APES unit 6 (energy resources and consumption)

renewable energy sources

can be replenished naturally, at or near the rate of consumption, and reused

depletable renewables

can run out if overused (ex: wood)

nondepletable renewables

don't run out if overused (ex: solar)

non renewable energy source

exist in fixed amounts on earth and can't be easily replaced or regenerated (ex: fossil fuels and nuclear)

rate of consumption for renewable energy

rate of use must be at or below rate of regeneration for renewables

energy use based on development of countries

developed countries use more energy per capita than less developed countries but less energy overall

most common fuel sources globally

1. fossil fuels 2. hydroelectric 3. nuclear

subsistence fuels

biomass that are easily gathered or purchased (ex: wood, charcoal)

as developing countries develop, fossil fuel consumption will ________

increase

effect of availability on ff use

ff uses depends on discovered reserves and accessibility of these reserves

effect of price on ff use

ff prices fluctuate dramatically with discovery of new reserves of depletion of existing ones

effect of government regulation on energy use

the government can mandate certain energy sources mixes (25% renewable by 2025)

things the government can do to impact energy use

taxes, rebates, tax credits

peat

partially decomposed organic matter found in wet, acidic ecosystems like bogs and moors; when dried can be used as (subsistence) fuel

coal formation

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

types of coal

lignite, bituminous, anthracite

higher density in coal means ________

more energy when burned (anthracite is most dense)

natural gas

decaying remains of plants and animals are buried under layers of rock and converted by pressure into oil and natural gas over time

what is the biggest part of natural gas

methane (CH4)

"cleanest' ff

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

crude oil (petroleum)

formed the same way as natural gas but it turns into crude oil

how is crude oil extracted

drilling, tar sands

tar sands

combination of clay, sand, water and bitumen

bitumen

thinck, sticky, semi-solid for of petroleum

how is crude oil separated

fractional distillation

fractional distillation process

crude oil is burned in a furnace and vapor passes into a column where different hydrocarbons are separated based on their boiling points

ff energy reserves

coal (~100-150 years), natural gas (~50-60 years), oil (~50 years)

fracking

method of natural gas extraction that has extended access to natural gas

fracking increases and extends ________

supply of natural gas

world's largest tar sands reserve

canada (alberta region)

types of ffs

methane, gasoline, propane, butane, and coal

ff to generate electricity steps

heat turns water into steam, steam turns a turbine, turbine powers generator, generator produces electricity

environmental consequences of coal

habitat destruction to clear land for mining; produces pollutants and releases CO2 (global warming)

efficiency of generating electricity

much of the energy is not converted into electricity, and instead escapes as heat

cogeneration

when the heat produced from electricity generation is used to provide heat to a building

CHP

combine heat and power

environmental consequences of tar sands

habitat destruction to clear land; ground or nearby surface water depletion; water contamination

environmental consequences of crude oil/petroleum

possibility of spill; habitat loss or fragmentation when land is cleared

environmental consequences of fracking

possibility of well leaking and contamination groundwater; depletion of ground or surface waters nearby

nuclear fission and radioactivity

a neutron is fired into the nucleus of a radioactive (unstable) element; nucleus breaks apart and releases lots of energy and more neutrons that break more nuclei apart, releasing more energy

radioactivity

the energy given off by the nucleus of a radioactive isotope (uranium-235)

radioactive half-life

the amount of time it takes for 50% of radioactive substance to decay

generating electricity through nuclear fission

same electricity generation process as with ffs, just uranium fission to heat water into steam; U-235 stored in fuel rods, submerged in water in reaction core, heat from fission turns H2O into steam

control rods for nuclear fission

lowered into reactor core to absorb neutrons and slow down the reaction, preventing meltdown (explosion)

water pump for nuclear fission

brings in cool water to be turned into steam and also cools reactor down from overheating

cooling tower for nuclear fission

allows steam from the turbine to condense back into liquid and cool down before being reused

nuclear energy is ________ because radioactive elements like uranium are ________

non-renewable; limited

negatives to nuclear energy

possibility of meltdown; radioactive contamination (spent fuel rods, mine tailings); water use; thermal pollution

spent fuel rods

used fuel rods remain radioactive for millions of years and need to be stored in lead containers on site at nuclear power plants

mine tailings

leftover rock and soil from mining may have radioactive elements that can contaminate water or soil nearby

water use for nuclear energy

nuclear power plants require lots of water and can deplete local surface of groundwater sources

thermal pollution from nuclear energy

hot water from power plant released back into surface waters can cause thermal pollution (decreased O2 and suffocation)

famous nuclear meltdowns

three mile island (usa), fukushima (japan), and chernobyl (ukraine)

three mile island (usa) meltdown

partial meltdown due to testing error; radiation released but no deaths or residual cancer cases

fukushima (japan) meltdown

an earthquake and tsunami triggered cooling pup failure that lead to a meltdown and widespread radiation release

chernobyl (ukraine) meltdown

stuck cooling valve during test lead to complete meltdown, several deaths, and widespread radiation release

environmental consequences of meltdown

genetic mutation and cancer in surrounding people, animals and plants due to radiation released from reactor core; contaminated soil; radiation spread

contaminated soil from nuclear meltdown

radiation can remain in soil and harm plants and animals in the future (genetic mutations)

radiation spread from nuclear meltdown

radiation can be carried by the wind over long distances, affecting ecosystems far from the meltdown site

biomass

organic matter (wood, dried animal waste, dead leaves, etc.) burned to release heat

biofuels

liquid fuels (ethanol, biodiesel) created from biomass (corn, sugar cane, palm oil)

biomass burning releases _________, but doesn't increase atmospheric ________ levels like ff burning does

CO2

modern carbon

CO2 that was recently sequestered, or taken out of the atmosphere

fossil carbon

carbon that has be stored for millions of years

biomass burning is considered ________

carbon neutral

biomas releases ________

CO, NOx, PM, and VOCs (all respiratory irritants)

environmental consequences of biomass burning

deforestation and air pollutants

how are biofuels made

corn and sugarcane are fermented into ethanol which is mixed with gasoline

environmental consequences of biofuels

all the negative consequences of monocropping (erosion, habitat loss, GHG)

biodiesel

liquid fuels produced specifically from plant oils (soy, canola, palm)

environmental consequences of biodiesel

CO2 release, loss of habitat, soil erosion, loss of air filtration, more GHGs than ff

passive solar energy

absorbing or blocking heat from sun, without the use of mechanical/electrical equipment

active solar energy

use of mechanical/electrical equipment to capture sun's heat, or convert light rays directly into electricity

photovoltaic cells (PV)

aka 'solar panels'; contain semiconductor that emits low voltage electrical current when exposed to sun

drawback to solar panels

intermittency (solar energy can only be generated during the day)

concentrated solar thermal (CST)

mirrors reflect sun's rays onto a central water tower in order to heat water to produce steam to turn a turbine

drawback to CST

habitat destruction and light beams frying birds in mid air

community (solar farm)

large-scale 'farms' can generate lots of electricity, bu take up land and cause habitat loss/fragmentation

rooftop solar

rooftop solar doesn't take up land, but only produces a little electricity

FRQ tip about solar energy

don't just say 'solar panels'; differentiate between rooftop solar or large scale solar 'farms'

pros of solar energy

no air pollutants released to generate electricity; no CO2 released when generating electricity; renewable; no mining of ffs for electricity production

cons of solar energy

semiconductor metals (silicon) still need to be mined to produce PV cells, which can disrupt habitats and pollute water with mine tailings, and the air with PM; silicon is a limited resource; solar panel farms can displace habitats

hydroelectricity

kinetic energy of moving water spins a turbine and powers a generator

largest renewable source of electricity globally

hydroelectricity

water impoundment (dams)

dam built in a river creates a large artificial lake behind the dam (reservoir)

two big impacts of dams

flooding of ecosystems behind dam; sedimentation (buildup of sediments behind dam)

run of river system

a dam diverts the natural current of a river through a man-made channel beside the river

tidal power

comes from tidal ocean flow turning turbine (coastal areas only)

ecological drawbacks of hydro dams

reservoir floods habitats behind dam (forests/wetlands gone; river becomes a lake)

environmental drawbacks of hydro dams

ff combustion during combustion during dam construction; increased evap. due to larger surface area or reservoir; methane release due to anaerobic decomp. of organic matter in reservoir

economic drawbacks of hydro dams

human homes and businesses must be relocated due to reservoir flooding; initial construction is very expensive; sediment buildup must be dredged eventually

fish ladders

cement 'steps' or series of pools that migratory fish like salmon can use to continue migration upstream, around or over dams

benefits of hydro dams

non GHG emissions when producing electricity; jobs are created to build and maintain the dam; allows for control of downstream seasonal flooding

geothermal basics

natural radioactive decay of elements deep in earth's core gives off heat, driving magma convection currents which carry heat to the upper portion of mantle, close to earth's surface

geothermal for electricity

naturally heated water reservoirs underground are drilled into & piped up to the surface (or water can be piped down into naturally heated rock layers

ground source heat pump

around 10 ft down, the ground stores heat from the sun and heat absorbing fluid is pumped through a pipe to there, either heating or cooling a house

geothermal heating

piping water deep into ground (kms) to be heated by magma and then transferring heat from water to the building

pros of geothermal

potentially renewable (only if water is piped back into the ground for reuse); much less CO2 emissions; no release of PM, SOx, NOx, or CO

cons of geothermal

not everywhere in the earth has access; hydrogen sulfide can be released (very toxic to humans and animals); cost of drilling can be really high

hydrogen fuel cell

using hydrogen as a renewable, alternative fuel source to ffs