AP Environmental Science Test: Energy Resources & Consumption

The correct answer is (E). As of 2016, 15% of electricity generated in the US was from renewable sources. Hydroelectric accounted for 44% of renewable electricity generation. The most common type of hydroelectric power plant uses a dam on a river to store water in a reservoir. Water is released from the reservoir and flows through a turbine, spinning it, which in turn activates a generator to produce electricity. Here is the contribution of all sources:

• Hydro 44%
• Wind 37%
• Biomass 10%
• Solar 6%
• Geothermal 3%

The correct answer is (E). As of 2018, France had 58 operating nuclear reactors and a population of about 67.2 million. The United States and Japan had 99 and 42 operating nuclear reactors, with populations of about 325.7 million and about 127 million, respectively. The French government has focused on nuclear power because of France’s limited natural energy resources.

The correct answer is (D). The predominant sources of fuel for electricity generation in the United States are natural gas and coal. As of 2016, coal and natural gas combined to account for about 64% of the electricity produced in the United States. Nuclear accounts for approximately 20%.

The correct answer is (D). There are four major types of coal: lignite, sub-bituminous, bituminous, and anthracite. Peat is composed mainly of wetland vegetation: primarily bog plants which include mosses, shrubs, and sedges. Peat is the precursor to coal.

The correct answer is (A). The burning of natural gas does release pollutants. The advantage is that it burns cleaner than other fossil fuels, producing half the carbon dioxide as coal and about a third less than oil. It also emits fewer amounts of toxic chemicals like nitrous oxides and sulfur dioxide.

The correct answer is (E). Used nuclear fuel is stored at the nation's nuclear power plants in steel-lined, concrete pools filled with water or in massive, airtight steel or concrete-and-steel canisters. In the mid-1980s, plans were made to store the majority of the spent nuclear fuel at a central repository underneath Yucca Mountain in Nevada. But the project languished primarily due to opposition from Nevada residents who don’t want to import this dangerous material. Critics of the plan also worry that natural forces such as erosion and earthquakes could make the storage facility unstable. These nuclear isotopes can remain hazardous to humans for hundreds of thousands of years.

The correct answer is (B). Oil production in the U.S. peaked in 1970 with an average of 9.6 million barrels of oil produced per day. The Department of Energy is predicting that 2018 will see a new peak in U.S. oil production.

The correct answer is (C). The yaw drive is an important component of the wind turbines' yaw system. To ensure the wind turbine is producing the maximal amount of electric energy at all times, the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. The wind turns the blades, which are connected to the gearbox, which in turn is connected to the generator. The gearbox transfers mechanical energy to the generator. The generator converts mechanical energy into electricity.

The correct answer is (B). Passive solar design uses sunlight without active mechanical systems. This is in contrast to active solar design which uses external sources of energy to power blowers, pumps and other types of equipment to collect, store and convert solar energy.

The correct answer is (E). Electromagnetic energy is reflected or emitted from objects and travels through space in waves. Thermal energy is heat which results from the internal energy in substances. Chemical energy is the energy stored in bonds between atoms in a molecule. Mechanical energy includes potential (stored energy) and kinetic energy (energy in motion).

The correct answer is (A). Coal is used for about 30% of electric generation in the United States, making it the the second most commonly used fuel. However it accounts for 68% of carbon dioxide emissions. Natural gas is used to produce about 32% of US electricity, but only accounts for 30% of CO₂ emissions.

The correct answer is (C). Coals are ranked from low to high in this order: Lignite, sub-bituminous, bituminous, anthracite. Lower ranked coals are softer, lighter, contain less carbon, and have less energy content than higher ranked coals.

Coal starts off as peat. After a long amount of time, heat, and burial pressure, it is metamorphosed from peat to lignite. Lignite is called "immature" coal at this stage of development because it is rather light in color and remains soft. As time passes, lignite increases in maturity by becoming darker and harder, and is then classified as sub-bituminous coal. With more time, pressure, and heat, more chemical and physical changes occur and the coal is classified as bituminous. At this point the coal is dark and hard. Anthracite is the last of the classifications, when the coal has matured completely. Anthracite coal is very hard and shiny.

The correct answer is (B). Oil is also referred to as petroleum and crude oil in the United States. It is produced by the decomposition of organic material under high temperature and pressure for millions of years.

The correct answer is (C). Natural gas is lighter than oil, and found above oil in petroleum deposits. Its two largest uses in the United States are electricity generation and industrial processes. Natural gas is considered a “clear fuel” because it contains fewer impurities and emits almost zero sulfur dioxide or particulates during consumption.

The correct answer is (A). The core of a nuclear reactor contains up to 50,000 fuel rods.

The correct answer is (E). It is true that nuclear power produces very little water pollution. Estimates show that economically accessible uranium supplies could power nuclear reactors for about 200 years at current rates of consumption Nuclear power releases a small amount of CO₂ (only 1/6 of the amount produced by fossil fuels). Nuclear wastes are not recyclable; they are very difficult to dispose of. Finally, uranium is not a renewable resource.

The correct answer is (A). Biogas is produced by anaerobic digestion of organic materials. Biomass is the burning of living or recently living organisms such as yard clippings and wood chips. Biofuel is fuel produced by living organisms such as corn or sugarcane. Geothermal energy utilizes the heat contained in underground rock. Synfuel, or synthetic fuel, is any fuel produced from coal, natural gas or biomass through chemical conversion.

The correct answer is (C). Active solar heating systems involve the use of solar collectors, such as photovoltaic solar cells, to absorb solar energy. The other methods listed are passive, in that they do not include any mechanical heating devices. Passive solar heating involves incorporating building designs that absorb heat and then slowly release it to maintain a consistent temperature in the building.

The correct answer is (C). Wind energy is the fastest growing source of electricity in the world. It has risen from about 6.1 gigawatts in 1996 to nearly 540 gigawatts at the end of 2017.

The correct answer is (D). It is true that many renewable resources have been used by humans for thousands of years to produce energy. Before humans started using fossil fuels, the only available source of energy was wood, plants, animal manure, and animal oils.

Most renewable energy sources are nondepletable, such as wind and solar. The construction and operation of renewable energy projects does create some pollution. However, these risks are less than that of using fossil fuels. Finally, in 2015, renewable energy resources accounted for approximately 12.5% of the energy used worldwide.