APES Unit 6 - Energy Sources

• Fossil fuels and nuclear fuel are both nonrenewable energy resources
• Fossil fuels are finite and nonrenewable because it will take tens of millions of years for new ones to form
• Human civilization is depleting fossil fuels faster than they can replenish
• Prefixes to know:

  • Kilo: 1000
  • Mega: 1,000,000
  • Giga: one billion
• Renewable energy resources: sources of energy that are infinite
• Potentially renewable: energy sources that can be regenerated indefinitely as long as it is not overharvested examples are wood and biofuel
• Nondepletable: an energy source that cannot be used up, like wind, solar, hydroelectric, geothermal
• Oil, coal, and natural gas comprise 80% of total energy use worldwide in 2020
• Renewable energy makes up 15% of total energy use worldwide
• Energy consumption in the US is five times greater than the world average
• People in developed countries use over 40% of the world's energy annually, despite only 20% of the population living in developed countries
• China has the greatest total energy consumption, while the US has the greatest per capita energy consumption
• Commercial energy sources are energy sources that can be bought and sold, such as coal, oil, and natural gas
• Subsistence energy sources are gathered by individuals for their own use
• In the US, energy use mainly comes from fossil fuels, with nuclear fuel and renewable energy being approximately equal
• Industry is the sector that uses the most energy, followed by transportation
• 15% of energy is exported from other countries to the US
• Energy intensity is a measure of energy use and productivity, calculated as energy use per unit of gross domestic product (GDP)
• Energy intensity has decreased in the US, but overall energy use continues to rise due to population growth
• Fossil fuel combustion is a chemical reaction between fossil fuels and oxygen, resulting in the production of carbon dioxide, water, and released energy
• The Hubbert curve is a graph that illustrates oil use and predicts when world oil production will peak and when oil reserves will be depleted
• Peak oil is the point at which oil extraction and use would increase steadily until roughly half of the supply is depleted
• A truly sustainable approach to energy use should include both energy conservation (finding and implementing ways to use less energy) and energy efficiency (ratio of the amount of energy used to the total amount of energy)
• Both energy conservation and energy efficiency are the least expensive and most environmentally sound options to maximize energy resources
• Energy efficiency and conservation are easier since it isn’t a switch to a completely new technology
• Energy efficiency refers to both the efficiency of the process of getting the fuel, and the process of converting the fuel into the work that is needed
• Energy is lost at every stage from transportation to processing and disposal
• Energy return on energy investment (EROEI) is the amount of energy obtained from the fuel divided by the energy invested to obtain the fuel
• A larger EROEI suggests a more efficient process
• Carbon neutral: an activity that doesn’t change atmospheric carbon dioxide concentrations
• Fossil carbon: old carbon contained in fossil fuels
• Modern carbon: the carbon in biomass that was recently in the atmosphere (basically carbon that’s been in circulation and hasn’t been in the ground like fossil carbon)

  • Theoretically, burning modern carbon doesn’t contribute to C02
  • (sometimes isn’t always carbon neutral from gathering the modern carbon though)
• Biofuels: liquid fuels like ethanol and biodiesel created from processed or refined biomass
• All fossil fuel and most renewable energy sources come from the Sun
• Major fuel types and their uses:

  • Wood: used for heating, cooking, and in paper industries. Also used to make charcoal
• Coal: formed from plant remains millions of years ago. Used for electricity. Peat, a precursor to coal, can also be burned for fuel
• Types of coal:

  • Lignite: "brown coal," 60-70% carbon, newest formed
  • Bituminous coal: "black or dark brown coal," contains bitumen/asphalt; up to 80% carbon and can be broken by hand
  • Anthracite: "hard coal," greater than 90% carbon. Highest energy per volume, fewest impurities, oldest
• Natural Gas: 80-90% methane and 5-20% ethane, propane, and butane. Burns cleanly except for CO2 emissions. Used for electricity, industry, nitrogen fertilizers, cooking, clothes dryers, water heaters. Can be liquefied for portable barbecue grills
• Crude Oil: mixture of oil, gasoline, kerosene, water, sulfur. Also known as oil or petroleum
• Tar Sands: slow-flowing deposits of bitumen or asphalt mixed with sand, water, and clay. Can be extracted into crude oil. More energy-intensive to mine than crude oil. Extraction contaminates water