6.5 Fossil Fuels

Flowback water

(used fracking fluid) flows back out well & is collected and stored in containers or ponds nearby

Environmental Consequences: Coal

- Habitat destruction to clear land for mining - Produces pollutants & releases CO2 (GHG → global warming) - Releases more CO2 than any other FF when burned for electricity gen. - Releases PM (soot, ash) which can irritate respiratory tracts of humans/animals - Produces toxic ash contaminated with lead, mercury, and arsenic - Taken to landfills or stored in ash ponds; both can leak into ground/surface waters, or into soil - Releases SOx & NOx (sulfur and nitrogen oxides) which irritate resp. systems, and contribute to smog and acid precipitation

Environmental Consequences: Tar Sands

- Habitat destruction to clear land for: roads, drilling equipment, digging through ground surface to reach deposits (biodiv. loss) - Ground or nearby surface water depletion (H2O needed for steam & for washing impurities from bitumen at refinery) - Water contamination: tailing ponds (holes dug for storing wastewater) can overflow & run into nearby surface waters, or leach into groundwater - Benzene (carcinogen) salts, acids, hydrocarbons, bitumen - All toxic to plant and animals - CO2 released by machinery during extraction, transport, refinement

Fracking (Hydraulic Fracturing) - How used

-Used to extract natural gas from sedimentary rock -Vertical well is drilled down to sed. rock layer, then turns horizontally into the rock layer -Perforating gun cracks (fractures) the rock layer around hor. well, making it more permeable -Fracking fluid (water, salt, detergents, acids) is pumped into well @ very high pressure to crack the rock even more & allow natural gas to flow out -Nat. gas is collected @ surface & shipped for processing/use

How efficient is coal as a fuel source

●Coal is ~30% efficient as a fuel source for generating electricity (30% of energy from the bonds in the hydrocarbons are converted to electricity) ○Nat. Gas is ~60% efficient when it's burned to generate electricity ⛰️ Much of the energy "lost" or not converted into electricity escapes as heat Cogeneration: when the heat produced from electricity generation is used to provide heat (air & hot water) to a building; CHP (Combined Heat and Power) systems are close to 90% efficient (much better than coal/NG alone)

Fossil Fuel Combustion - Products

●Reaction between Oxygen (O2) & fossil fuels (hydrocarbons) that releases energy as heat and produces CO2 & H2O as products ⛰️ Methane (natural gas), gasoline, propane, butane, coal are all fossil fuels (hydrocarbons) that release energy in the same way way Wood and biomass work the same, carbon is burned & reacts with O2 to form CO2 & give off energy

Environmental Consequences: Crude Oil/Petroleum

- Possibility of spill (either from tanker ships or pipelines breaking - Spills in water = crude oil covering sun, clogging fish gills, suffocating many ocean animals, sticking to bird feathers - Spills on land = toxic to plant roots, surface or groundwater contamination (with hydrocarbons/crude oil) - Habitat loss or fragmentation when land is cleared for roads, drilling equipment, pipelines

Environmental Consequences: Fracking

- Possibility of well leaking & contaminating groundwater with fracking fluid (salt, detergents, acids) or hydrocarbons ●Ponds can overflow or leach into ground & contaminate surface or ground waters with fracking fluid (salt, detergents, acids) ●Can be toxic to plants & animals that rely on these water sources - Depletion of ground or surface waters nearby (as they're drawn from for fracking fluid) ●Increased seismic activity (earthquakes) linked with wastewater injection wells (storing fracking fluid deep underground) - HAB LOSS AND CH4 RELEASE

Describe the use and methods of fossil fuels in power generation.

- The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy. - Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which generates electricity. - Humans use a variety of methods to extract fossil fuels from the earth for energy generation.

Explain one environmental consequence of tar sands petroleum extraction. Explain a different environmental consequence of hydraulic fracturing.

6.5

Oil/Petroleum Extraction

Extracted by drilling a well through the overlying rock layers to reach the underground deposit and then pumping liquid oil out under pressure

Describe the effects of fossil fuels on the environment.

Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds

Combustion is

Remember: Combustion is a step in the CARBON cycle: hydroCARBONS (FFs) are burned to release energy & the carbon stored in them reacts with O2 in the air to form CO2

Steps to produce initial heat...

These steps of electricity gen. are the same, no matter what you're burning to produce the initial heat Heat →Water into Steam → Steam turns a turbine → Turbine powers generator → Generator produces electricity ⛰️ Coal, oil, natural gas, biomass, and trash can all be burned to drive this same process and create energy. Even nuclear energy work similarly, with nuclear fission producing the initial heat