Environmental Science

• Energy sources


  • Nonrenewable
  • Renewable
• Nonrenewable energy sources


  • Fossil fuels
  • Nuclear power
• Solid waste


  Any unwanted or discarded material people produce that is not liquid or gas
• Fossil fuels

  • Coal
  • Natural gas
  • Oil
• Net energy


  Amount of energy available from a resource minus the amount of energy needed to make it available
• Municipal waste

  Solid waste produced by individuals or non-industrial businesses
• Nonrenewable


  Resource that exists in a fixed amount (stock) in the earth's crust and has the potential for renewal by geological, physical, and chemical processes taking place over hundreds of millions to billions of years
• Industrial waste


  Solid waste produced by mines, farms, & industries
• Net energy


  Amount of energy available from a resource minus the amount of energy needed to make it available
• Nonrenewable


  Resource that exists in a fixed amount (stock) in the earth's crust and has the potential for renewal by geological, physical, and chemical processes taking place over hundreds of millions to billions of years
• Renewable


  Energy that comes from resources that are replenished by natural processes continually or in a relatively short time
• Carbon dioxide (CO2)


  Powerful greenhouse gas, that comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and natural processes like volcanic eruptions

  
• Methane (CH4)


  Powerful greenhouse gas that is the primary component of natural gas
• Climate change


  Long-term shifts in temperatures and weather patterns. Such shifts can be natural, due to changes in the sun's activity or large volcanic eruptions. Since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels like coal, oil and gas that emits large quantities of greenhouse gasses
• Energy production is a major source of greenhouse gas emissions
• Nonrenewable energy sources


  • Fossil fuels
  • Nuclear power
• Renewable energy sources


  • Hydropower
  • Solar
  • Wind
  • Biomass
  • Geothermal
  • Nitrogen
• Electricity generation is steadily increasing
• Fossil fuel-derived electricity accounts for 61% of our electricity production

  
• Renewable energy sources only account for 30% of our electricity production, mostly through hydropower
• Fossil fuels


  Products of partial or complete decomposition of plants and animals; occurs as crude oil, coal, natural gas, or heavy oils as a result of exposure to heat and pressure in the earth's crust over millions of years

  
• Demand on fossil fuels has increased in the past decades

  
• Fossil fuels are nonrenewable energy sources, so they will run out eventually

  
• Coal


  • Net energy yield: High
  • Production cost: Low
  • Energy generation method: combustion + turbine
• Environmental impacts of coal

  • Land degradation via mining
  • Emissions: High (CO2)
  • Water and air pollution
  • Groundwater near coal plants is contaminated, the EPA relaxed regulations in 2019
• Natural gas


  • Net energy yield: Medium
  • Production cost: Low
  • Extraction method: horizontal drilling and fracking
• Environmental impacts of natural gas

  • Seismic activity (earthquakes)
  • Emissions: Burns less CO2 than oil and coal, but generates methane (CH4)
  • Contaminated water sources
• Crude oil (petroleum)


  Black, gooey liquid containing a mixture of combustible hydrocarbons along with small amounts of sulfur, oxygen, and nitrogen impurities

  
• Crude oil (petroleum)


  • Net energy yield: Medium
  • Production cost: Low
  • Emissions: High (CO2)
  • Requires refining, which generates a variety of products, including petrochemicals

  
• Environmental impacts of oil

  Water pollution due to oil spills
• Nuclear energy


  Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion
• Nuclear energy


  • Net energy yield: Low
  • Production cost: High (build cost)
  • Extraction method: Uranium mining
  • Emissions: 1/6 of coal's CO2 emission
• Environmental impacts and concerns of nuclear energy

  • Long-lived radioactive waste
  • Fear of accidents
  • Role in spread of nuclear weapons technology
  • Fukushima Daiichi Nuclear Power Plant Accident in Japan
• Hydropower


  Utilizes turbines to convert the kinetic energy of flowing water into electricity, a process that can be sustained indefinitely due to the continuous replenishment of water within the water cycle
• Hydropower is the world's leading renewable energy source
• Hydropower


  • Net energy yield: High
  • Production cost: Low
  • Emissions: Low operational, some CH4 emissions from reservoirs
• Environmental impacts and concerns of hydropower

  • Land disturbance and displacement of people, which can affect downstream ecosystems
  • Solution: fish ladders
• Solar energy (solar cells)


  Converts solar energy directly into electrical energy, a process that can be sustained indefinitely due to the continuous supply of energy from the sun
• Solar energy


  • Net energy yield: Low (but improving)
  • Production cost: Modest to high
  • Emissions: (Almost) none
  • Low land disturbance
  • Limited by sunlight availability (needs at least 60% sunlight daily)
• Environmental impacts and concerns of solar energy

  Mining resources (cobalt)