AP Environmental Science Unit 6

Nonrenewable Energy sources

A source of energy that is a finite supply capable of being exhausted.

Nuclear, coal, oil etc.

renewable energy sources

sources of energy able to be replaced through ongoing natural processes

biomass, hydroelectric, solar, geothermal etc.

Global energy use

is not even between developed and developing countries

most used energy resource is fossil fuels, increasing trend towards renewables

Percentage change formula

Final-initial/initial *100 (always positive/ take absolute value)

as a country develops/ industrializes

need for fossil fuels increase

bike to car to plane use

farm to industrial production

factors that contribute to energy source preference

availability: what fuels can consumers gets easily

price: supply and demand

governmental regulations: subsidy and taxes

wood and charcoal

used in developing countries

easy to access

removal of trees can lead to soil erosion and deforestation.

Peat

decomposed organic material that can be used for fuel and mulch, a precursor to coal.

used in developing countries

using it indoors without proper ventilation can cause air pollution and health problems such as respiratory illnesses

stages of coal

peat, lignite, bituminous, anthracite

lignite

the least pure coal.

low heat capacity and low pressure, low sulfur and high moisture which causes smoke

bituminous coal

The most common form of coal; produces a high amount of heat and is used extensively by electric power plants. high sulfur

Note: Sulfur emissions mix with H2O vapor and cause acid deposition

anthracite

high price, best quality, high heating capacity, low sulfur content

natural gas

cleanest fossil fuel

negligible amount of SO2, mercury and particulates in comparison to coal and oil

mostly methane (CH4)

easily transportable

still produces carbon emissions

process of recovering crude oil from tar sands

not ideal, pumping oil from the ground is easier

removing water, sand and purfiying oil

Fractional distillation

heating up crude oil in refineries to take advantage of the different boiling points of the fuels for creating of differert forms of fuel like gasoline , diesel etc.

Cogeneration

Production of two useful forms of energy, such as high-temperature heat or steam and electricity, from the same fuel source.

more efficient

ex. creating electricity using an engine and using heat created by the engine to heat. w

Oil and Natural Gas Formation

ocean, sand and silt put pressure and heat on small plant and animal remains that eventually turn into oil and natural gas

age of rocks determines what resoures will be available

oil and gas formation happens at the same time

combustion process

Input: fuel and oxygen O2

Output: CO2, CO, H2O

Fuel+ O2 --- CO2+H2O

Producing electricity from coal

1) pulvirizing coal, using small coal

2) burning causes boiling and steam which turns a turbine

3) turning a turbine creates energy with help of a generator

requires water for use and for cooling

potential problems of producing electricity from coal

1) mining causes destruction of habitat

2) pulverized coal is easily flammable and harmful to respitory system

3) heavy use of water can deplete habitat for species

4) carbon dioxide increases greenhouse effect globally

5) impurities in coal such as mercury and sulfur is released into air and water

oil and natural gas extraction

+formed from plants and animal fossils in ocean

+liquid has to be pumped out, much drilling done at sea

+gas is collected through hydraulic fracturing gas found at many levels in rock

-oil extraction- habitat destruction, the potential for spills (leakage)

-gas extraction (hydraulic fracturing)- the destruction of habitat, water contamination, earthquakes

coal mining

+coal has to be dug out

+usability depends on how deep it can be found

+surface mining and subsurface mining methods are used

surface mining- removal of topsoil and habitat, overburden

subsurface mining- destruction of habitat, dangerous for humans

hydraulic fracturing (fracking)

pumping water at high pressure to break apart rocks and thereby release natural gas

hydraulic fracturing (fracking) process

1 well is made

2 pipe is inserted

3 fracking fluid inserted (sent down)

4 gas flows out because rock is fracked

environmental problems caused by fracking

1 well can contaminate water and destroy/harm habitat

2 if the pipe is not lined properly, may contaminate water

3 fracking fluid contains Volatile Organic Compound (VOCs) which may contaminate land, water and mix into the atmosphere

4 natural gas and methane may leak out

5 process may cause earthquakes

6 uses water as a resource

nuclear fission process

1 Uranium-235 placed into fuel rods

2 struck by an outside neutron

3 process of splitting U-235 releases large amounts of heat

4 heat used to generate steam from the water

5 steam turns a turbine

6 turbine powers a generator

7 generator makes electricity

8 steam cools and can be used again, heats get released

pros of nuclear power

1 low gas emissions

2 high power output

3 low cost (after initial construction)

4 no mining for fossil fuels

5 no primary/secondary air pollutants

cons of nuclear power

1 long-lived hazardous waste/nuclear accidents

2 thermal pollution

3 very high initial cost (billions)

4 mining for construction and uranium

5 nonrenewable resource

nuclear waste

spent Uranium-235 remains inactive

+U-235 breaks down and can't create heat as much

+This spent Uranium gathers neutrons

+becomes heavier - like plutonium

+ remains radioactive for up to 24,000 years (10 half lives)

issues with nuclear waste

+due to long lived waste, strorage is hard

+storage happens on site, burried deeply

+federal site commissioned at Yucca Mountain, Nevade (not currently used, people of Nevada opposed it)

+many sites means more chances of radioactive waste leaking into environment (eg. water)

Nuclear Power Accidents

Three Mile Island, Pennsylvania USA- 1979

Chernobyl, Ukraine - 1986

Fukushima, Japan - 2011

causes can be natural or human caused (mechanical)

Three Mile Island incident

the accident started in a non-nuclear portion of reactor:

1 water pump failed to allow water in

2 reactor never cooled down

3 fuel began to meltdown partially

4 no explosion or long-term high radiation exposure

Chernobly incident

accident arose from a safety test:

1 power turned off during simulation

2 extra power from turbine was supposed to keep reactor power up enough to cool

3 when test completed, control rods did not drop

4 explosion occured, releasing most radiation ever from an accident

Fukushima Incident

the accident caused by a natural disaster:

1 earthquake and tsunami occured in pacific

2 earthquake caused an emergency shut down

3 tsunami wave flooded 4 reactors

4 three nuclear reactors melted down at the same time

5 accident was deemed preventable

half-life of radioactive material

+ half life is a measure of time for half of an atomic nucleus to decay

+ decays into another atom, emitting radiation

+ ten half-lives generally means safety

biomass as a source of energy

+energy stored from phosynthesis

+biomass is the leading renewable energy source worldwide

+burning biomass is a direct source of heat for many in devaloping nations

+examples of biomass used as heat sources:

wood, peat, charcoal, crop residue, manure

positive consequences of biomass use for energy

+easily accessible

+relatively inexpensive

+ used for heating and cooking

negative consequences of biomass use for energy

+releases air pollutants (carbon dioxide, carbon monoxide, particulates, and volatile organic compounds)

+typically burned indoors, intensifying health effects of pollutants

+overharvesting of trees for fuelwood results in deforestation

Biofuels

Fuels, such as ethanol or methanol, that are created from the fermentation of plants or plant products.

Ethanol

made by fermenting plant-based starches into sugars and eventually alcohol

+typically mixed with gasoline to create gasohol (90% gas, 10% ethanol)

+E-85 and flex-fuel vehicles can run on a mixture of 85% ethanol, 15% gas

Biodiesel

vegetable oil that can be used to run a car

+extraced and chemically modified oil from plants

+can be a direct substitute for diesel fuel

sources for biofuels

Ethanol

+corn (US)

+sugarcane (Brazil)

+sugar beets (US and Brazil)

Biodiesel

+soybeans (Brazil and US)

+oil palms (southeast asia)

+rapeseed (Europe)

pros of using biofuels

+combustion is carbon neutral (produces modern carbon which is already in the atmosphere)

+potentially renewable

+can be produces domestically (for US)

cons of using biofuels

+net energy is low (more gasohol is needed to go to the same distance

+harvesting of crops for ethanol has the potential for

increased use of fossil fuels in harvest

increased deforestation

reduction in fertility of agricultural land

more sustainable solutions being researched

Ethanol:

switchgrass (grass that can be harvested over and over year after year)

biodiesel:

SVO (straight Vegetable Oil) using oil used in restaurants to power vehicles

Algea

photovoltaic solar cells

A system of capturing energy from sunlight and converting it directly into electricity

energy from the sunlight releases electrons, the flow of electrons creates electricity

pros and cons of photovoltaics

pros

+generation of electricity

+can reduce habitat destruction depending on installation placement (can be placed on the roof of apartments)

+lange and small scale applications

cons

-use is limited by the availability of sunlight

-limited lifespan of nonrenewable PV cells

-expensive

-solar farms may negatively impact fragile desert ecosystems

active solar (concentrated solar power)

a liquid is being heated up by concentrated solar beams, surfaces reflecting the solar beams, liquid is heating the water, water is creating steam that will turn turbine and charging a generator

aside from electricity, heat is also produces with active solar system

pros and cons of active solar

pros

+generates electricity and heat

+large and small scale application

cons

-expensive

-requires maintenance

-solar farms may negatively impact fragile desert ecosystems

-solar farms require high solar intensity to maximize efficiency

Passive solar

A system that uses the sun's energy without requiring mechanical devices (pumps or fans) to distribute the collected heat. House has to face south. Keeping sunlight out during summers and in during winters

requires good insulation

pros and cons of passive solar

pros

+relatively inexpensive and low maintenance

cons

-some aspects are difficult to implement retroactively

-energy cannot be collected or stored

hydroelectricity from dams and reservoirs

as water comes from the gates (intake) has a kinetic energy that spins the turbine, turbine turns the generator and thus creates electricity

micro-hydropower

electricity produced in a small stream without having to build a big dam

tidal power

Energy generated by ocean tides in places where favorable topography allows for construction of a power plant.

waves helps creation of electricity

pros of hydroelectric power

+no air pollution

+no waste

+relatiively inexpensive electric generation

+additional services provided by the reservoir (recreational service, fishery, extra water for irrigation)

cons of hydroelectric power

-flooding of land for the reservoir

-disruption to flow rates of river

-high maintenance cost for tidal (saltwater harming machinery and steel)

-high construction cost for dams

-most viable sites are already used

geothermal energy process

1 water is pumped down an injection well

2 stored heat from the Earth's interior turns the water into steam

3 steam rises from the production well

4 kinetic energy of the steam turns a turbine

5 turbine turns a generator

6 generator producess electricity

pros of geothermal energy

+no combustion, no CO2 emissions,

+not dependent on variable weather factors, like solar and wind

cons of geothermal energy

-accessibility at reasonable cost is limited

-release of gases during drilling and processing (hyrogen sulfide gas)

-short term depletion of heat possible

-impact on groundwater

home heating with geothermal

1 fluid pumped down to earth

2 fluid heats because land cools slower

hydrogen fuel cell, process

1 Hydrogen fuel (H2) added to cell splits into protons (H+) and electrons (-) in the first reaction layer

2 protons and electrons take different paths,

-protons move across the membrane

-electrons are free to take an alternate route, creating a flow of electric current

3 in the second reaction layer, oxygen molecules (O2) are split and combine with protons and electrons

-Water vapor is the only emission from the fuel cell

hydrogen fuel cell

a cell that generates electricity from a controlled reaction between hydrogen and oxygen

water is the only emission and byproduct

source of hydrogen fuel

+hydrogen can come from water

electrolysis- electric current used to split water into hydrogen and oxygen

decreases net energy of fuel cell because energy is used for creating the energy

+can come from natural gas

splitting methane (CH4) using heat-results in CO2 pollution

hydrogen fuel cell technology

it is expensive because...

1 it is a new technology with research and devalopment costs

2 scale of technology is low

3 raw materials are rate and expensive (platinium and other rare earth minerals are used as catalysts)

pros and cons of hydrogen fuel cells

pros

+no CO2 emissions (if produced from water)

+electricity is more efficient than internal combustion

cons

-technology is expensive

-producing hydrogen fuel from fossil fuel is not clean

producing wind energy

1 kinetic energy from moving air cought in turbine

2 kinetic energy from the turbine turns the generator inside the windmill

3 generator produces electricity

Pros and cons of wind energy

pros

+renewable

+clean

+allows for multiple use of lands

cons

-birds abd bats can be killed by turbines

-maintanance is required

-locations must have consistent winds to provide consistent power supply (need backup power on days that are not windy)

energy conservation

the practice of finding ways to use less energy or to use energy more efficiently.

It is important because every energy source has its downsides.

energy conservation at home

+adjust the thermostat (petek)

+use energy-efficient appliances

+conserve water with shorter showers and doing larger laundry

+reduce irrigation energy

+planting trees to match energy needs (gölge oluşturma, sıcaklık stabil tutma, rüzgar kesme)

energy conservation in transportation

+fuel economy standards (CAFE)

+Battery electric vehichles and hybrids are more efficient than the internal combustion engine and their energy can be renewably sourced

+carpooling

+public transportation

corporate Avarage Fuel Economy Standards (CAFE)

mandates level of fuel efficiency that corporates and cars need to hit to operate in US

energy conservation in building design

passive

+passive solar windowns

+thermal mass

+insulation

+lightining from the sun

+green roof (with trees)

active

+geothermal or solar heating systems

+solar panels