Unit 6 Flashcards
Nonrenewable Energy Resource
An energy source with a finite supply (fossil fuels and nuclear fuels)
Fossil fuels (and how they form)
A fuel obtained from biological material that became fossilized millions of years ago
(ex: coal, oil, natural gas)
- detritus that is not decomposed gets buried under layers of sediment, subject to heat and pressure– becomes gas
EROEI
A way to determine the energy required to produce a fuel:
Energy obtained from the fuel/Energy invested to obtain the fuel
Cogeneration
The use of a fuel to generate electricity and produce heat.
-efficient
Petroleum
A fossil fuel that is located underground in rocks. It is a liquid mixture of hydrocarbons, water, and sulfur
Crude Oil
Liquid petroleum removed from the ground
Oil (tar) sands
Slow-flowing, thick/sticky deposits of bitumen, mixed with sand, water, and clay
Bitumen
A degraded form of petroleum that forms when petroleum deposit is not capped with nonporous rock. Petroleum migrates to the surface of Earth and is modified by bacteria
Fission
A nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into 2+ parts, releasing additional neutrons and energy in the form of heat
Fuel Rods
A cylindrical tube that encloses nuclear fuel within a nuclear reactor
Control Rods
A cylindrical device inserted between the fuel rods in a nuclear reactor to absorb excess neutrons and slow or stop the fission reaction
Fractional Distillation
Separation of a liquid mixture based on boiling point
Hydraulic Fracturing
Method of extracting natural gas from shale rock. (use water to break rock)
*lots of freshwater used
Natural Gas
Mostly methane, underground, used as fuel, found with petroleum (above oil)
Energy Efficiency
using technology that requires less energy to perform the same function
Moderator (in a nuclear reactor) **FIX
A substance (water, graphite) that slows down neutrons to continue the fission chain reaction at a constant rate. Important so the reaction does not go too fast and lead to a meltdown.
High and low level radioactive waste
High: toxic, nuclear waste
Low: low radioactivity, no significant danger
Sub-bituminous
In between lignite and bituminous coal
Liquid Petroleum Gas
A group of hydrocarbon gases obtained from crude oil refining
Give the formula for calculating EROEI. What type of value is desired when calculating EROEI?
Energy obtained from the fuel/Energy invested to obtain the fuel
better to have a high EROEI because you will obtain a high amount of energy by investing a low amount of energy
Explain the process of electricity generation.
Atoms, the tiny building blocks of all things on Earth, are composed of protons, neutrons, and electrons. Electrons, which have a negative charge, are moved between atoms by electrical and magnetic forces. This produces an electric current. Power plants use turbines to rotate magnets inside copper wire. This creates electron movement, which in turn produces electricity.
What is cogeneration?
Simultaneous production and use of two different energy forms (from one energy source within the same facility). EFFICIENT
The second energy source, which is produced as a byproduct of the first, is used rather than wasted
Electrical energy production generates a lot of heat– can be used to raise the temp of gas or water which is used to supply large buildings
List and describe the five types of coal indicating time to form, water and energy content. Indicate which type of coal is preferred for burning and why
Peat: NOT COAL, precursor to coal 0 years, partially decomposed matter (vegetation in forest dies), lowest heat + carbon content, highest moisture,
Lignite: (brown coal) Millions of years, peat becomes buried deeper, compressed into lignite, low sulfur content, limited supplies in most areas
Subbituminous
Bituminous: (soft coal) hundred of millions of years, lignite layers buried deeper, increased pressure compresses lignite into soft, bituminous coal, extensively used as a fuel because of its high heat content, large supplies, normally has high sulfur content
Anthracite (hard coal) 280-380 million years, deeper burial, years of increased pressure, tectonic activity, and heat. This transforms bituminous coal into anthracite coal. It is highly desirable because of its high heat content and low sulfur content; supplies are limited in most areas. Lowest moisture, highest heat and carbon content
What are the advantages and disadvantages of using coal as an energy resource?
Advantages:
coal is energy-dense and plentiful (used to generate electricity, make steel
coal is easy to obtain through surface mining
when coal is extracted from the ground, low cost
it is easy to handle and needs little refining before it is burned
Disadvantages:
negative environmental consequences of tailings from surface mining
when surface coal is used up, subsurface mining becomes necessary. The technological demand price, and negative human health effects increase
Coal releases sulfur into the atmosphere when burned. Trace metals are found in coal (mercury, lead, arsenic). When coal is burned and releases the impurities, increase in sulfur dioxide, increase in air pollutants in atmosphere (ex: particulates)
Lignite and anthracite have low sulfur content. Bituminous coal is higher
Coal companies have attempted to reduce the chemical compounds released in the air by washing their coal in different organic compounds. Some of these compounds can be toxic
Coal burning leaves ash behind. If large accumulation of ash spills, it can destroy houses, requires a lot of $$ to clean up
Air pollution: coal is 60-80% carbon. When burned, converted into CO2. Coal produces more CO2 than oil or natural gas
How is oil obtained from the ground? How is petroleum formed? What is petroleum used for?
Petroleum is formed from the remains of ocean-dwelling phytoplankton. Deposits of phytoplankton are found where porous sedimentary rocks (ex: sandstone) are capped by non-porous rocks. Petroleum fills the pore spaces in the rock when it forms. Geologic events related to tectonic cycle may deform the rock layers, creating a dome shape. Petroleum is less dense than the rock, so over time, it migrates upwards towards the highest point in the porous rock, where it is trapped by the nonporous rock.
Petroleum producers drill wells into a deposit and extract the petroleum with pumps. After extraction, the petroleum is transported to a petroleum refinery by pipeline (if well is on land) or by supertank (if underwater)
Petroleum contains natural gas-extracted and used as fuel
Crude oil (liquid petroleum) can be further refined into a variety of compounds: (tar, asphalt, gasoline, diesel, kerosene) They are distinguished by temperature at which they boil (boiling point). Therefore, they can be separated by heating the petroleum. This process takes place at an oil refinery (large factory). The refining process is complex + dangerous + costly.
Uses of petroleum: mostly transportation, plastics, lubricants, cleaning solvents
Explain the process of fractional distillation in refining crude oil.
Fractional Distillation:
Crude oil is heated to vaporize it
Heated crude oil is put into a fractionating column
As the vapor rises, it cools
When is a substance reaches a height where the temperature of the column equals the boiling point of the substance, it will condenser to form a liquid
The substance with the lowest boiling point will condense at the highest point in the column
Liquids are let out of the column at different heights
What are the advantages and disadvantages of petroleum?
Advantages: Liquid- easy to transport and use. More clean-burning (leaves little contamination) than coal. Produces less CO2 than coal
Disadvantages: Oil contains sulfur and trace metals (mercury, lead, arsenic) and releases them when burned. Where oil is extracted there is risk of spills and leaks. Oil spills in marine water come from runoff from land, rivers, airplanes, and small boats. Destroys habitats of animals living near oil wells or pipelines. Oil fields near villages- crude oil covers ground– health effects
What type of mining is used to obtain the oil?
What are some environmental effects of mining oil?
Oil sand mining: Mining bitumen is much more energy-intensive than conventional drilling for crude oil
(used to obtain Bitumen) Surface mining creates large open pits (open pit mining)
Extracting bitumen from other materials contaminates water
Oil sands require so much energy before arriving at the refinery, a low efficiency system. Also, more CO2 is released than in conventional oil production
What are the advantages and disadvantages of natural gas?
Advantages:
natural gas contains fewer impurities than coal and oil, therefore emits almost no sulfur dioxide or particulates during combustion
Emits less CO2 than coal
Cleanest fossil fuel
Disadvantages:
Natural gas that leaks after extraction is expected to be a contributor to atmospheric methane (absorbs more infrared than CO2)
The process of hydraulic fracturing releases natural gas from host rock. Fracking uses lots of chemicals. Fracking also uses a lot of water, which can become contaminated
There can also be groundwater contamination resulting from the drilling of natural gas wells.
Photovoltaic Cells
a system of capturing energy from sunlight and converting it directly into electricity
Concentrating solar thermal power, disadvantages, how different from thermal power plant
CST systems are a large scale application of solar energy to electricity generations. CST systems use lenses or mirrors and tracking systems to focus the sunlight falling on a large area into a small beam (like magnifying glass). The heat of the concentrated beam is used to evaporate water and produce steam that turns a turbine to generate electricity. They are different from thermal power plants because the energy to produce the steam comes directly from the Sun, rather than from fossil fuels.
Disadvantages:
- Large amount of land required
- Inability to generate electricity at night
-Best in direct sunshine
Geothermal energy
heat energy that comes from the natural radioactive decay of elements deep within Earth (taking advantage of the fact that convection currents bring hot magma toward the surface of Earth which heat up groundwater)
Stored in earth’s mantle, used to heat and cool buildings
Large geothermal plants use steam to turn turbines
Geothermal Heat Pumps: used for homes and buildings
Winter: the water is pumped down into the earth to get heat and distribute to home
Summer: heat of the house is pumped down and distributed to earth
hydroelectricity
electricity generated by the kinetic energy of moving water. It is the second most commonly used form of renewable energy in the U.S
The kinetic energy of moving water is captured by a hydroelectric power plant, where it is used to turn a turbine
Wind energy
energy generated from the kinetic energy of moving air. (Wind turns the blades of a wind turbine and the blades transfer energy to the gear box that in turn transfers energy to the generator that generates electricity. Offshore wind turbines are the most desirable, they are also typically installed in rural areas. They must also be close to electrical transmission lines with enough capacity to transport the electricity they generate to users– grouped together.
hydrogen fuel cells
an electrical-chemical device that converts hydrogen into an electrical current. Combines hydrogen and oxygen gas to create electricity and water
- 2H2+O2 → energy+2H2O
- Current problems: cost, weight of the battery (too heavy will decrease efficiency)
- Other issues: obtaining hydrogen without using fossil fuels, distribution network, storage of the fuel in the vehicle, risk of explosion
