar radiation that reaches the Earth surface depends on how much atmosphere the light has to get through Different latitudes on the Earth’s surface will receive different amounts of radiation Will also vary with the seasons
NorthNorth More Less Atmosphere Travel Distance
Solar Heating Panel Panel uses heat from sun to heat water for household use. o Sunlight goes through glass panel and is absorbed by black metal plate. o Hot metal plate then heats water for use.
Solar Heating Panel
Solar Example A 5 m 2 solar heating panel is in a place where the sun’s intensity is 800 Wm -2. What is the power incident on the panel? 800 Wm -2 * 5 m 2 = 4000 W
Solar Example If it is 40% efficient, how much energy is absorbed per second? 4000 W *.4 = 1600 W If 1 kg of water flows through the system in 1 minute, how much will its temperature increase?
Solar Example If 1 kg of water flows through the system in 1 minute, how much will its temperature increase? (Specific heat capacity of water 4200 Jkg -1 K -1 ) q = mcT T = q/(mc) 1600 W*(60 s/1 min)/(1 kg*4200 Jkg -1 C -1 ) = 22.9 K
Photovoltaic Cell Converts solar radiation into electrical energy Semiconductors release electrons when photons of lights are absorbed Different types of semiconductors create an electric field
Photovoltaic Cell Only produce a small amount of p.d. and current o Using in series will get higher voltages o Using in parallel can provide higher current
Photovoltaic Example A photovoltaic cell of 1 cm 2 is placed in a position where the intensity of the sun is 1000 Wm -2. If it is 15% efficient, what is the power absorbed? 1 cm 2 =.0001m Wm -2 *.0001 m 2 =.1W
Photovoltaic Example.1 W *.15 =.015 W If the potential difference across the cell is 0.5 V, how much current is produced? P = IV I = P/V W/0.5 V =.03 A
Advantages vs. Disadvantages Advantages No harmful chemical by-products Renewable Free energy source Disadvantages Only utilized during the day Unreliable (cloudy days) Large area needed for significant amount of energy
Energy, Power, and Climate Change: Hydropower Michele Wang Tori Barr Diego Martinez Jacobo Grimaldo
What is hydroelectric power? The production of electricity through the conversion of gravitational potential energy from falling or flowing water.
Originally from the sun: Heat from the sun turns the water into vapor, which turns into clouds, which go over the land and rain over the land. Rain water on high ground has PE, and can be converted into electricity through rivers and lakes. Origin
PE=mgh ●h is the difference between the outlet from the lake and the turbine. ●Average height is used where the height is uneven. Gravitational PE
Turn off hydroelectric power at night. Excess power from coal-fired power stations can be used to pump water into a reservoir. (costly to turn off and back on) Water from reservoir can drive turbines during night. Reduces amount of fossil fuel used. Pumped Storage Schemes
Pumped Storage Schemes Cont.
Use water diverted from a fast-flowing river without damming the river. For areas where there would be need to dam river valley to create a difference in height for the turbines. Run-of-the-river power stations
Supplying electricity can be done through wires. Result in energy loss since wires get hot. Factories dependent on this energy are located closer to the power stations. Some build small-scale power stations near where people live. Issues
Pros: Renewable Emission-free Dams can provide a storm surge barrier Local environmental impact, in contrast to global Regulate water flow
Cons: Construction costs Requires specific locations Harm habitats along rivers Non-continuous