APES Unit 6: Energy Sources and Their Environmental Impact

Renewable energy source

can be replenished naturally at or near the rate of consumption

Depletable renewable energy

can run out if over used

Nondepletable renewable energy

do not run out if overused (ex: solar, wind, etc.)

Nonrenewable energy sources

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

Rate of consumption

we must be at or below the rate of regeneration for renewables.

Developed vs. undeveloped countries

developed nations use much more energy.

Fossil Fuels

fossil fuels are by far the most common fuel source globally.

Increasing development increases fossil fuels

as we develop globally we will use much more fossil fuels. (the more wealthy countries become the more energy they demand)

Factors that affect energy source use

Availability, Prices, Government Regulation

Availability

fossil fuel use depend on the accessibility of these reserves

Prices

fossil fuel prices fluctuate dramatically with discovery of more, or less in the reserve

Government Regulation

governments can mandate certain sources of energy.

Subsistence Fuels

biomass fuel sources that are easily accessible (ex: woods, charcoal and peat)

Coal Formation

Pressure from overlying rock layer compacts peat into coal over time

Energy density and quality of coal

In order of energy density and quality: lignite, bituminous, anthracite

Anthracite

is the most valuable and wanted type of coal

Natural Gas

formed from decaying remains of plants and animals that are buried under layers of rock and converted by pressure into oils and natural gas over time.

Natural gas composition

is mostly methane and is found on top of trapped petroleum deposits

Cleanest fossil fuel

Natural gas is considered the cleanest fossil fuel

True Oil/Petroleum

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

Extraction of oil

Extracted by drilling a well through overlying rock layers to reach the underground deposits

Fossil Fuel Products

petroleum is converted into lots of different products through fractional distillation.

Fractional Distillation

separation of a liquid mixture into fractions differing in boiling point by means of distillation, typically using a fractionating column.

Fossil Fuel Reserves

Coal - main deposit is in the US, Natural Gas - main deposit in Russia, Oil - main deposit in Venezuela

Fracking

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

Bitumen

THICK and dense crude oil that is hard to extract

Fossil Fuel Combustion

reaction between oxygen and fossil files that releases energy as heat.

Generating Electricity

coal is only about 30% efficient, natural gas is 60%.

Cogeneration

We can limit the energy loss in electricity generation by using cogeneration.

Cogeneration

When heat produced from electricity generation is used to provide heat to a building.

Environmental Consequences of Tar Sands

Habitat destruction, contamination of ground and surface waters, depletion of ground and surface water, and release of carbon dioxide.

Environmental Consequences of crude oil/petroleum

Possibility of a spill and habitat destruction or fragmentation.

Fracking

Used to extract natural gas from sedimentary rocks.

Steps of Fracking

Vertical well is drilled down to the rock then turns horizontally into the rock layer; perforating gun cracks the rock layer around the well making it permeable; fracking fluid is pumped into the well at very high pressure to crack the rock and allow natural gas to flow out.

Environmental Consequences of Fracking

Possibility of a well leak (containing the used fracking fluid), depletion of groundwater or surface water, increased earthquakes (seismic activity), habitat destruction or fragmentation, and greenhouse gas release.

Nuclear Energy

Energy generated through nuclear fission and radioactivity.

Nuclear Fission

A neutron is fired into the nucleus of a radioactive element such as uranium, causing the nucleus to break apart and release energy and more neutrons.

Radioactivity

The energy given off by the nucleus of a radioactive isotope.

Half Life

The amount of time it takes for 50% of a radioactive substance to decay.

Generating Electricity from Nuclear Energy

Same electricity generation process as with Fossil Fuels just uranium fission to heat water into steam.

Safety in Nuclear Energy

Control rods are lowered into the reactor core to absorb neutrons and slow down reactions; water pump brings in cool water to be turned into steam, preventing overheating; cooling tower allows steam from the turbine to condense back into liquid and then cool.

Nonrenewable Energy

Because we can run out of uranium.

Cleaner Energy

There are no air pollutants released when generating energy.

Drawbacks of Nuclear Energy

Spent fuel rods, possibility of a meltdown, requires lots of water.

Nuclear Meltdowns

Three Mile Island - partial meltdown; Fukushima - full meltdown; Chernobyl - full meltdown.

Consequences of Nuclear Meltdowns

Genetic mutations, cancer in surrounding people and animals, contamination of soil, the spread of radiation (wind can disperse radioactive particles).

Biomass

Organic matter that is burned to release heat, primarily used in developing countries.

Biofuels

Liquid fuels created from biomass (corn, sugar cane or palm oil).

Biomass Burning

Releases carbon dioxide but does not increase atmospheric carbon levels like fossil fuels burning does.

Human Health Consequences of Burning Biomass

Biomass releases many respiratory irritants.

Environmental Consequences of Burning Biomass

Deforestation and air pollutants, habitat loss, soil erosion.

Environmental Consequences of Biofuels

All of the consequences of agricultural practices.

Human Impact of Biofuels

Because it requires so much corn, it can raise corn prices.

Biodiesel

Liquid fuels produced specifically from plant oils, popularly from palm oil.

Passive Solar

Absorb or block heat from the sun without the use of mechanical equipment.

Active solar

use of mechanical or electrical equipment to capture the sun's energy

Photovoltaic Cells

(solar panels), photons cause separation of chargers between two semiconductor layers, electrons separate from the protons and flow through the circuit to then deliver energy.

Drawbacks of solar panels

solar energy can only be captured during the day, hard to store.

Concentrated Solar Thermal

mirrors that reflect the sun's rays onto a central water tower in order to heat water and produce steam to turn turbines that then produce electricity.

Drawbacks of concentrated solar panels

habitat destruction, birds can be hit or hit by the towers in mid air.

Community vs. rooftop solar

community (solar farm), produce lots of electricity. Rooftop solar, won't bring in as much energy but results in less habitat loss.

Solar Energy Pros

no air pollutants, renewable source of energy, no use of fossil fuels.

Solar Energy Cons

can disrupt habitats and pollute water, silicon is limited.

Hydroelectric

the movement of water to generate electricity.

Water Impoundment

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

Drawbacks of hydroelectricity

reservoirs can flood, habitat loss, sediment buildup and other problems.

Fish ladders

steps to series of pools so that migratory species can continue upstream around or over the dams. (solution for salmon migratory problems)

Benefits of hydroelectricity

no air pollutants released when energy is produced, reliable, cultural services, control of seasonal flooding.

River systems

a dam diverts the natural current of a river through man made channels besides the river, bringing it to make energy.

Tidal Energy

comes from the tidal ocean flow turning turbines (in coastal areas ONLY).

Geothermal energy

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

Ground source heat pump

is not geothermal energy - heat absorbing fluid is piped into the ground and is then able to collect it to heat your house in the winter or pull it away to cool your house in the summer.

Geothermal heating

pipe water very far into the ground that is then transferred into the building to heat it.

Pros of geothermal energy

potentially renewable energy, far less fossil fuel emissions.

Cons of geothermal energy

not available everywhere, hydrogen sulfide can be released (lethal), VERY expensive.

Hydrogen fuel cell

most common in vehicles, can possibly replace fossil fuels.

Input of hydrogen fuel cell

Input hydrogen and oxygen but the only output is water (given off as waste product).

Getting hydrogen

splitting water to get the hydrogen, and steam reforming to separating hydrogen.

Pros of hydrogen

can be stored very easily, and transported easily.

Drawbacks of fuel cells

carbon dioxide released when getting the hydrogen, hard to distribute due to gas efficiency, we would need to make the fuel tanks on cars larger.

Wind energy

kinetic energy of wind spins a turbine, which then converts the mechanical energy into electricity.

Average wind turbine capacity

The average turbine can support 460 homes.

Wind turbine locations

clustered in groups in flat open areas. Can be located in agriculture. Offshore wind farms in lakes or oceans = capitalizes on faster wind speeds.

Benefits of wind energy

non depletable, no greenhouse gas emissions, can share land use.

Drawbacks of wind energy

isn't always available, can kill birds, noise pollution.

Small scale energy conservation

lowering thermostat use, conserving water with plants, energy efficient appliances.

Large scale energy conservation

improve fuel economy, give money to electric vehicles to make them cheaper, invest in public transportation.

Sustainable Home Design

ways to either block out or take advantage of the sun's natural heat and keep it for cooling or heating.

Water Conservation

removing turf of grass and replacing it with natural plants, low flow water in toilets and showers, rain barrels.

Transportation

use hybrid vehicles/electric vehicles, and/or use more public transportation.

Sustainable Building Design

add a green roof, decrease the amount of energy to build larger buildings.

Peak demand

peak demand is the time of day where electricity demand is the highest.