Science: Renewable vs Non Renewable Energy Sources
Comparing energy sources, impacts, and tradeoffs
Science: Renewable vs Non Renewable Energy Sources
Comparing energy sources, impacts, and tradeoffs
Science - Grade 9-12
- 1
Classify each energy source as renewable or non renewable: coal, wind, natural gas, solar, uranium, geothermal, petroleum, and hydropower.
Ask whether the source can be naturally replaced quickly enough for continued human use.
Coal, natural gas, uranium, and petroleum are non renewable because they are used faster than they are naturally replaced. Wind, solar, geothermal, and hydropower are renewable because they are replenished naturally on a human time scale. - 2
Explain the main difference between renewable and non renewable energy sources in terms of time scale and supply.
Renewable energy sources are replenished naturally within a short time scale, such as sunlight or wind. Non renewable energy sources form over millions of years or exist in limited amounts, so their supply can be depleted. - 3
A town currently gets most of its electricity from coal. Name two environmental problems caused by burning coal for electricity.
Think about both global effects and local air quality effects.
Burning coal releases carbon dioxide, which contributes to climate change. It can also release air pollutants such as sulfur dioxide, nitrogen oxides, and particulate matter that can harm human health and cause acid rain. - 4
The diagram shows the Sun shining on solar panels, wind turning turbines, water behind a dam, and coal being burned in a power plant. Identify which examples in the diagram are renewable and which are non renewable.
Solar panels, wind turbines, and hydropower from the dam are renewable examples. Coal burned in the power plant is non renewable. - 5
Biomass is often classified as renewable. Explain why biomass can be renewable, and describe one condition under which it may not be sustainable.
Renewable does not always mean environmentally harmless.
Biomass can be renewable because plants and organic matter can regrow after being harvested. It may not be sustainable if forests or crops are harvested faster than they regrow, or if land use causes habitat loss and high carbon emissions. - 6
A 500 megawatt coal power plant operates at an average capacity factor of 85 percent for 24 hours. A 500 megawatt wind farm operates at an average capacity factor of 35 percent for the same time. Calculate the energy produced by each in megawatt-hours.
Energy produced equals power rating multiplied by time multiplied by capacity factor.
The coal plant produces 500 megawatts × 24 hours × 0.85 = 10,200 megawatt-hours. The wind farm produces 500 megawatts × 24 hours × 0.35 = 4,200 megawatt-hours. - 7
Why might a wind farm with the same maximum power rating as a coal plant produce less electricity over a week?
A wind farm may produce less electricity because wind speed changes over time and turbines do not always operate at full capacity. A coal plant can often run more steadily when fuel is available, so its capacity factor is usually higher. - 8
Use the bar graph to compare carbon dioxide emissions per kilowatt-hour from coal, natural gas, solar, wind, and nuclear power. Which two sources are likely to have the highest direct emissions, and why?
Direct emissions come mainly from combustion.
Coal and natural gas are likely to have the highest direct emissions because both are fossil fuels that release carbon dioxide when burned. Coal usually releases more carbon dioxide per kilowatt-hour than natural gas. - 9
List one advantage and one limitation of solar energy for an electric grid.
One advantage of solar energy is that it produces electricity without direct air pollution or fuel costs during operation. One limitation is that solar panels only generate power when sunlight is available, so storage or backup power may be needed. - 10
List one advantage and one limitation of nuclear energy. Include whether it is renewable or non renewable.
Focus on the fuel source and the waste products.
Nuclear energy is non renewable because it uses uranium fuel, which is limited. One advantage is that nuclear power produces large amounts of electricity with low direct carbon dioxide emissions, and one limitation is that it creates radioactive waste that must be safely managed. - 11
A pie chart shows an energy mix: 40 percent natural gas, 25 percent coal, 15 percent wind, 10 percent nuclear, 5 percent solar, and 5 percent hydropower. What percent of the mix is renewable energy?
Add only the sources that are naturally replenished on a human time scale.
The renewable sources are wind, solar, and hydropower. Their total is 15 percent + 5 percent + 5 percent = 25 percent, so 25 percent of the energy mix is renewable. - 12
Explain why energy storage can make renewable energy sources such as solar and wind more useful for the electric grid.
Energy storage can save extra electricity produced when solar or wind output is high. The stored energy can then be used when sunlight or wind is low, which helps keep electricity supply more reliable. - 13
The map shows a sunny desert region, a windy coastline, a mountain river, and a flat urban area with little open land. Match the best renewable energy option to each location and explain one match.
Consider the natural resource available in each location.
The sunny desert region is well suited for solar power, the windy coastline is well suited for wind power, and the mountain river is well suited for hydropower if environmental conditions allow it. The flat urban area with little open land may use rooftop solar or imported renewable electricity. For example, the desert matches solar power because it receives strong sunlight over many days of the year. - 14
A community wants to reduce greenhouse gas emissions but is concerned about cost and reliability. Write a short recommendation for an energy plan that uses at least two different energy sources.
A balanced plan can use more than one source to reduce weaknesses.
A strong recommendation would combine renewable sources such as solar and wind with energy storage or another reliable low-carbon source. This mix can reduce greenhouse gas emissions while improving reliability because different sources can produce electricity at different times. - 15
Use the life cycle diagram to explain why a renewable energy source can still have some environmental impact even if it does not burn fuel during operation.
A renewable energy source can still have environmental impacts from mining raw materials, manufacturing equipment, transporting parts, building the facility, and disposing of or recycling materials. These life cycle impacts are usually different from the direct emissions caused by burning fossil fuels.