Which energy sources run out, and which keep being replenished?
Topic 6.1 Renewable and Nonrenewable Resources: distinguish renewable from nonrenewable energy resources and explain why the distinction matters for sustainability.
A focused answer to APES Topic 6.1, covering the difference between renewable and nonrenewable energy resources, examples of each, the idea of potentially renewable resources, and why the distinction matters for sustainability, with a worked depletion calculation.
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What this topic is asking
The College Board (Topic 6.1) wants you to distinguish renewable from nonrenewable energy resources, give examples of each, and explain why the distinction matters for sustainability.
Renewable versus nonrenewable
The fossil fuels (coal, oil, natural gas) formed over hundreds of millions of years from buried organic matter, so on any human timescale the supply is fixed. Uranium for nuclear fission is also nonrenewable. By contrast, the Sun delivers energy continuously, the wind blows, rivers flow and Earth's interior stays hot, so solar, wind, hydro and geothermal can be tapped indefinitely.
Potentially renewable resources
Why this matters
The renewable versus nonrenewable split underlies the whole of Unit 6. A society built on fossil fuels is drawing down a fixed account and faces eventual depletion plus the climate consequences of Unit 9; a society built on renewables can in principle sustain itself. This is the energy face of sustainability: living on the interest (renewable flows) rather than the capital (nonrenewable stocks).
Try this
Q1. Identify two renewable energy resources. [1 point]
- Cue. Any two of solar, wind, hydroelectric, geothermal, biomass, tidal.
Q2. Explain why groundwater can be described as potentially renewable. [2 points]
- Cue. Groundwater is recharged naturally by infiltration, so it can renew; but if it is pumped out faster than it recharges, the aquifer is depleted and it behaves like a nonrenewable resource.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2021 (style)4 marksSection II (FRQ). (a) Define a renewable energy resource. (b) Identify two nonrenewable energy resources. (c) Explain why fossil fuels are classified as nonrenewable. (d) Describe one reason a potentially renewable resource such as wood can become effectively nonrenewable.Show worked answer →
A 4-point FRQ on the renewable versus nonrenewable distinction.
(a) Define (1 point): a renewable resource is replenished by natural processes at a rate equal to or faster than it is used (for example solar, wind, hydro).
(b) Identify (1 point): any two of coal, oil, natural gas, or uranium (nuclear).
(c) Explain (1 point): fossil fuels form over millions of years from buried organic matter, so they are used far faster than they regenerate, making the supply effectively fixed.
(d) Describe (1 point): a potentially renewable resource such as wood becomes effectively nonrenewable if it is harvested faster than it regrows (deforestation outpacing replanting).
Markers reward the rate-of-replenishment definition, two correct nonrenewable examples, the million-year formation timescale, and the over-harvesting point for the potentially renewable case.
AP 2019 (style)1 marksSection I (multiple choice). Which of the following is a nonrenewable energy resource? (A) Wind (B) Geothermal (C) Natural gas (D) Solar. Justify your choice.Show worked answer →
A 1-point MCQ on resource classification. The answer is (C).
Natural gas is a fossil fuel formed over millions of years, so it is depleted far faster than it forms and is nonrenewable. Wind (A), geothermal (B) and solar (D) are all renewable, replenished continuously by the Sun or by Earth's internal heat. The trap is assuming any underground resource is renewable; what matters is the rate of replenishment relative to use.
Related dot points
- Topic 6.5 Fossil Fuels: explain how fossil fuels form and are used to generate electricity, and describe their environmental impacts, including cogeneration.
A focused answer to APES Topic 6.5, covering how fossil fuels form, how a fossil-fuel power plant generates electricity, fracking, cogeneration, and the environmental impacts of coal, oil and gas, with a worked power plant efficiency calculation.
- Topic 6.2 Global Energy Consumption: describe patterns of global energy use and the factors, including development and population, that drive demand.
A focused answer to APES Topic 6.2, covering global patterns of energy consumption, the dominance of fossil fuels, differences between more and less developed countries, the drivers of demand (population, economic development, lifestyle), and a worked per capita energy calculation.
- Topic 6.8 Solar Energy: describe how solar energy is captured using photovoltaic, active and passive systems and evaluate its benefits and drawbacks.
A focused answer to APES Topic 6.8, covering photovoltaic cells, active and passive solar heating, the benefits (renewable, low emissions) and drawbacks (intermittency, land, cost) of solar energy, and a worked photovoltaic output calculation.
- Topic 5.12 Introduction to Sustainability: define sustainability and sustainable yield, and explain the indicators used to assess whether resource use is sustainable.
A focused answer to APES Topic 5.12, covering sustainability, sustainable yield, the difference between renewable and non-renewable resources, indicators of sustainability (biodiversity, soil, water, productivity), and the link to natural capital, with a worked sustainable-yield calculation.
- Topic 5.11 Ecological Footprints: define the ecological footprint, explain what it measures, and compare footprints between countries and lifestyles.
A focused answer to APES Topic 5.11, covering the ecological footprint, what it measures, the factors that raise or lower it, biocapacity and overshoot, comparison between countries, and how to interpret footprint data, with a worked footprint calculation.
Sources & how we know this
- AP Environmental Science Course and Exam Description — College Board (2020)