Enviro Progress Check 6

Which of the following correctly depicts the nuclear chain reaction that occurs in a nuclear power plant?

In nuclear power production, Uranium-235 is used as fuel. In this image, a neutron interacts with an atom of Uranium-235, releasing two additional neutrons. These neutrons can then interact with additional atoms of Uranium-235, causing a chain reaction.

Which of the following correctly identifies the sequence of energy conversions that occur in a wind turbine?

Kinetic energy → mechanical energy → electrical energy

Which of the following best describes the total consumption of all fossil fuels in 2040 compared to the consumption of nuclear energy in 2040?

Predicted consumption of fossil fuels (liquid, natural gas, and coal) is approximately 645 quadrillion BTUs in 2040, and predicted nuclear consumption is approximately 50 quadrillion BTUs . (248 BTUs from liquid fuels + 215 BTUs from natural gas + 180 BTUs from coal) / 48BTUs = 12.86 BTUs, so almost 13 times greater.

Which of the following statements about the global distribution and use of fossil fuels is best supported by the data on the map?

Saudi Arabia and Australia produce large volumes of fossil fuels with relatively low energy demand.

Based on the data above, approximately how much greater is the average cost of electricity produced in the United States from offshore wind than from hydroelectric power?

The average cost of energy produced from offshore wind farms is $197MWh. The average cost of energy produced from hydroelectric power is $84MWh. Therefore, wind energy is 2.3 times more expensive 197 / 84 = 2.3

Which of the following is the approximate projected rate of change in renewable energy consumption from 2010-2040 ?

The change in projected renewable consumption (about 70 quadrillion) was divided by the change in time (30 years). 130 − 60 / 30 years = 2.33 quadrillion BTUs

Which of the following statements correctly describes a difference between biomass-fired power plants and traditional fossil-fuel-burning power plants, such as coal-fired plants?

The operational costs of biomass plants are very high when compared with traditional fossil fuel plants.

At which of the following locations in the nuclear power plant would an accident most likely result in the release of fission products?

The reactor vessel holds the uranium fuel that is undergoing fission reactions that result in heat production.

A state is looking to reduce the cost of transportation, which uses 7.10×1014 BTUs per year. Currently the cost of 106 BTUs is $20.00. How much will the state save in one year if they implement regulations requiring all transportation methods to be 20% more efficient?

The state is requiring a 20% reduction in current energy use. That would make the current energy use (7.10 × 10^14 BTUs × 0.20) = 1.42 × 10^14 BTUs If the current cost of one million BTUsBTUs is $20, then 1.42 × 10^14 / 1 × 10^6 = 1.42 × 10^8 × $20 = $2.84 × 10^9 or 2.84 billion dollars in savings.

Which of the following are often used for energy storage of wind power?

batteries

What is cogeneration?

the use of a power plant to generate electricity and useful heat at the same time

A hydrogen fuel cell-powered car driving on a highway is different from gasoline-powered cars because hydrogen fuel cell-powered cars only emit

water vapor and heat

In the diagram above, which letter correctly identifies the step where kinetic energy is converted to mechanical energy?

C, the turbine The kinetic energy of the water molecules causes the turbine blades to spin, converting kinetic energy to mechanical energy.

Which of the following describes a step in the generation of electricity using fossil fuels that can most directly lead to an environmental problem?

Fossil fuel is burned to boil water.

Which of the following best describes a potential advantage of using geothermal energy instead of solar farms for power generation?

Geothermal energy can be harnessed without destroying large tracts of habitat, whereas solar farms require large amounts of space.

Geothermal energy is used to run large and complex power stations as well as small and relatively simple pumping systems. Which of the following most accurately explains how geothermal energy is produced and utilized in these applications?

Geothermal energy uses the natural insulating power of Earth to create temperature differentials that are used to heat buildings in the winter and cool them in the summer.

Which of the following is required to convert geothermal energy into electricity?

Groundwater

Which of the following best explains energy transformation in hydrogen fuel cells?

Hydrogen reacts with oxygen to produce water, which releases energy

Refrigerator A uses 500 watts per hour when the motor is operating. The motor needs to run an average of 12 hours per day, every day, to stay at a constant, cold temperature. This model of refrigerator lasts an average of 20 years before it needs to be replaced and costs $1,000. Each kWh of electricity costs $0.12. How many kilowatt hours (kWh) per year does refrigerator A use?

The usage is converted from WW to kW . Then the value is multiplied by the number of hours the motor runs per day and then by the number of days in a year. 500W × 1kW / 1,000W × 12hours / 1 day × 365 days / 1 year = 2,190kWh .

The homeowner is considering purchasing a new model of refrigerator, Refrigerator B. This model uses 50 percent less energy per year. Which of the following would be the estimated cost savings for the homeowner in a year if she replaces Refrigerator A with Refrigerator B?

This value is obtained by taking the annual energy usage for refrigerator A (as determined in the previous question) multiplying it by the cost per kWH and then dividing it by 2 to account for the statement that refrigerator B is 50% more efficient. The cost should be half as much for refrigerator B. (2,190kWH×$0.12) / 2 = $131.40

Which of the following best describes how a homeowner using an off-the-grid PV solar system, as seen in the graph above, can power a home between 9:00 PM and 6:00 AM?

Using excess energy from a sunny day stored in batteries for power, batteries are the standard way to store energy for times when PVPV is not generating.

Which of the following is an example of the process of cogeneration?

Using wastewater from electricity production for heating homes

Which of the following best describes an environmental problem that is often linked to the process of fracking?

Wastewater from fracking operations is injected into porous rock formations, which can induce seismic activity.