L10-11 Energy Resources I & II (Fall 2024-25) Notes PDF

L10-11: Energy Resources I & II Dr. Cynthia Yau OCES1030 Environmental Science (Fall 2024-25) Offshore Oil Rig in Gulf of Mexico: Photo by Guava Train, Wikipedia 1  Lecture Outline Energy - Kinetic and Potential Energy The Laws of Ther...

L10-11: Energy Resources I & II Dr. Cynthia Yau OCES1030 Environmental Science (Fall 2024-25) Offshore Oil Rig in Gulf of Mexico: Photo by Guava Train, Wikipedia 1  Lecture Outline Energy - Kinetic and Potential Energy The Laws of Thermodynamics Non-Renewable Energy - Fossil Fuels – Coal – Petroleum/Crude Oil – Oil Shales and Tar Sands – Natural Gas – Nuclear Energy Renewable Energy Resources – Wind Energy – Solar Energy – Water/Hydropower – Biomass Energy/Biofuels Energy Conservation Reference: Cunningham et al. (2022), Chapters 2 and 13 2  Energy: The Ability to Do Work Energy is the amount of force or power when applied and can move an object from one position to another Energy can cause heat transfer between 2 objects that are at different temperatures Energy can take many different forms: Heat Light Chemical energy Moved as electricity Power is the rate of energy flow or the rate of work done: e.g. one watt (W) is one joule per second.  Kinetic Energy The energy contained in moving objects Examples Water flowing over a dam A rock rolling down a hill Wind blowing through the trees Electrons speeding around the nucleus of an atom Potential Energy The stored energy that is available for use. Examples Water stored behind a dam A rock held at the top of a hill Chemical energy stored in food / gasoline Kinetic Energy 6  The Laws of Thermodynamics Thermodynamics is the study of the relations between heat, work, temperature, and energy. The laws of thermodynamics describe how the energy in a system changes. First Law of Thermodynamics Energy can neither be created nor destroyed under normal conditions However, energy may be transformed E.g. Potential energy → Kinetic energy + Heat Second Law of Thermodynamics With each successive energy transfer or transformation in a system, less energy is available to do work E.g. chemical energy in gasoline → kinetic energy + Heat - I.e. some of the energy is degraded to lower quality forms, or it dissipates and is lost. Disorder in the universe (or entropy) always increases, thus efficiency of any process will always be less than 100%. Kinetic energy Friction → heat 8  Energy for Life A constant supply of energy is needed to keep biological processes running. Nearly all life on earth  Photosynthesis The Sun = the ultimate energy source Sun‘s energy captured by green plants (primary producers) Photosynthesis - Green plants create carbohydrates and other compounds using just sunlight, air, and water Some organisms  Chemosynthesis Extract energy from inorganic chemical compounds (e.g. hydrogen sulfide, H2S) Chemosynthesis  ENERGY RESOURCES Modern life runs on energy. Electricity and abundant fuel make our lives easier by providing heating, cooling, and transportation. We use energy to grow and prepare food, to work at our jobs, and to entertain ourselves. Fossil fuels—oil, gas, and coal—provide the bulk of this energy. Hydropower and nuclear power supplement these, and increasingly wind, solar, and other renewable forms of energy are part of our standard energy supply. 10 Energy use in the U.S. Largest share is used by industry Residential use = 22% Commercial use in HK = 42% Residential use -= 21% 11  Energy Resource Use in Hong Kong Non-Fossil Fuels = nuclear & renewable energy Source: https://www.hk2050isnow.org/energy/ “Hong Kong will continue to phase down coal [by 2030] for electricity generation and use more natural gas and increase non-fossil fuel sources, which will enable Hong Kong to reduce carbon emissions significantly in the medium term, representing a very major commitment”. www.climateready.gov.hk 12  I. NON-RENEWABLE ENERGY RESOURCES Non-renewable energy comes from sources that are finite and will run out or will not be replenished in our lifetimes - or even in many, many lifetimes. Their big advantage: → stable supply of energy Most non-renewable energy sources are fossil fuels: coal, petroleum, and natural gas. Carbon is the main element in fossil fuels. For this reason, the time period that fossil fuels formed (about 360-300 million years ago) is called the Carboniferous Period. 13  Carboniferous Forest (reconstruction) Most of the richest fossil fuel deposits date to about 300 million years ago in the Carboniferous Era. The Earth’s climate was much warmer and wetter than it is now and giant plants growing in swamps dominated many parts of the Earth’s land surface. YouTube video: “Fossil Fuels 101” (2:42 mins) 14 https://www.youtube.com/watch?v=zaXBVYr9Ij0  Fossil Fuels Fossil fuels are organic (carbon‐based) compounds derived from decomposed plants, algae, and other organisms buried in rock layers for hundreds of millions of years. Plants, algae, and animals die Decomposed and buried in sediments over millions of years (most were laid down 286 million ‐ 360 million years ago) high pressures & temperatures Organic chemicals being concentrated and transformed into fossil fuels Fossil fuels are all harnessed for the chemical energy they store.  Fossil Fuels (cont) Fossil fuels are non-renewable resources: - a natural resource that cannot be readily replaced by natural means at a pace quick enough to keep up with consumption - thus, are considered finite resources Coal (solid) Petroleum / Crude Oil (liquid) Oil Shales and Tar Sands / Oil Sands (semi‐solid) Natural gas (gas) Energy Resources from the Earth’s Crust  Coal A solid fossil fuel consisting of carbon (main component, mostly of plant matter), sulphur, mercury, and radioactive substances. Photo: CNBC Formation of Coal Prolonged heat and pressure over 300 million years help form different types of coal Peat Lignite Bituminous Anthracite Coal Reserves Are Vast These are explored and mapped reserves, but may not necessarily be economic to extract at today’s prices. World coal deposits are enormous – 10x greater than conventional oil and gas resources combined. Most coal deposits are in N. America, Europe and Asia with U.S., Russia, and China accounting for 2/3 of all proven coal reserves. Total resource: ~10 trillion metric tons, or several thousand years’ supply! Extraction of Coal Photo: Egypt Independent But coal mining is a dirty, dangerous activity. Coal is deep underground Tunnels and shafts Coal mine tunnel Coal is close to earth’s surface Strip mining Photo: Decoding Biosphere Environmentally destructive Strip mining, US  Coal Burning and Air Pollution Every year, ~1 billion tons of coal burned in the U.S. releases: ~a trillion metric tons of CO2 = ~1/2 of the industrial CO2 released by the U.S. each year Coal also contains toxic impurities that are released into the air during combustion Mercury, arsenic, chromium, lead, uranium Coal-fired steel plant, Inner Mongolia  Petroleum or Crude Oil A thick liquid consisting of hydrocarbons (main component), sulphur, oxygen, and nitrogen. Petroleum sample Petroleum is formed when large quantities of dead marine organisms, mostly zooplankton (animal plankton) and algae, are buried underneath rock and subjected to both prolonged heat and pressure. Petroleum and Natural Gas Formation 24  Increase in boiling points Refining Crude Oil Based on their boiling points, components of crude oil are refined and removed at various levels in a giant fractional distillation column The most volatile components with the lowest boiling points and lowest viscosity are removed at the top of the column e.g. gasoline Miller (2003)  Oil Supplies Estimates of the recoverable oil supplies have expanded dramatically, as techniques developed for obtaining oil from: e.g. deep in the ocean, extracted by drilling from offshore platforms – potentially hazardous, and risks of oil spills. In the U.S. Long dependent on oil imports, now produces more oil than it imports Offshore oil drilling platform “Deepwater Horizon” disaster 2010  Photo: National Geographic Natural Gas A mixture of methane (main component), ethane, propane, butane, and hydrogen sulphide (highly toxic). Uses of natural gas Heating Cooking Lighting Providing base ingredients for industrial products such as plastic, fertilizer, and fabrics  Natural Gas: Growing in Importance The world’s second‐largest commercial fuel ~1/4 of global energy consumption Produces only 1/2 as much CO2 as coal Often used as a transition fuel towards renewable energy >1/2 of all the world’s proven natural gas reserves are found in: Middle East Russia Current gas reserves: 60‐year supply at present usage rates Extraction of Natural Gas When a natural gas field is exploited (or tapped) Methane gas Processed (e.g. cleansed of toxic H2S and other impurities) Pumped into pressurized pipelines for distribution (e.g. Towngas) Propane and butane gases Liquefied and removed as liquefied petroleum gas (LPG) (stored in pressurized tanks, mainly used in rural areas not served by natural gas pipelines) Photo: CLP Liquefied Natural Gas (LNG) is natural gas that has been cooled down to liquid form for ease and safety of storage and transport. LNG receiving terminal, Hong Kong  Nuclear Energy Nuclear energy is considered non-renewable since nuclear fuels are a finite material mined from the ground (and can only be found in certain locations). The main nuclear fuels are uranium and plutonium, these are radioactive chemical elements which are unstable. Uranium‐235 (235U) An isotope of uranium (~0.72% of natural uranium) Fissile - can sustain a fission chain reaction The only fissile isotope found in significant quantity in nature  How Do Nuclear Reactors Work? Radioactive uranium atoms: Unstable Struck by a high‐energy neutron Nuclear fission (splitting) Releasing energy and more neutrons Self‐sustaining chain reaction YouTube video (2:12 mins) “What is Nuclear Energy?” https://education.nationalgeographic.org/resource/what-nuclear-energy  Nuclear Reactors ‐ Design 70% of the world’s nuclear plants: Pressurized Water Reactors Water circulates through the core, absorbing heat as it cools the fuel rods This primary cooling water is heated to 317˚C, reaches a pressure of 2,235 psi It is then pumped to a steam generator, where it heats a secondary loop A turbine Steam from the secondary loop drives a high‐speed turbine that produces electricity in a generator potential energy of the steam → kinetic energy → mechanical energy (rotation of turbine shaft) Nuclear Reactors (cont.) Efficient form of energy production, but expensive construction costs Do not produce CO2 Worldwide, ~440 reactors in use U.S.: 104, ~8% of U.S. energy supply Half of the U.S. plants > Nuclear power plant, Germany 30 years old Approaching the end of their expected operational life Daya Bay, China – supplies 25% of HK’s electricity consumption Radioactive Waste: Lacking Safe Storage One of the most difficult problems of nuclear energy is the safe disposal of radioactive wastes produced during mining, fuel production, and reactor operation. Spent fuel is stored temporarily in large, above-ground ‘dry casks’. Safety is expensive!