L7 Energy and the Environment (GEOG1005) PDF

L7 Energy and the environment GEOG1005 Geography and the Contemporary World Dr. GUO Meiyu OUTLINE Basic concepts Environmental problems Renewable energy NATURE OF ENERGY Energy is involved when: a bird flies. a bomb explodes. rain falls from...

L7 Energy and the environment GEOG1005 Geography and the Contemporary World Dr. GUO Meiyu OUTLINE Basic concepts Environmental problems Renewable energy NATURE OF ENERGY Energy is involved when: a bird flies. a bomb explodes. rain falls from the sky. electricity flows in a wire What is energy? Energy can be defined as the ability to do work (做功). If an object or organism does work, the object or organism uses energy. ENERGY BASICS Thermodynamics (熱力學) - study of the energy and work of a system. Conservation of matter - First Law of Thermodynamics. Second Law of Thermodynamics - when energy changes from one form to another form, or matter moves freely, entropy (disorder) in a closed system increases. Differences in temperature, pressure, and density tend to even out horizontally after a while. FORMS OF ENERGY The five main forms of energy are: Heat Chemical Electrical Nuclear Mechanical  ENERGY CONVERSIONS Energy can be changed from one form to another. Changes in the form of energy are called energy conversions. All forms of energy can be converted into other forms. The sun’s energy through solar cells can be converted directly into electricity. Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).  ENERGY CONVERSIONS In an automobile engine, fuel is burned to convert chemical energy into heat energy. The heat energy is then changed into mechanical energy. Chemical → Heat →Mechanical STATES OF ENERGY The most common energy conversion is the conversion between potential and kinetic energy. All forms of energy can be in either of two states: Potential: stored energy Kinetic (動能): the energy of motion GRAVITATIONAL POTENTIAL ENERGY (G.P.E) Potential energy that is dependent on height is called gravitational potential energy. A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy. If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board. KINETIC ENERGY  The energy of motion is called kinetic energy.  The faster an object moves, the more kinetic energy it has.  The greater the mass of a moving object, the more kinetic energy it has.  Kinetic energy depends on both mass and velocity.  KINETIC-POTENTIAL ENERGY CONVERSION As a basketball player throws the ball into the air, various energy conversions take place. Ball slows down Ball speeds up LAW OF CONSERVATION OF ENERGY  Energy can be neither created nor destroyed by ordinary means.  It can only be converted from one form to another.  If energy seems to disappear, then scientists look for it – leading to many important discoveries.  In 1905, Albert Einstein said that mass and energy can be converted into each other.  He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created. ENVIRONMENTAL PROBLEMS NON-RENEWABLE RESOURCES  Fossil fuels, coal, oil, and natural gas, are the most common example of nonrenewable energy resources.  Formed from fossils, the partially decomposed remains of once living plants and animals  Took millions of years to form  When burned for energy, they release pollutants and carbon dioxide into the atmosphere. HOW FOSSIL FUELS FORMED NON-RENEWABLE RESOURCES  Coal  Formed by fossilised plants  Mined from seams of coal found between rock layers in the earth  Burnt to provide heat or electricity  Generates pollutants and greenhouse gases (CO2)  Oil  Carbon-based liquid formed from fossilised animals  Pumped out from reservoirs between seams of rock in the earth  Widely used in industry and transport  Generates pollutants and greenhouse gases (CO2) NON-RENEWABLE RESOURCES  Natural Gas  A hydrocarbon gas primarily containing methane and other gases  Released through pipes sunk into the seams of rock where it is trapped  Often used for heating  Expected to last 70 years  Generates pollutants and greenhouse gases (CO2)  Biomass (can be renewable or non-renewable)  Generated from decaying plant or animal waste  Chemicals can be used for fuel in diesel engines or organic material can be burned for heat and electricity NON-RENEWABLE RESOURCES  Wood (can be renewable or non-renewable)  Obtained from felling trees  Burnt to provide heat or light  Can be renewable if trees are replanted, but if they are not replaced then it is a non-renewable energy sources  Generates pollutants and greenhouse gases (CO2)  Nuclear  A small amount of radioactive material can produce a lot of energy  Does not generate atmospheric pollutants or greenhouse gases  Nuclear waste is highly toxic and must be safely stored for hundreds or thousands of years  Leakages and accidents can be devastating to people and the environment (e.g. Chernobyl, 1986)  OIL USE BY NATION People in the U.S. use far more energy—especially energy from oil— than people in any other nation. Per capita oil consumption United States 31 M W h Australia 24 M W h Norway 20 M W h United Kingdom 13 M W h Chile 11 M W h Brazil 6 MWh South Africa 6 MWh China 5 MWh India 2 MWh 0 MWh 5 MWh 10 M W h 15 M W h 20 M W h 25 M W h 30 M W h Source: Our World in Data based on BP Statistical Review of World Energy & U N Population Division OurWorldlnData.org/energy C C BY GLOBAL COAL OUTPUT  By ​DU JUAN | chinadaily.com.cn | Updated: 2021-11-05 11:25 https://aqicn.org/city/ 21/40  What is the smog in China? Smoke + fog Particulate Matter 2.5 (PM2.5) Major components of PM2.5 in Beijing Diameter < 2.5 𝜇𝑚 Source: US EPA, https://www.epa.gov/pm-pollution/particulate-matter-pm-basics Source: Beijing Municipal Environmental Protection Bureau (2014) 22/40  Where does PM2.5 come from? Source: Beijing Municipal Environmental Protection Bureau (2014) 23/40  8% 2% 8% 58% 20% “Coal-to-gas” Policy (2013) 24/40  Primary energy consumption in China in 2019 ▪ China’s Energy Development Strategy Action Plan (2014-2020)  Natural gas consumption: at least 10% by 2020 ▪ Primary energy consumption 2019:  Coal: 58%  Natural Gas: 8% ▪ Address air pollution problems ▪ Reduce GHG emissions (Commitment: Peak by 2030, Neutral by 2060) 25/40 Natural Gas in China Shale gas? 42% Data Source: BP Statistical Review of World Energy 2021 26/40 https://www.youtube.com/watch?v=Tudal_4x4F0 CONSEQUENCES OF NATURAL GAS USE  Natural gas burns much cleaner than other fossil fuels, meaning that it causes less air pollution.  Natural gas also produces less carbon dioxide than other fossil fuels do for the same amount of energy, so its global warming effects are less.  Processing natural gas removes almost everything except the methane.  Drilling for natural gas can be environmentally destructive.  FOSSIL FUEL RESERVES Fossil fuels provide about 85% of the world's energy Worldwide fossil fuel usage has increased many times over in the past half century (coal - 2.6x, oil - 8x, natural gas - 14x) EFFECTS OF FOSSIL FUEL PRODUCTION Fossil fuels are hydrocarbons containing traces of nitrogen, sulfur and other elements. Fossil fuels are produced by mining or drilling. Considerable environmental damage results from mining and drilling... Surface mining for coal often results in vegetation loss, stream and soil acidification, road damage, etc. FOSSIL FUEL PROCESSING HAS ENVIRONMENTAL CONSEQUENCES…  Acid rain  Indoor Air Pollution  CFC Problem  Stratospheric Ozone Depletion  Principal Greenhouse Gases RENEWABLE RESOURCES RENEWABLE RESOURCES  Solar, water, wind, biomass, and geothermal  Either virtually limitless like the Sun, which will continue to shine for billions of years, or will be replaced faster than we can use them RENEWABLE RESOURCES  Problems: expensive, competitive uses, cause environmental problems.  As the technology improves and more people use renewable energy, the prices may come down.  At some point, even if renewable energy costs are high, nonrenewable energy will be even more expensive.  Ultimately, we will have to use renewable sources. The UK uses renewable energy resources to generate heat and electricity. Renewable energies account for only 0.8% of the total electricity supply 2022 in Hong Kong. RENEWABLE RESOURCES Why do we need renewable energy resources? Why can’t we just continue to use non-renewable resources? RENEWABLE RESOURCES CO2 is at 407ppm (Oct 2018) increased by 90ppm in the last 70 years Global warming ~1.1°C in the past 200 years Ocean acidification Rising sea level ~3.2mm each year Decreasing ice sheet mass Retreating glaciers Decreasing Arctic ice at a rate of 13% each decade Renewable energy is crucial for mitigating climate change  RENEWABLE RESOURCES:WIND Propeller Wind farm Blade Strong winds Clear hilltop Turbines in prevailing wind direction Nacelle containing generator Tower Wind turbine  RENEWABLE RESOURCES:WIND The amount of power, and therefore electricity, a wind turbine can produce is largely based on wind velocity using this equation: Higher wind speed = lots more power Power = ½ ρAV3 Larger wind turbine = more power ρ = air density; ~1 kg m3 Power is measured A = swept area (π r2 ) in Watts V = velocity (m s-1)  RENEWABLE RESOURCES:WIND UK has 9,220 wind turbines (Oct 2018) with a capacity for 20.1 gigawatts – 6th largest producer of wind power in the world In 2017, 17% of UK electricity was generated from wind power (29% by renewables in total)  RENEWABLE RESOURCES: SOLAR Thermal solar panels are used to generate heat energy, Photovoltaic (PV) cells made from silicon turn sunlight directly into electricity photons 3.4% of total electricity was generated by Solar PV in the UK in 2017 (29% by renewables in total) 25.7 MW Lauingen Energy Park in Bavarian Swabia, Germany  RENEWABLE RESOURCES: SOLAR South of UK has ‘solar potential’ equal to Germany which generates 7% of electricity from solar PV. Solar panels are expensive. You need a lot of them and they require rare metals such as cadmium and indium. An average UK house uses around 3kW of energy each year – you need 12-15 solar panels to generate this much power. UK solar energy potential https://www.youtube.com/watch?v=QfZGqVhqdxc  RENEWABLE RESOURCES: GEOTHERMAL Geothermal energy = heat energy from the Earth Decay of radioactive elements and residual heat from planetary formation 4.5 billion years ago Water is pumped down into hot rock where it is heated. Steam can then be used to heat buildings directly or to generate electricity by spinning a turbine.  RENEWABLE RESOURCES: GEOTHERMAL ~ 190 ˚C granite 4.5km beneath Cornwall. United Downs Geothermal Energy Project has funding to build a pilot geothermal energy plant 10 megawatts (MW) of electricity and 55MW of heat. Geothermal energy beneath Cornwall could meet all of Cornwall’s demand for electricity and up to 20% of the UK’s demand.  RENEWABLE RESOURCES: HYDROELECTRIC Hydroelectric power harnesses the kinetic energy of running water. Water flows downwards with gravity to spin a turbine. Hydroelectric More reliable than solar and wind dam power. Hydroelectric dams are very Reservoir of expensive and can harm wildlife. water 1.5% electricity from hydroelectric schemes in the UK (29% total) Generator Turbine RENEWABLE RESOURCES: HYDROELECTRIC 705 GWh per year Cruachan Power Station, Argyll and Bute, Scotland ICELAND  ICELAND ICELAND Iceland lies on the Mid Atlantic Ridge a region of sea floor spreading = lots of hot rocks! Annual rainfall 2,000mm (HK ~2400 mm/year) 600 hot springs and 20 high-temperature steam fields >150 °C. Nesjavellir Geothermal Power Station  ICELAND 85% of Iceland’s heating and 27% of electricity comes from geothermal energy. 70% of Iceland’s electricity comes from hydropower from glaciers and rivers. Hydropower saved Iceland an ~ $8.2 billion from 1970 to 2000 and lowered its CO2 emissions by 37%. Nesjavellir Geothermal Power Station Still dependent on fossils fuels for ships, cars and buses –actually one of the highest emitters of CO2 per capita. Research into hydrogen fuel cells to power buses and cars. 100% RENEWABLE ENERGY?