Environmental Science: Renewable Energy
Comparing clean energy sources, impacts, and tradeoffs
Environmental Science: Renewable Energy
Comparing clean energy sources, impacts, and tradeoffs
Environmental Science - Grade 9-12
- 1
Define renewable energy and give three examples of renewable energy sources.
Think about energy sources that are not used up permanently when people use them.
Renewable energy is energy from sources that are naturally replenished on a human time scale. Examples include solar energy, wind energy, hydropower, geothermal energy, and biomass. - 2
A school installs solar panels that produce an average of 120 kilowatt-hours of electricity per day. How many kilowatt-hours will the panels produce in 30 days if the average daily production stays the same?
The solar panels will produce 3,600 kilowatt-hours in 30 days because 120 kilowatt-hours per day multiplied by 30 days equals 3,600 kilowatt-hours. - 3
Compare solar photovoltaic energy and wind energy. Describe one advantage and one limitation of each.
Consider both the energy source and where it can be used effectively.
Solar photovoltaic energy can be installed on rooftops and produces electricity without air pollution during operation, but it produces less electricity at night or during cloudy weather. Wind energy can generate large amounts of electricity in windy areas, but it is intermittent and can affect birds, bats, or nearby communities if poorly sited. - 4
A wind turbine has a rated capacity of 2 megawatts. If it operates at an average capacity factor of 35 percent for 24 hours, how many megawatt-hours of electricity does it produce in one day?
Use energy equals power multiplied by time, then multiply by the capacity factor.
The wind turbine produces 16.8 megawatt-hours in one day. The calculation is 2 megawatts multiplied by 24 hours multiplied by 0.35, which equals 16.8 megawatt-hours. - 5
Explain why renewable energy sources can still have environmental impacts even though they do not burn fossil fuels during operation.
Renewable energy sources can still have environmental impacts because they require land, materials, manufacturing, transportation, and infrastructure. For example, dams can change river ecosystems, wind turbines can affect wildlife, and solar farms can alter habitat if they are not carefully planned. - 6
Look at a proposed energy mix for a town: 40 percent solar, 30 percent wind, 20 percent hydropower, and 10 percent natural gas backup. What percentage of the town's electricity comes from renewable sources?
Add only the percentages for renewable sources.
The town gets 90 percent of its electricity from renewable sources because solar, wind, and hydropower are renewable, and 40 percent plus 30 percent plus 20 percent equals 90 percent. - 7
Describe the difference between energy efficiency and renewable energy. Give one example of each.
Energy efficiency means using less energy to provide the same service, such as replacing incandescent bulbs with LED bulbs. Renewable energy means producing energy from naturally replenished sources, such as generating electricity with solar panels. - 8
A home uses 900 kilowatt-hours of electricity in one month. A rooftop solar system provides 60 percent of that electricity. How many kilowatt-hours come from the solar system, and how many must come from other sources?
Find 60 percent of the total, then subtract from the total.
The solar system provides 540 kilowatt-hours because 900 multiplied by 0.60 equals 540. The remaining 360 kilowatt-hours must come from other sources because 900 minus 540 equals 360. - 9
Explain one reason why energy storage, such as batteries or pumped storage hydropower, is important for solar and wind power.
Energy storage is important because solar and wind power are variable. Batteries or pumped storage can save extra electricity when production is high and release it when production is low, such as at night or during calm weather. - 10
A city is deciding whether to build a large hydropower dam. List two potential benefits and two potential environmental or social concerns.
Think about both electricity production and changes to the river system.
Two benefits of a large hydropower dam are reliable electricity generation and the ability to store water for later use. Two concerns are that the dam can block fish migration, change river habitats, flood land, or require people to relocate. - 11
Biomass is sometimes described as renewable, but it is not always carbon neutral. Explain why.
Biomass can be renewable if plants are regrown, but it is not always carbon neutral because burning biomass releases carbon dioxide immediately. If forests are cut faster than they regrow, or if land use changes release stored carbon, total greenhouse gas emissions can increase. - 12
A community wants to reduce carbon dioxide emissions from electricity. Its coal power plant emits about 1 kilogram of carbon dioxide per kilowatt-hour. If the community replaces 50,000 kilowatt-hours of coal electricity with wind electricity, about how many kilograms of carbon dioxide emissions are avoided?
Multiply the electricity replaced by the emissions per kilowatt-hour.
About 50,000 kilograms of carbon dioxide emissions are avoided because each kilowatt-hour of coal electricity emits about 1 kilogram of carbon dioxide, and 50,000 kilowatt-hours are replaced. - 13
A map shows that one region has strong steady winds, another has frequent cloudy weather, and another has hot underground rock near the surface. Match each region with the renewable energy source that is likely to be most suitable: wind, solar, or geothermal.
Match each energy source to the natural condition it depends on most.
The region with strong steady winds is most suitable for wind energy. The region with frequent cloudy weather may be less suitable for solar energy, while the region with hot underground rock near the surface is most suitable for geothermal energy. - 14
Explain why a renewable energy plan should include considerations of environmental justice.
A renewable energy plan should include environmental justice because the benefits and burdens of energy projects are not always shared equally. Communities should have fair access to clean energy jobs and lower pollution, and they should not be unfairly burdened by land use changes, noise, costs, or infrastructure impacts. - 15
The table shows estimated costs for electricity sources: solar at 4 cents per kilowatt-hour, wind at 3 cents per kilowatt-hour, geothermal at 7 cents per kilowatt-hour, and natural gas at 6 cents per kilowatt-hour. Which renewable source listed has the lowest cost, and what other factor besides cost should planners consider before choosing it?
Identify the lowest cost first, then think about practical limits in a real location.
Wind has the lowest listed cost among the renewable sources at 3 cents per kilowatt-hour. Planners should also consider factors such as local wind availability, land use, wildlife impacts, grid connection, reliability, and community support.