Science Physics Grade 10: Sources of Energy Renewable and Non-Renewable

Study Guide: Sources of Energy – Renewable and Non-renewable Grade 10 – Physics (NGSS-aligned)

1. The Driving Question

"If the sun, wind, and rivers never run out, why do we still burn coal and oil to power our homes—and what happens when those fuels finally disappear? How do we decide which energy source to use when each one has trade-offs, like cost, pollution, or reliability?"

2. The Core Idea – Built, Not Listed

Imagine your phone battery. It stores energy, but once it’s empty, you plug it in to recharge. Now scale that up to a whole city. Non-renewable energy sources (like coal, oil, and natural gas) are like a phone with a finite battery—once we burn them, they’re gone, and it takes millions of years to "recharge" (form new fossil fuels). Renewable energy sources (like solar, wind, and hydropower) are like a phone that recharges while you use it—the sun keeps shining, the wind keeps blowing, and rivers keep flowing, so we can keep tapping into them without running out.

But here’s the catch: just like your phone might die on a cloudy day if it’s solar-powered, renewables aren’t always reliable. And just like a phone charger might cost more upfront, some energy sources are cheap to use but expensive (or dangerous) in other ways—like pollution or geopolitical conflicts over oil. The puzzle isn’t just "which energy never runs out?" but "how do we balance what’s available, what’s affordable, and what’s sustainable for the planet?"

Key Vocabulary: - Non-renewable energy Definition: Energy sources that exist in limited quantities and cannot be replaced on a human timescale. Example: The natural gas used to heat homes in Boston comes from underground deposits formed from ancient marine organisms—once burned, it’s gone. College note: In geology, "non-renewable" is debated—some argue nuclear fuel (uranium) is technically renewable on cosmic timescales, but it’s still treated as finite in energy policy.

• Renewable energy Definition: Energy sources that are naturally replenished on a human timescale and are virtually inexhaustible. Example: The Hoover Dam generates electricity from the Colorado River’s flow—even after 80 years, the river still powers Las Vegas because snowmelt keeps it running. College note: "Renewable"-"sustainable." Large hydropower dams can disrupt ecosystems, and biomass (like corn ethanol) can compete with food production.

• Energy density Definition: The amount of energy stored in a given volume or mass of a fuel. Example: A gallon of gasoline (non-renewable) can power a car for 30 miles, while a lithium-ion battery (renewable storage) of the same size might only power it for 5 miles. College note: Energy density is critical in engineering—batteries for electric planes need much higher density than car batteries to be practical.

• Carbon footprint Definition: The total amount of greenhouse gases (like CO?) emitted directly or indirectly by an energy source. Example: Charging your phone with electricity from a coal plant in West Virginia has a higher carbon footprint than charging it with solar power in Arizona. College note: Life-cycle analysis (LCA) expands this—solar panels have a footprint from manufacturing, but it’s still far lower than fossil fuels over their lifetime.

3. Assessment Translation

How this appears on state assessments (e.g., NGSS-aligned tests like the MCAS or Smarter Balanced): - Multiple choice: Questions test trade-offs (e.g., "Which is a disadvantage of solar energy compared to coal?") with distractors that mix up cost, reliability, and environmental impact. Distractor pattern: Wrong answers often confuse renewability with reliability (e.g., "solar is unreliable because it’s renewable"). - Short constructed response: "Explain one advantage and one disadvantage of using wind energy instead of natural gas. Use evidence from the data table below." Proficient response: Names a specific advantage (e.g., "wind emits no CO? during operation") and disadvantage (e.g., "wind turbines require large land areas and can harm bird populations"), then cites numbers from the table. - Evidence-based argument: "A town is deciding whether to build a coal plant or a solar farm. Write a paragraph arguing for one option, using at least two pieces of evidence about cost, reliability, or environmental impact." Proficient response: Takes a clear stance, uses data (e.g., "solar costs $0.06/kWh vs. coal’s $0.10/kWh"), and addresses a counterargument (e.g., "while solar is intermittent, battery storage can mitigate this").

Model Proficient Response (Short Constructed Response): Prompt: "Compare the carbon footprints of coal and hydropower. Which would you recommend for a city aiming to reduce emissions, and why?" Response: "Coal has a high carbon footprint because burning it releases CO?—about 2.2 pounds per kWh. Hydropower, like the Hoover Dam, emits almost no CO? during operation, though building dams can disrupt ecosystems. For a city reducing emissions, hydropower is the better choice because its footprint is 90% lower than coal’s over its lifetime. However, the city should also consider if local rivers can support dams without harming fish populations."

4. Mistake Taxonomy

Mistake 1: Confusing "renewable" with "clean" - Prompt: "Which energy source is both renewable and has no environmental impact?" - Common wrong answer: "Solar power" (students assume "renewable" = "no impact"). - Why it loses credit: Solar panels require mining for materials (e.g., silicon, rare metals) and can disrupt desert ecosystems. "No impact" is a myth—every energy source has trade-offs. - Correct approach: Acknowledge that all energy sources have some impact, then compare the scale (e.g., "solar’s impact is far lower than coal’s, but not zero").

Mistake 2: Ignoring energy density in comparisons - Prompt: "Why do most cars still use gasoline instead of batteries?" - Common wrong answer: "Because batteries are too expensive" (true, but misses the bigger issue). - Why it loses credit: Gasoline has much higher energy density—1 gallon stores ~33 kWh, while a Tesla battery of the same size stores ~0.3 kWh. Even if batteries were free, they’d need to be 100x larger to match gasoline’s range. - Correct approach: Compare energy density first, then discuss cost and infrastructure (e.g., "gasoline’s high density makes it practical for long trips, but batteries are improving").

Mistake 3: Overgeneralizing reliability - Prompt: "Explain why wind energy is less reliable than natural gas." - Common wrong answer: "Because wind doesn’t blow all the time" (true, but incomplete). - Why it loses credit: Reliability isn’t just about availability—it’s about predictability and storage. Natural gas plants can ramp up quickly when demand spikes, while wind requires backup (e.g., batteries or gas plants) to fill gaps. - Correct approach: Define reliability as "meeting demand consistently," then discuss solutions (e.g., "wind farms pair with battery storage to smooth out gaps").

5. Connection Layer

• Within physics: Energy sources-thermodynamics — The laws of thermodynamics explain why no energy source is 100% efficient (e.g., coal plants lose 60% of energy as waste heat, solar panels convert only ~20% of sunlight to electricity).

• Across subjects: Energy trade-offs-economics (supply and demand) — The "duck curve" in California shows how solar power’s midday surplus crashes electricity prices, forcing gas plants to ramp up quickly at sunset—a real-world example of how physics and economics collide.

• Outside school: Carbon footprints-your phone’s battery life — The lithium in your phone’s battery is mined in places like the Democratic Republic of Congo, where child labor and environmental damage are major issues. Renewable energy storage (like grid batteries) faces the same ethical dilemmas.

6. The Stretch Question

"If a country could only use one energy source for the next 50 years, which should it choose—and why isn’t the answer as simple as ‘solar’ or ‘nuclear’?"

Pointer toward the answer: The "best" choice depends on the country’s geography, economy, and priorities. For example: - Iceland (volcanic, small population) could rely 100% on geothermal and hydropower. - Germany (cloudy, industrial) might choose wind + nuclear to balance reliability and emissions. - Saudi Arabia (sunny, oil-rich) could transition to solar but would need massive storage to handle nighttime demand. The real answer isn’t a single source—it’s a mix tailored to local conditions, with trade-offs in cost, land use, and politics. (And yes, this is why energy policy is so contentious!)