AP Environmental Science unit 6

Nonrenewable Energy

Exist in a fixed amount: cannot be replaced on a human time scale

Renewable Energy

Can be replenished naturally, at or near the rate of consumption

types of nonrenewable energy sources

Oil, Coal, Natural gas and Nuclear

Types of renewable energy sources

Solar, wind, biomass, geothermal, hydropower

Commercial energy sources

they are bought and sold (oil, coal, natural gas)

Subsistence energy sources

They are gathered by individuals for their own immediate needs (straw, sticks, animal dung)

midwest/SE energy use

Coal for electricity

West/NE

nuclear/natural gas/hydroelectric

peat

partially decomposed organic material that can be burned for fuel

benefits of hydroelecti

pathway of energy

1. Energy resource 2. Extraction 3. Transportation 4. processing 5. Combustion/energy conversion 6a. disposal/ transportation of waste 6b. Electricity generation 7. electricity transmission 8. User

EROEI

Energy return on Energy Investment (Output/input)

secondary energy source

converted from a primary source

Energy carrier

can move and deliver energy in a conveniently usable form

Electrical grad

network of interconnected transmission lines that connect power plants together and link them with end users

Capacity factor

the fraction of time power plant operates in a year

cogeneration

combined heat and power

fossil fuels

derived from biological material that fossilized millions of years ago, anaerobic condition , nonrenewable

fossil fuel combustion

oxygen combines with a hydrocarbon to form water and carbon dioxide and produces heat

Incomplete combustion

not enough 02 present so leftover carbon is getting released as soot and CO2

Coal

the most abundant and dirty of the fossil fuels

advantages of coal

abundant, ease of extraction through surface mining, safe storage for future needs, Ease of transportation, Needs little refining

Disadvantages of coal

surface mining, Air pollution, residual ash

petroleum

cleaner than coal, a fluid mixture of hydrocarbons, water, and sulfur, Mobile combustion applications, less dense, pipelines and supertankers

crude oil

liquid petroleum removed from ground

oil refining

complex and dangerous; requires significant $$$ investment

advantages of oil

liquids are convenient to transport and use, compared to coal, energy dense and cleaner-burning

disadvantages of oil

toxins released into the atmosphere, Potential for leakage and spills, habitat destruction, gas flares

Exxon Valdez oil spill

supertanker crashed into a reef in Prince William Sound, AK, half a million birds and thousands of marine mammals killed

ANWR

exploration might yield up to 1.4 trillion L of oil and natural gas

Deep Water Horizon

explosion at a BP oil rig in the Gulf of Mexico, released 780 million L

Natural Gas

the cleanest of the 3 fossil fuels, lighter than oil

uses of Natural Gas

industrial processes, Electricity generation, Residential heating

Advantages of Natural Gas

Fewer impurities, Emits 60% the CO2 of coal, Convenient through pipeline delivery

disadvantages of Natural gas

Escaped Natural gas a potent greenhouse gas, hydraulic fracturing

Energy intensity

Energy use per unit of GDP

Nuclear Fission

Neutron strikes a large atomic nucleus, releases more neutrons and heat energy, additional neutrons release more energy in a chain reaction

Nuclear Power plant

Uses heat energy to produce steam

fuel rods

tubes that contain the uranium pellets

control rods

inserted between fuel rods to absorb excess neutrons and prevent meltdowns and fires

meltdown

fuel rods become too hot and melt; water boils away; radioactivity released

advantages of Nuclear Energy

no emissions, large scale energy production, predictability of energy source

disadvantages of Nuclear Energy

Nuclear accidents, radioactive waste disposal

radioactive waste

high-level: used fuel rods. Low-level: contaminated clothing. Uranium mine trailing

half-life

the time it takes for half of a substance to radioactively decay (A=A0(1/2)^t/n)

Biomass

wood, charcoal, animal products, plant remains, solid waste, biofuels

Passive solar heating

south-facing windows, dark roofs, solar ovens

active solar technologies

solar water heating, photovoltaic, Concentrating solar thermal electricity generation

benefits of solar energy

no emission, can produce electricity during peak demand, Economically feasible

drawbacks of solar energy

expensive, payback takes longer, requires energy and water and can release toxic metals and chemical

photovoltaic cells

the sunlights energy activated and releases electrons from thin layers of semiconducting material, generates a low-voltage electric current

hydroelectricity

power generated by kinetic energy of moving water

methods of generating hydroelectricity

run-of-the-river, water impoundment (dams), tidal systems

benefits of hydroelectricity

water for year around irrigation, drinking water, recreation, and fishing in reservoirs, hydropower is cheap and reduces downstream flooding

drawbacks of hydroelectricity

Newly flooded land destroys cropland, and forests and displaced people, water loss due to evaporation, downstream land deprived of nutrients, and risk of catastrophic flooding

Geothermal energy

heat comes from the natural radioactive decay of elements deep within earth, convection currents brings magma towards the crust and heat groundwater

hydrogen fuel cell

operate like a battery, but reactants are added continuously (2H2O +O2 → Energy +2H2O)

benefits of hydrogen fuel cells

No emissions, 80% efficient

drawbacks of hydrogen fuel cells

Obtain hydrogen, distribution network, fire and explosions

benefits of wind energy

Nondxpletable, free and clean, wind farms and share land with other uses

drawbacks of wind farms

batteries for storage are expensive and hard to recycle, the unpredictability of wind, bird and bat collisions, noise and aesthetic issues

conservation

use less energy

energy efficiency

do same work for less amount of energy

passive solar design

uses solar radiation to maintain indoor temperature