6.3 Fuel Types and Uses, 6.5 Fossil Fuels

Sources of biomass

forestry crops and residues, agricultural crops and residues, sewage, industrial residues, animal residues, and municipal solid waste

coal formation

pressure from overlying rock and sediment layers compact peat into coal over time

order of energy density and quality

(L) lignite > bituminous > anthracite (M)

anthracite

the most valuable form of coal (highest quality)

natural gas

decaying remains of plants and animals (mostly marine life) are buried under layers of rock and converted by pressure into oil (petroleum) and natural gas over time

what is natural gas mainly made of and found?

Mostly made of methane (CH4) and found on top of trapped oil (petroleum) deposits

“Cleanest’ fossil fuel

natural gas (produces the fewest air pollutants and least CO2 when burned)

crude oil

decaying organic matter trapped under rock layers is compressed into oil over time

how is crude oil extracted

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

where can crude oil also be found

from tar sands (combo of clay, sand, water, and bitumen)

bitumen

thick, sticky, semi-solid form of petroleum (not liquid)

tar sand

extremely energy and water intensive; lots of water needed to be heated to create steam that’s piped down into the tar sand to melt the bitumen into liquid that can flow up a pipe, lots more water used to separate oil from impurities (sand, clay) at the refinery

fractional distillation

components in a chemical mixture are separated into different parts (called fractions) according to their different boiling points

fossil fuel combustion

reaction between oxygen and fossil fuels that releases energy as heat and produces CO2 and H20 as products

hydroCARBONS

burned to release energy and the carbon stored in them reacts with O2 in the air to form CO2

number 1 source of electricity production globally

coal, followed by natural gas

typical generating plants

1. resource is mined, refined, and transported

2. resource combusted in boiler'/furnace

3. kinetic energy transferred to liquid water > steam

4. steam spins turbine

5. turbine generator produces electricity

environmental consequences of coal

habitat destruction, produces pollutants and releases CO2 (GHG > Global warming) (PM, toxic ash, SOx and NOx)

Cogeneration

when heat produced from electricity generation is used to provide heat (air and hot water) to a building

CHP (Combined heat and power) systems

are close to 90% efficient (much better than coal/NG alone)

oil/petroleum extraction

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

environmental consequences of tar sands

habitat destruction, ground or nearby surface water depletion

environmental consequences of crude oil/petroleum

possibility of spill (either from tanker ships or pipelines breaking), habitat loss or fragmentation when land is cleared for roads, drilling equipment, pipelines

environmental consequences of fracking

possibility of well leaking and contaminating groundwater with fracking fluid, depletion of ground or surface waters nearby (as they’re drawn from for fracking fluid), habitat loss, CH4 methane (GHG) releas