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ENERGY ALTERNATIVES to fossil fuels

ENERGY ALTERNATIVES to fossil fuels. ENERGY- the ability to do work (to make things move). ALL FORMS OF ENERGY FALL UNDER 2 general CATEGORIES : POTENTIAL AND KINETIC Potential energy is STORED energy and/or the energy of position( gravitational or elastic)

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ENERGY ALTERNATIVES to fossil fuels

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  1. ENERGYALTERNATIVES to fossil fuels

  2. ENERGY- the ability to do work (to make things move) • ALL FORMS OF ENERGY FALL UNDER 2 general CATEGORIES: • POTENTIAL AND KINETIC • Potential energy is STORED energy and/or the energy of position(gravitational or elastic) • Kinetic energy is the energy in MOTION. It is the motion of electrons, waves, molecules and substances PRACTICAL USES OF ENERGY ARE TO PROVIDE HEAT, FOR TRANSPORTATION AND FOR GENERATING ELECTRICITY

  3. MANY SOURCES OF POTENTIAL ENERGY • CHEMICAL ENERGY is stored in BIOMASS, NATURAL GAS, COAL, OIL etc (energy stored in the bonds between atoms) • GRAVITATIONAL POTENTIAL ENERGYIN HIGH POSITIONS such as the water in a reservoir behind a hydropower dam

  4. SOURCES OF POTENTIAL ENERGY • NUCLEAR ENERGY in the nucleus of an atom- the energy that holds the protons and neutrons together • STORED MECHANICAL (elastic) ENERGY in objects under the application of a force. For example, compressing a spring or stretching a rubber band

  5. SOURCES OF KINETIC ENERGY • RADIANT ENERGY in sunlight or other electromagnetic waves, such as UV rays which have enough energy to break bonds between atoms • THERMAL ENERGY or heat from the vibration of atoms and molecules. Geothermal is an example • MOTION of a substance from one place to another. Moving air as wind or tidal power are examples

  6. SOURCES OF KINETIC ENERGY • ELECTRICAL ENERGY is the movement of electrons. Lightning and electricity are examples. • SOUND ENERGY is the movement of energy through substances in compressional waves

  7. ENERGY CONVERSIONS • Energy cannot be created but it can be converted or transformed from one kind to another. The total energy is always conserved. This is the 1st law of thermodynamics! • Thermodynamics is the science that keeps track of energy as it undergoes various transformations from one type to another. The 1st law keeps track of the quantity of energy

  8. ENERGY CONVERSION/TRANSFORMATION • Energy always tends to go from a more usable, higher quality form to a less usable, lower quality form. Heat is a lower quality form of energy. • This is the 2nd law of thermodynamics-it keeps track of the quality of energy

  9. Generating electricity • An electric generator is a device that converts mechanical energy to electrical energy • Michael Faraday built the first one. It is always a magnet moved between a coil of wire. Generating electricity is called electric INDUCTION

  10. ALL SOURCES of electricity basically come down to this • Moving the magnet rapidly back and forth through the coils of wire induces the electrons in the wire to move as a current

  11. Generating electricity • Moving the magnet rapidly back and forth through the coils of wire induces the electrons in the wire to move as a current

  12. The technology is old • http://youtu.be/uoQelu7XRjk

  13. ENERGY BASICS:The laws of thermodynamics 1st: energy cannot be created or destroyed, only converted from one form to another (aka law of conservation of energy) 2nd: In all energy conversions, some low quality heat (waste heat) must always be produced. Also known as the law of entropy (disorder). This prevents the construction of any device with 100% efficiency. EVEN photosynthesis is only 1% efficient; incandescent light bulbs only 10%

  14. Photosynthesis In the process of photosynthesis, plants convert radiant energy from the sun into chemical energy in the form of biomass, sugars, proteins and oils (biodiesel).

  15. Use each example below to explain the laws of thermodynamics

  16. PRACTICE QUESTION • Approximately two thirds of the fossil fuel energy we use is lost as waste heat, and the transfer of energy from fuels to electricity is about 35% efficient. This is primarily a consequence of • A) the law of conservation of matter • B) the first law of thermodynamics • C) the second law of thermodynamics • D) the Hubbert curve

  17. Hydroelectricity • Hydroelectric power makes use of the potential energy of water stored in an elevated reservoir. • The gravitational potential energy is larger if the dam is higher. Currently hydropower produces more energy than any other renewable source of energy in the world

  18. Hydroelectric power • The potential energy of the water in the dam is converted to kinetic energy when the water flows down the penstockand is mechanical energy when it turns the turbine connected to the magnet that moves through the wires in the generator. This produces electrical energy as moving electrons.

  19. Disadvantages of hydroelectricity • Creating the dam itself: • Land upstream becomes flooded so habitats are lost or fragmented • Fragmentation prevents species such as salmon and river dolphins from accessing breeding grounds • Sediments accumulate behind the dam, reducing the efficiency of the dam over time • Social costs include displacement of humans from their homes or farms • Water loss due to evaporation because of increased surface area of reservoir

  20. Case study: China’s Three Gorges Dam • The largest dam in the world, biggest power plant. • Displaced 1.13 million people from their land so far. The only two directions for people to go are up and out since everything below the 175m mark will be under water when the reservoir increases

  21. Water pollution from inundated farms add nutrients to the water causing cultural eutrophication • Submerged vegetation also creates methane, a powerful GHG leading to climate change

  22. Advantages of hydroelectricity • Reduces dependence on fossil fuels and the need to mine and burn them • Reduces carbon dioxide emissions to the air • Reduces chances of downstream flooding (unless the dam breaks) • Reservoirs can be used for recreation, agriculture, domestic use and tourism (wildlife viewing)

  23. Famous case study • JAMES BAY hydroelectric PROJECT- • Social impact on the Cree people of Quebec, Canada when their ancestral land was flooded, threatening their livelihood and way of getting food. Cree sued the company and settled for 225 million dollars and rights to govern, hunt, fish and trap on their traditional lands. • Flooding upstream of dams also submerged sacred burial sites

  24. James bay hydroelectric project case study continued • Environmental impact include increased levels of methylmercury, a neurotoxin, in fish due to flooding by the reservoirs behind the hydroelectric dams of mercury contaminated soils • Destruction of caribou feeding grounds. Hydroelectric projects diverted water from some rivers and fragmented habitats used by caribou, black bears, waterfowl, lowering their populations • Alteration of nutrient and salinity levels of the water reaching the bay downstream, affecting marine food chains (you know how…)

  25. Wind energy is the fastest growing source of electricity in the world • The electricity output from a wind turbine rises as a cube of wind speed. For example, doubling wind speed results in x8 electrical power so higher wind speeds produce a great amount of power. • If the wind is too slow, they won’t turn. Too fast they shut down to avoid being damaged. Wind turbines should match the speed and frequency of the wind to maximize power production

  26. Wind resource can vary seasonally and daily • Wind forms as a result of the uneven heating of earth surfaces. For example, high temperatures in the CA central valley and low temperatures along the San Francisco coast cause powerful winds to blow across the Altamont pass in the summer

  27. Uneven heating produces uneven air pressure • Earth surfaces that absorb radiant energy will transfer some of that energy to the air above them as heat. • Heated air rises and creates an area of LOW pressure • Cooler air from a high pressure area moves in to replace the rising air. Moving air is WIND

  28. Coastal and mountain areas have strong winds • The uneven heating of land and water creates strong daily winds (land and sea breezes) along both coasts and around the Great Lakes

  29. Global winds are created in the same way • Uneven heating between the equator and the poles also produce strong winds • These global winds always blow in the same direction. The equator is always the area of LOW pressure. The poles are always areas of HIGH pressure • The rising of heated air and the sinking of cooler air forms a loop called a convection cell

  30. Back up system for when wind is low • Distributing wind turbines across a broad geographic area helps smooth out the variability in wind • Also, electronic controls can be used to allow continued adjustment of electricity output to stabilize power generation

  31. How wind creates electricity • The wind provides mechanical energy to move the blades of the turbine. These are connected to a shaft which rotates the magnet through a coil of wire and generates an electric current

  32. Wind turbines in large numbers are called wind farms

  33. Environmental and societal impacts of wind power • Land use- turbines occupy a large amount of space for roads and equipment, though land underneath can still be used for livestock grazing and agriculture • Evidence of bird and bat death due to collisions with spinning turbines • Sound and visual pollution-some people have complained about the vibrations of turbines and many consider them aesthetically unpleasing (which may impact land value)

  34. Global energy sources • Fossil fuels still power two thirds of the global electricity generation. • Next are biomass (10%), nuclear (6%) and hydroelectric (2%). Over the next 20 years annual electrical energy consumption will increase as developing countries industrialize • “new renewable” energy sources including wind, solar and geothermal

  35. Of the renewables… • Biomass is the leading global source, mostly firewood for poor communities but also with corn grown for fuel (ethanol) in the richer nations • Hydropower is still major. • Wind is the fastest growing energy source. • Solar energy is still too expensive but govt. subsidies may make it competitive

  36. The US uses a mix of energy sources • Most of it is from FOSSIL FUELS (natural gas, oil, coal) which are non-renewable- they are extracted faster than they can be replaced

  37. US energy sources Renewable energy is only 9% of the US energy sources. Most of that goes into generating electricity; some for transportation (natural gas or hydrogen buses) or industrial heat and power

  38. some advantages of renewables… • Most renewable energy sources produce little to no GHG emissions. • Wind and solarrequire essentially no water to operate and so do not compete with agriculture, drinking water systems nor do they pollute water • Creates more jobs for each unit of electricity generated than from fossil fuels

  39. Metric Prefixes to learn for energy… • Micro = 10-6 • Milli = 10-3 3. Centi = 10-2 4. Kilo = 103 5. Mega = 106 6. Giga = 109 …. Of any metric unit (meter, liter, watts, calorie and so on)

  40. Convert watts to kilowatts • How many watts equal 1 kilowatt (kW)? • If an electrical appliance uses 300W, how many kilowatts does it use? • A light bulb uses 60W of power. How many kW does it use?

  41. Some answers… 1. 1kW x 1000W = 1000 watts 1kW 2. 300W x 1kW = 0.3 W 1000W 3. Your answer?

  42. Calculating electrical workKwh • Work = power x time so • Kilowatts x hours • Where kw= kilowatts of energy (power) and hours for the length of time the energy is used • A wind farm generates 12MW of electricity and operates for 2000 hours/yr. How many kWh of electrical energy would the wind farm provide?

  43. measuring efficiency • The efficiency of a device such as a fan can be calculated by comparing the amount of useful energy output (O) to the amount of energy input (I) • If 100J of electrical energy is invested in the fan and only 10J are used to turn the blades, then the efficiency of the fan is only 10/100 or 10%

  44. More efficiency problems • A natural gas power plant is 60% efficient. If one cubic meter of natural gas provides 1000 BTUs of electricity, how many BTUs of waste heat are produced? • Formula triangles are easy to use. Just substitute numbers into the equation. Efficiency= OUT IN

  45. solution • OUTPUT/INPUT = 60% or 0.6 • 1000/input = 0.6 • Let’s use x as input to give 1000/x = 0.6 • So 0.6x = 1000 BTUs coming from the power plant • To find how much is wasted as heat you have to determine the total inputted to the plant then subtract the 1000 BTUs output from it • 0.6x = 1000 0.6 0.6 Answer = 1666.7 BTUs into the plant Wasted is therefore 1666.7-1000 = 666.7 BTUs

  46. Units of energy to memorize • May be measured in calories, joules, kWh or Btu (British thermal unit) • 1 Btu = 252 cal = 1055 J • One calorie is defined as the heat needed to raise the temperature of 1g of water by 1ºC • One Btu is the heat need to raise temperature of 1lb of water by 1ºF • Therm is the unit used to measure the energy in natural gas. 1 therm = 100,000 btu • A kilowatt-hour (kWh) is the energy used to produce 1 kilowatt of electricity for 1 hour. Commonly seen on home electricity bills

  47. Energy Math practice A large natural gas fired electrical power facility produces 15 million kilowatt-hours of electricity each day it operates. The power plant requires an input of 13,000Btus of heat to produce 1kWh of electricity. Determine the Btus of heat needed to generate the electricity produced by the power plant in 24 hours.

  48. solution First change to sci notation, so 15 million kWh = 1.5 x 107 kWh And 13,000 Btu = 1.3 x 104 Btus 1.5 x 1.3 = 1.95 and 7+4 = 11 So the answer is 1.95 x 1011Btus ALWAYS PUT THE UNITS!!!! It is possible to receive no credit if you forget the units.

  49. YOUR TURN • Given that 1kcal of heat is required to increase the temperature of 1kg of water by 1ºC, and that 1 Btu= 252.16 cal • How many kcals would be required to heat 100kg of water by 20ºC for a bath? • How many Btus?

  50. solution • 1kcal heats 1kg to 1ºC, so 100kg would take 100kcal to heat to 1ºC and 100 x 20 to all of that to 20 degrees 100 x 20 = 2000kcal Recall that 1Btu = 252.26 cal = 0.252 kcal So 2000kcal/0.252= 2 x 103kcal/ 2.52 x 10-1 Which is 2/2.52 and 3--1= 0.7936 x 104= 7936 Btus

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