# AP Environmental Science : Other Energy Sources

## Example Questions

### Example Question #1 : Solar Energy

Charlie lives off-grid and gets his electricity from a 5,000 watt gasoline generator, but with the rising cost of fossil fuel, Charlie is looking to convert to solar energy. If a standard solar panel can generate 200 watts, how many panels would Charlie need to purchase if he wants to get the same energy output that he does with his gas generator?

Explanation:

Wattage is a measurement of electricity being generated over time. When compared to the 5,000 watt output of a conventional generator, a single solar panel generating watts cannot generate the same rate of electrical output. As a result, we will need multiple panels to generate an equal amount of electrical output. We can use dimensional analysis to determine how many panels we would need:

This calculation tells us that Charlie will need 25 standard solar panels to generate the same amount of electricity as one gasoline generator.

### Example Question #1 : Solar Energy

An important renewable energy source is solar power. Solar power works by storing sunlight in batteries using which type of cells?

Thermal cells

Eukaryotic cells

Photovoltaic cells

Photovoltaic cells

Explanation:

The correct response is photovoltaic cells. These photovoltaic cells are the reason we can capture and use sunlight to power our homes and cars. Technological advances in photovoltaic cells have made solar energy economically viable over the past decade. Eukaryotic cells are a type of living organisms, while thermal and radiation cells are made-up terms.

### Example Question #1 : Other Energy Sources

Scientists agree that this option holds the most promise for an efficient, cheap, and environmentally safe source of fuel.

Agricultural wastes

Proton pumps

Explanation:

Ethanol can be made from cellulosic—or woody—plants such as switchgrass, poplars, and willows. Cellulose, or plant tissue, sequesters a huge amount of carbon and contains a great deal more energy per unit than corn. Scientists believe that within the next two decades, research will have figured out how to quickly and efficiently break down plant tissue for fermentation into fuel.

Biodiesel made from corn is environmentally safe to burn; however, it requires a great deal of water and resources to grow and harvest.

Agricultural wastes can have a negative impact on air quality due to the pollutants they generate when burned, such as sulfur oxide, nitrogen oxide, and carbon monoxide.

### Example Question #1 : Hydrogen And Fuel Cells

Which of the following is NOT a drawback of utilizing hydrogen as a fuel source?

Hydrogen has a low energy density by volume.

The input of energy to produce hydrogen is often greater than the energy of the resulting hydrogen.

Existing infrastructure for manufacturing and transporting hydrogen is minimal to nonexistent.

Hydrogen has a low energy density by weight.

Hydrogen is very challenging and dangerous to transport.

Hydrogen has a low energy density by weight.

Explanation:

Hydrogen is very challenging to transport and it requires a large energy investment to produce it. While hydrogen has a low energy density by volume, it actually has a very high energy density by weight. This has to do with the fact that hydrogen, discussed in this context, is a gas.

### Example Question #1 : Geothermal Energy

Which of the following is NOT correct about geothermal energy?

While sustainable, geothermal plants do emit small quantities of carbon dioxide and some toxic gases, originally trapped in gas pockets deep below the surface.

Iceland has been able to utilize geothermal to meet over twenty-five percent of their energy demand, in large part because of the geothermal activity of the region.

Fuel consumption of geothermal plants is insignificant when compared to that of coal and natural gas plants.

Geothermal has proven cost-effective in remote communities where importing fuel is challenging and expensive.

Geothermal energy can be harnessed in any region of the world and contribute substantially to the power grid.

Geothermal energy can be harnessed in any region of the world and contribute substantially to the power grid.

Explanation:

Geothermal activity has proven to be a cheap, low-cost and environmentally friendly energy source for communities located in areas with high geothermal activity, particularly where the earth's crust is rather thin (e.g. Iceland); however, this method of harvesting energy is not very economically feasible or possible in areas with little near-surface geothermal activity.

### Example Question #21 : Energy Production And Usage

Which of the following most accurately defines "Synfuel"?

A derivative of waste plastics that results in a form of kerosene

A liquid fuel processed from a non-petroleum material such as coal or waste plastics.

Synthetic fuel, derived exclusively from non-organic sources as opposed to organic sources (e.g. biodiesel, ethanol, etc.)

A counterfeit fuel produced by illegitimate companies that can prove harmful to industry when mixed with fuel reserves

Fuel synthesized in a laboratory as opposed to refined from crude oil