APES Energy Review Questions

• What are the two types of mechanical energy• Potential and kinetic energy

• What is chemical energy?• Energy stored in bonds between atoms in a

molecule

• What is electrical energy?• Energy that results from the motion of

electrons

• Nuclear energy is stored in the nuclei of atoms. It is released by

• Splitting or joining atoms

• How does electromagnetic energy travel?• In waves

• What is power and its most common unit?• Amount of work done per time and the unit is

the kilowatt-hour (kWh)

• The unit of energy used in the U.S. is the • Btu (British Thermal Unit)

• What is the Btu?• Amount of heat required to raise the

temperature of 1 pound of water by 1oF.

• What is a watt?• Approximately 3.4 Btu/hr.

• What is one horsepower?• 2,540 Btu/hr or 746 watts of power

• How much is a “ton” in many air-conditioning applications used in home?

• 12,000 Btu/hr

• The amount of energy expended by a 1 kilowatt (1000 watts) device over the course of one hour and often measured in the context of power plants and home energy bills

• Kilowatt hour (kWh) (electrical)

• Nuclear power plant measurement of energy• Thermal watt

• Thorpevill is a rural community with a population of 8,000 homes. It gets its electricity from a small, municipal coal-burning power plant just outside of town. The power plant’s capacity is rated at 20 megawatts with the average home consuming 10,000 kilowatt hours (kWh) of electricity per year. Residents of Thorpeville pay the utility $0.12 per kWh. A group of entrepreneurs is suggesting that the residents support a measure to install 10 wind turbines on existing farmland. Each wind turbine is capable of producing 1.5 MW of electricity. The cost per wind turbine is $2.5 million dollars to purchase and operate for 20 years.

• (a) The existing power plant runs 8,000 hours per year. How many kWh of electricity is the current plan capable of producing?

• You need to show your work as follows or no points will be given for guesswork.

• 20 MW x 1 X 106 watts x 1kW = 2 x 104 kW• 1 1 MW 103 watts

• (2 X 104 kW) x 8,000 hours = 16,000 x 104 kWh/yr• 1 1 yr• = 1.6 x 108 kWh/yr

• (b) How many kWh of electricity do the residents of Thorpeville consume in one year?

• 8 x 103 homes x 1 x 104 kWh/home = 8 x 107 kWh/yr• 1 1 yr

• (c) Compare answers (a) and (b). What conclusions can you make?

• Power plants produces 1.6 x 108 kWh per year. The residents, however, only use 8 x 107 kWh per year. This leaves a surplus of 1.6 x 108 – 8 x 107 = 8 x 107 kWh in one year which can be sold to other towns. At a rate of $0.12 per kWh, this provides a surplus of 8 x 107 kWh x $0.12/kWh = $0.96 x 107 = $9,600,000

• Differences between Thorpeville’s consumption and the power plant’s output could be attributed to:

• Compensation for line loss• More energy during peak hours• Planning for possible future growth of town

• (d) Assuming that the population of Thorpeville remains the same for the next 20 years, and the electricity consumption remains stable per household, what would be the cost (expressed in $/kWh) of electricity to the residents over the next 20 years if they decided to go with wind turbines?

• From part (b) your answer is 8 x 107 kWh/yr.

• kWh for 20 yrs =8 x107 kWh x 20 yrs = 1.6 x109 kWh• year• Direct cost for 20 years = 10 turbines x $2.5 x 106

• turbine• = $2.5 x 107 • Cost/kWh = $2.5 x 107 = $1.6 x 10-2/kWh • 1.6 x 109 kWh • = $0.016kWh

• (e) What are the pros and cons of the existing coal-burning plant compared with the proposed wind farm?

• The electricity produced from the wind turbines costs $0.016 per kWh, but each homeowner would also have to pay $25,000,000/8,000 homes = $3,125.00 over 20 years ($156.25/yr) to pay for the wind turbines. 10,000 kWh at $0.016 per kWh for electricity produced from wind turbines = $160 plus $156.25 per year to pay for the wind turbines = $316.25 per year

• Electricity from the coal-burning plant costs $0.12 per kWh. 10,000 kWh of electricity per year from the coal-burning plant costs $1,200 per year. Clearly, electricity produced from wind turbines is much cheaper.

• Wind : zero emissions, wind is free, no heavy metals, no thermal pollution and multiple use of land

• Coal : produces air pollution, specially SO2 and NOx • As labor prices increase, the price of coal would also increase in the next

20 years• Coal-burning plants produce heavy metals such as mercury, lead, and

cadmium pollution along with radioactive contaminants• Coal produces thermal pollution to local streams• Cannot utilize the concept of multiple use of land

• Laws of thermodynamics• First law – energy cannot be created nor destroyed• Second law – when energy is coverted from one

form to another, a less useful form results.

• Can energy be recycled?• NO

• What percent of gasoline is converted into mechanical energy to make the car move?

• 20%

• What was the original source of energy up until the Industrial Revolution?

• wood

• What was the predominant source of energy during the Industrial Revolution?

• coal

• What is the predominant source of energy in this day and age?

• petroleum

• Why did the U.S. resort to importing petroleum and natural gas after the 1950s?

• Energy consumption began to outpace domestic production

• Who uses the most energy in the U.S.?• Industry followed by transportation, then

residential and finally commercial use

• Who are the leading petroleum consumers?• U.S., followed by former U.S.S.R., then Japan,

and China

• In the U.S. most of the energy comes from• Nonrenewable energy sources such as coal,

petroleum, natural gas, propane, and uranium.

• Renewable energy sources include• Biomass, geothermal energy, hydropower,

solar energy, and wind energy

• Renewable energy is called that because they• Are replenished in a short time

• Clean coal technology refers to processes that• Reduce the negative environmental effects of

burning coal

• What does washing coal remove?• Minerals and impurities and capturing the

sulfur dioxide and carbon dioxide from the flue gases

• What is the Future-Gen project?• A project designed to build a prototype zero-

emission, coal-fired 275 MW power plant that produces hydrogen and electricity using carbon capture and storage technology.

• What is methane hydrate?• Methane locked in ice

• Where do methane hydrates form?• On land in permafrost regions and beneath

the ocean floor at water depths greater than 1,640 feet (500 m) where high pressures dominate

• How much methane is bound in hydrates?• 3,000 times the volume of methane in the

atmosphere which some believe there is enough to supply energy for hundreds or thousands of years.

• What is the primary waste product of burning natural gas?

• Carbon dioxide

• Why is natural gas becoming more in demand?

• Its expanded use in transportation fuel and potentially as a source of alternative liquid fuels and a source of hydrgen for fuel cells

• What is oil shale?• A sedimentary rock that is not really a shale

that contains an organic material called kerogen which when heated in the absence of air turns into oil

• How much oil can be retrieved from oil shale?• 3 trillion barrels with 750 billion found in the

U.S.

• Where is the oil shale found in the U.S.?• Wyoming, Utah, and Colorado

• Where are the largest reserves of oil shale found in the world?

• Estonia, Australia, Germany, Israel and Jordan

• What are the impacts of mining for oil shale?• It involves surface mining which degrades the

land and causes pollution

• What is the net energy yield of producing oil through oil shale?

• Moderate since energy is required for blasting, drilling, crushing, heating the material and disposing of waste material, and then environmental restoration

• What is in-situ methods of extracting oil shale and how does it impact the environment?

• Processing in place without having to transport it a power plant. It may reduce some environmental impacts but can cause groundwater pollution

• What are tar sands?• Tar sands containing bitumen which is a

semisolid form of oil that does not flow

• How are tar sands mined?• strip-mining techniques which highly degrades

the environment

• How does in-situ methods extract the bitumen?

• Steam is used to extract the bitumen

• What percent of tar sands is sulfur?• 5%

• What is the net energy yield of producing oil from tar sands?

• Moderate because energy is required for blasting, drilling, crushing, heating the material, disposing of waste material, and environmental restoration.

• What types of enviornmental problems can arise once oil is extracted from oil shale and tar sands?

• Pollution, acid rain, and global warming

• What drives the price of energy?• Principle of supply and demand

• What brings on an energy crisis?• A failure of world markets to adjust prices in

response to shortages

• Who controls the oil supply?• Nations with significant reserves of easily

extractable oil such as Saudi Arabia and Venezuela who belong to an association of oi-producing countries known as OPEC

• What does OPEC stand for?• Organization of Petroleum Exporting Countries

• How many energy crises have we experienced and why?

• 5 and due to political reasons, war, and corporate corruption

• How long are oil reserves going to last in the U.S.?

• 25 years

• How does coal form?• By the decomposition of ancient (286 million

year old) organic material under high temperture and pressure

• What is the origin of the sulfur content in the coal?

• Decomposition of hydrogen sulfide by anaerobic bacteria became trapped in the coal

• What are the stages of coal formation?• Peat – lignite – bituminous coal – anthracite

• Which of the three forms of coal is not a sedimentary rock?

• Anthracite – it’s a metamophic rock

• How is lignite different from bitumious coal?• Lignite (brown coal) has the lowest heat

content and a higher sulfur content than bituminous coal

• What percent of the U.S. reserve does bituminous coal consitute?

• 50%

• What percent of the world’s energy constitutes coal?

• 25%

• How much coal is used in the U.S. for power plants to produce electricity?

• 87%

• How much reduction in the release of sulfur-containing gases does the Clean Air Act require?

• 90%

• Describe how coal can be cleaned.• Washing coal prior to burning, redesigning

boilers (fluidized bed combustion), and scrubbing or adding limestone or lime into the effluent

• How does oil form?• Decomposition of deeply buried organic

material (marine organisms) under high temperatures and pressures for millions of years

• Compounds derived from oil are know as• petrochemicals

• What are petrochemicals used for?• Manufacture of paints, drugs, plastics, etc.

• How is natural gas formed?• Decomposition of ancient organic matter

under high heat and pressure and is usually found in association with oil deposits

• What are the two methods of mining coal?• Surface mining and underground mining

• Where is oil usually found?• Trapped in a layer of porous sandstone, which

lies just beneath an anticline or folded layer of some nonporous layer such as limestone

• In other formations, the oil is trapped by a fault

• Where is the natural gas usually found?• Above the oil

• Why does oil gush outward when tapped by drilling equipment?

• It is under pressure due to saltwater under the oil

• How is oil cracked?• Cracking involves separating the components

of oil by their boiling points

• What is produced from refining crude oil?• Gasoline, heating oil, diesel oil, asphalt, etc

• How much natural gas does the U.S. Produce each year?

• 20 trillion cubic feet

• How long is coal expected to last at current rates of consumption?

• 300 years with China having the largest reserve

• What percent of oil is found in just 1% of all fields?

• 65% in the Middle East

• Who has the largest percent of natural gas reserves?

• Russia and Kazakhstan with 40%, 25% in the Middle East and 3% in the U.S.

• What is a synfuel?• A liquid fuel synthesized from a nonpetroleum

source such as coal, natural gas, oil shale, or waste plastics. Shale oil is an example of a synfuel.

• How is synthetic natural gas produced?• Coal liquefaction

• What are the pros of SNG, methanol, or synthetic gasoline?

• Easily transported through pipelines• Produces less pollution• Can produce gasoline, diesel, or kerosene

directly without reforming or cracking

• What are the cons of SNG, methanol, or synthetic gasoline?

• Low net energy yield and requires energy to produce SNG

• Plants are expensive to build• Product is more expensive than petroleum

products

• How is nuclear energy used to produce electricity?

• When the atom is split and controlled, the heat that is produced is used to produce steam that turns generators that then produce electricity

• What is the upside of the potential nuclear energy contained in nuclear fuel?

• It is 10 million times more than that of more traditional fuel sources such as coal and petroleum

• What is the downside of nuclear energy?• The nuclear wastes remain highly radioactive

for thousands of years and difficult to dispose

• What are the common nuclear fuels?• U-235, U-238, and Pu-239

• The minimum U-235 required for a chain reaction is called the

• Critical mass

• The function of the moderator in a nuclear reactor is to

• Slowing down the speed of the neutrons

• The fission of just one U-235 atom generates • 3.2 x 10-11 joules of energy

• The least abundant type of natural uranium in the Earth’s crust is

• U-235

• Uranium that has been processed to separate out U-235 is known as

• Enriched uranium

• How much U-235 do nuclear weapons contain?

• 85%

• How much U-235 do nuclear power plants contain?

• 3%

• The half-life of U-235 is • 700 million years

• The most common isotope of uranium is• U-238

• The half-life of U-238 is• 4.5 billion years

• What does U-238 decay into when hit with a neutron?

• Pu-239

• The half-life of Pu-239 is• 24,000 years

• Pu-239 is produced in• Breeder reactors from U-238

• About 1/3 of the total energy produced in a typical commercial nuclear power plant comes from

• The fission of plutonium

• Why do control rods in nuclear power plant need to be changed frequently?

• The buildup of Pu-239 which is used in nuclear weapons and Pu-240, a contaminant

• Why has there been a decline in building new nuclear power plants with the exception of China?

• Cost overruns • higher than expected operating costs • safety issues • disposal of nuclear wastes• perception as a risky investment

• Name 4 types of nuclear reactors.• Light-water reactors• Heavy-water reactors• Graphite-moderated reactors• Exotic reactors

• What do all reactors have in common?• The core• Contains up to 50,000 fuel rods with each pellet having the

energy equivalent of a ton of coal• Uranium oxide as a fuel• 97% being U-238 and 3% being U-235• Control rods• Usually made of boron that move in and out of the core to

absorb neutrons and slow down reaction• A moderator• A medium that reduces the velocity of the fast neutrons,

thereby turning them into thermal neutrons capable of sustaining a nuclear reaction. Can be water, graphite (can produce Pu for weapons or deuterium oxide (heavy water)

• Coolant• Removes heat and produces steam to generate electricity

• What is the moderator and the coolant in a light-water reactor?

• Light water (H2O)

• Name the two light-water reactors.• Pressurized-water reactors (PWR) and the

boiling-water reactor (BWR)

• What is the coolant and moderator in a Heavy-water reactor?

• Heavy water (D2O)

• What is the coolant, moderator, and fuel in graphite-moderated reactor?

• Light water for cooling and graphite for moderation and uranium for fuel

• Why are these type of reactors no longer in use?

• They require no separated isotopes such as enriched uranium or heavy water and proved to be very unstable and led to such disasters as Chernobyl in Russia

• What are the pros of nuclear power?• No air pollutants if operating correctly• Releases about 1/6 the CO2 as fossil fuel

plants, thus reducing global warming• Water pollution is low• Disruption of land is low to moderate

• What are the disadvantages of nuclear power?• Nuclear wastes takes millions of years to degrade. • Problem of where to store wastes and keep them

out of hands of terrorists• Current facilities have a life span of only 15-40 years• Low net-energy yield – energy required for mining

uranium, processing ore, building and operating plant, dismantling plant, and storing wastes

• Safety and malfunction issues

• What happened in Chernobyl, Ukraine in 1986?• Explosion in nuclear power plant sent a highly

radioactive cloud of debris throughout northern Europe

• About 32,000 people died and 62,000 square miles remain contaminated

• About 500,000 people were exposed to dangerous levels of radiation

• Cause of meltdown was due to bad design and human error

• How does nuclear fusion occur?• When extremely high temperatures are used to

force nuclei of isotopes of lightweight atoms to fuse together, which causes large amounts of energy to be released

• What is the waste product of a fusion plant producing 1,000 MW of electricity?

• 4 pounds of harmless helium

• What is the waste product of a coal-fed electrical generating plant producing 1000 MW of electricity?

• 30,000 tons of CO2 gases, 600 tons of SO2 gases, and 80 tons of NO2 gas.

• Legislation that covers all nonmilitary nuclear facilities constructed before 2026 that indemnifies the nuclear industry against all liability claims arising from nuclear accidents while ensuring compensation coverage for the general public through no-fault insurance – the first $10 billion coming from the nuclear industry and anything above $10 billion coming from the U.S. Government

• Price-Anderson Nuclear Indemnity Act (1957)

• Dams built to trap water, which in turn is then released and channeled through turbines that generate electricity is known as

• Hydroelectric power

• What percentage of hydropower supplies electricity for the U.S.?

• 10%

• List the pros of hydropower.• Dams control flooding• Low operating and maintenance costs• No polluting wastes products• Long life spans• Moderate to high net-useful fuel• Areas of water recreation

• What are the cons of hydropower?’• Dams create large flooded areas behind the dam

from which people are displaced• Water is slow moving and can produce pathogens• Dams destroy wildlife habitat and keep fish from

migrating• Sedimentation requires dredging. Prevents

sediments from reaching downstream and enriching the floodplain where crops are planted

• Expensive to build• Destroys wild rivers• Large-scale projects are subject to earthquakes

• The process of flood control where the stream is straightened and deepened is called

• channelization

• What are the cons of channelization?• Removes bank vegetation and increases

stream velocity, which causes erosion• May increase downstream flooding and

sedimentation which negatively impacts aquatic environments

• Embankments that are raised to prevent a river from overflowing are called

• levees

• What can happen with levees?• It may contain the river but it will increase the

velocity of the stream• They can also break as they did with hurricane

Katrina in 2005

• What is the best way to control floods?• Preserve wetlands that absorb river overflow

and create habitats and maintains biodiversity

• How have dams affected salmon?• They block the migration of the salmon and

have also destroyed their spawning grounds upstream

• How does the changing of the character of rivers affect salmon?

• Dams create warm water pools that are ideal for predators of salmon

• Low water velocity in large reservoirs can also delay salmon migration and expose fish to higher water temperatures and disease

• What are some ways that have been done to reduce the impacts of dams on fish?

• Fish passage facilities and fish ladders that help juvenile and adult fish migrate over or around many dams

• Spilling water at dams over the spillway can help juvenile fish downstream because it avoids sending the fish through the turbines

• Water releases have been used to increase water velocities and reduce water temperatures

• Juvenile fish are also collected and transported downstream in barges and trucks.

• What are the main causes of water loss in dams?

• Evaporation and seepage into porous rock below

• Legislation established dam safety programs and safety

• Water Resources Development Act (1986)

• A joint program of the U.S. EPA and the U.S. DOE designed to protect the environment through energy-efficient products and practices is called

• Energy Star

• What consumes 2/3 of the petroleum consumption in the U.S.?

• transportation

• The average fuel economies of a manufacturer’s fleet of passenger cars or light trucks are called the

• CAFE standards

• What does CAFE stand for?• Corporate Average Fuel Economy

• How are CAFE standards achieved?• Better engine design, efficiency, and weight

reduction

• What kind of savings are result in setting CAFE standards?

• Savings of over 55 billion gallons of fuel annually with a substantial reduction in carbon dioxide emissions of approximately 10%

• Significant improvements in fuel mileage could be achieved by expanding CAFE standards to include

• Streamlining• Reduced tire-rolling resistance• Engine improvements (hybids)• Optimized transmission improvement• Transition to higher voltage automotive electrical

systems• Performance-based tax credits

• What are the parts of a gasoline-electric hybrid?

• The engine is smaller than a gas-only car and used advanced technologies to reduce emissions

• The fuel tank in a hybrid is the energy storage device for the gasoline engine