Unit 6 - Energy Resources & Consumption

6.1 Renewable & Nonrenewable Resources

• ==nonrenewable==: the fixed amount that cannot be replaced easily (within a humans lifespan)
    * has finite amount
      * ex. petroleum, gasoline, fossil fuels, nuclear energy (uranium)
• ==renewable==: can be replenished naturally at a reasonable rate
    * reusable, can be used indefinitely with proper management
      * ex. biomass, hydroelectric, solar, wind, waves, geothermal

6.2 Global Energy Consumption

• energy resources are unequally distributed among LDCs and MDCs
    * 20% of population = 80% of energy
    * MDCs use a lot more energy than LDCs
• fossil fuels - major/dominant source of energy (before coal)
    * ie. petroleum, coal, oil, gas
• sustainable energy sources are not projected to be major energy sources until 2040
• MDCs are very reliant on fossil fuels
    * increase in country development = increase in energy consumption
    * industrialization = demand for energy
      * due to machinery that increases efficiency and productivity
• factors for energy use depend on the country
    * availability (what sources are present?)
    * price (supply and demand)
    * government regulation (taxes, subsidies)

6.3 Fuel Types and Uses

• wood and charcoal: used in LDCs due to ease of access and little to no processing
    * abundant in these countries
    * causes soil degradation from less CO2 and deforestation
• peat: decomposed organic material that is burned for fuel
    * a precursor to coal (can be pressurized to become coal)
• there are many types of coal
    * lignite: low heat capacity, low sulfur, high moisture (worst)
    * bituminous: most commonly used, high heat capacity & sulfur
    * anthracite: best quality, high heating capacity, low sulfur (best)
• cleanest fossil fuel: natural gas
    * does not release as many harmful emissions (only releases CO2 and CH4)
    * easily transportable
• crude oil is extracted from sand, water, and bitumen in tar sands
    * not ideal for processing
    * expensive and inefficient
• specialized types of fuel: gasoline, diesel, jet fuel, heating oil, etc.
    * based on having different boiling points in refineries
• cogeneration: fuel sources used for heat + electricity

6.4 Distribution of Natural Energy Resources

• natural energy resources: coal, oil/petroleum, natural gas, ores/uranium
    * energy sources found all over the world
      * ex. Australia, Canada, Russia, etc.
• main energy source depends on energy sources in the country
• natural gas and other fossil fuels formed from pressure and heat of organic matter over millions of years

6.5 Fossil Fuels

• combustion: chemical process from burning fuel
    * fuel + O2 → CO2 + H2O
    * includes coal, oil, and natural gas
• pulverization: crushes the coal to powder → burning/combustion: done in boiler → steam in a turbine to generator → generator: converts energy to electricity (water for boiling, water for cooling)
• causes lots of environmental problems
    * destroying habitat through mining
    * pulverized coal harmful to respiratory systems and flammable
    * water depletion needed for cooling/heating
    * CO2 production → impact on climate change
    * dispersion of pollutants (mercury, sulfur)
• oil/natural gas: formed from organic matter caught under earth material
    * decomposition → gas, petroleum
    * requires mechanical pumping, drilling, and hydraulic fracturing
    * habitat destruction, potential for oil spills
• natural gas: found at many rock levels
• coal mining: dug from underground
    * surface mining: dig some land to get coal a little bit underneath
    * subsurface mining: requires machinery to dig deep into earth to find coal; habitat disruption, water contamination, frequent earthquakes
• hydrologic fracturing (fracking): method to get natural gas from the ground and bypassing groundwater reserves
    * well is made → pipe is inserted → fracking fluid (volatile compounds) → gas flows into pipe
    * causes wells/pipes to contaminate water/habitat destruction
    * VOCs harmful to the ground
    * gas leakage into atmosphere
    * causing earthquakes from added pressure
    * water depletion

6.6 Nuclear Power

• nuclear fission: usage of uranium 235 → electricity
    * splits the nucleus into separate parts to release energy (chain reaction, repeating process)
    * emits radioactive energy alongside heat
    * is not safe even after long periods of time
    * overuse: unable to create enough heat
    * remains radioactive for up to 24k years → prone to waste leaking into environment
      * ex. three-mile island (partial plant meltdown), chernobyl (full plant meltdown), fukushima (earthquake trigged nuclear explosion)
• uranium placed in fuel rods → struck by outside neutron → heat releases from uranium splitting up → heat generates steam → turns turbine → powers generator → electricity
• water can be reused through condensation (steam cools down)
    * pros: low chemical gas emissions, high power output, low cost, no mining for fossil fuels, no air pollutants
    * cons: hazardous/accident, thermal pollution, high initial cost, emissions from mining uranium, a nonrenewable source
• half-life: measure of the time for an atomic nuclear to decay

6.7 Energy From Biomass

• biomass stores energy from the sun
    * leading renewable energy source
    * converted during photosynthesis, stored in glucose molecules
    * used primarily in many LDCs
      * ex. wood, peat, charcoal, crop residue, manure
    * pros: low cost, easily accessible, used for heating/cooking
    * cons: causes many types of air pollutants, amplifies health effects (ie. respiratory illness) due to air pollutants indoors, tree for fuelwood → deforestation
• biofuels: liquid fuels made from biomass that can replace fossil fuels
    * ethanol: made from fermented plant-based sugars → alcohol
      * typically combined with gasoline (gasohol)
      * sources: corn, sugarcane, sugarbeets
    * biodiesel: modified oil from plants
      * can replace diesel fuel
      * sources: soybeans, oil palms, rapeseed
    * pros: carbon neutral, renewable, domestically produced
    * cons: low net energy, increases fossil fuels for harvesting and deforestation

6.8 Solar Energy

• photovoltaic solar energy (PV): sunlight → electricity
    * sunlight hits cell → releases electrons → releases electricity
      * pros: reduces habitat destruction, flexibility in application (ie. off the grid)
      * cons: use limited to sunlight availability, limited cell lifespan, expensive, may hurt fragile deserts
• active/concentrated solar power: red liquid heats up from sun → water turns into steam → steam turns the turbine → turbine turns a generator
    * also produces heat through house heating system
      * pros: flexibility in application
      * cons: expensive, maintenance, may hurt fragile deserts, requires high solar intensity
• passive solar: sunlight coming through windows and other parts of your home
    * produces heat, windows are strategically placed to minimize heat in summer months and maximize sunlight during winter months
      * pros: cheap, low maintenance
      * cons: difficult to implement, cannot be collected or stored

6.9 Hydroelectric Power

• kinetic energy from movement of wires and magnets in systems
• dams/reservoirs: water has kinetic energy (KE) → KE to spin turbine → KE to spin generator
• micro hydro power: utilizes single rivers/canals as energy source
    * similar to dams/reservoirs but much smaller scale and goes through powerhouse
• tidal power: KE from tides spins turbine underwater
    * pros: no air pollution or waste, inexpensive to maintain, the reservoir provides other services
    * cons: very expensive to construct, habitat destruction before/after building dams, disruptions migration of aquatic species, increased risk of flooding, disrupts natural river flows
      * ex. china three gorges dam

6.10 Geothermal Energy

• geothermal: using heat from Earth’s core that comes up from the crust
    * water in the injection well underground→ water turns into steam from internal heat → steam rises → KE steam turns a turbine → generator → electricity
    * pros: no CO2 emissions, not dependent on weather conditions
    * cons: limited access based on location, hydrogen sulfide release, depletion of heat, groundwater impact
• home heating: uses pump to bring heat from underground into house/building

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6.11 Hydrogen Fuel Cell

• uses hydrogen as fuel to replace nonrenewable sources
    * reaction between hydrogen & oxygen → electric current
    * open container used to refuel battery with hydrogen fuel & oxygen
• hydrogen from water: electrolysis → electricity splits water into hydrogen and oxygen
• hydrogen from natural gas: splitting methane using heat → CO2 pollution
    * decreases net energy of hydrogen as a fuel source
    * net energy: amount of energy produced by the source - the energy used or lost to generate said energy
• first reaction layer: H2 added to cell → splits protons/electrons → electrons create electric current & protons move to membrane
• second reaction layer: O2 splits and combines with protons and electrons = water vapor as emission
    * pros: efficient at turning PE to ME than internal combustion engines
    * cons: expensive, production of hydrogen fuel requires some use of nonrenewable resources

6.12 Wind Energy

• KE from moving air → moves turbine → powers generator → generates electricity
    * has grown exponentially in the past 20 years
    * pros: renewable, clean, can use land for multiple uses, can be used on all types of land (ie. mountains, coasts, forests, etc.)
    * cons: limitations on flying (ie. killing birds), required maintenance, location must have consistent wind patterns

6.13 Energy Conservation

• using less energy decreases energy dependence of humans and lessens impact (footprint) on the environment
    * adjusting the thermostat to appropriate temperatures
    * using energy-efficient appliances
      * ex. energy star appliances use significantly less energy
    * use less water
      * taking shorter showers
      * doing large loads of laundry & using the cold cycle
• conservation landscaping: reducing irrigation energy, plant trees to match energy needs
    * ex. using a shade tree, matching your location/climate to compatible plants
• transportation: meeting cafe standards (corporate average fuel economy standards) (using less fuel to go more miles), electric/hybrid vehicles, ridesharing (public transportation/carpooling)
• using green building design elements (ie. solar windows, thermal mass, insulation, lightning from sun, green roof)

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