Energy, Water & Material Resources — Print · Physics & Environmental Science, Grade 12

Nonrenewable Energy & Fossil Fuels

Learning goals

• I can describe how coal, oil, and natural gas form and how they are extracted.
• I can explain the environmental and climate consequences of burning fossil fuels.
• I can compare the benefits and drawbacks of nuclear power against those of fossil fuels.

Readings for this unit

• Compare the service rather than the label on the technology

Coal, petroleum, natural gas, and mined nuclear fuels are treated as nonrenewable on human planning timescales. Fossil fuels store chemical energy in carbon-containing material formed over geological time. Nuclear fuels release energy by changes in nuclei; they are not fossil fuels.

Burning fossil fuels produces heat that may drive a turbine and generator or provide direct heating. Combustion emissions include CO₂ and may include particles, nitrogen oxides, and sulfur compounds depending on fuel and controls. Energy density, infrastructure, and operating flexibility influence use.

Fossil-fuel formation depends on organic source, burial history, heat, time, and geology. Coal often develops from plant-rich deposits; petroleum and gas have varied source and maturation pathways. Depth alone is not a sufficient universal predictor of oil versus gas.

Nuclear fission can supply heat for a turbine without direct CO₂ from carbon combustion. Mining, fuel processing, construction, and decommissioning still have life-cycle impacts; nuclear is not literally carbon-free across every boundary. Radioactive waste and long-term management require separate accounting.

Compare equal delivered energy with stated emission factors. If a supplied model uses coal 2.2lbCO₂/kWh and gas.9lbCO₂/kWh, replacing 1000 kWh gives a modeled reduction 1300lb. Those are practice factors, not universal current plant values or a full life-cycle comparison.

A resource decision should consider reliability, extraction impacts, climate emissions, other pollution, water use, cost, waste, and affected communities. Distinguish established mechanisms from locally variable numerical assumptions and do not choose solely from one bar-chart value.

Model check: Low direct operational CO₂ does not mean zero life-cycle impacts.

CO2 Avoided by Switching Fuels

CO2 avoided = electricity (kWh) x (emission factor of old fuel - emission factor of new fuel)

the emission factor is the pounds of CO2 released per kWh for each fuel (for example, coal is about 2.2 lb/kWh and natural gas about 0.9 lb/kWh); the difference times the electricity generated gives the CO2 saved by switching.

Worked examples

Avoid these mistakes

• Low direct operational CO₂ does not mean zero life-cycle impacts.

Words to know

fossil fuel

A nonrenewable energy resource — coal, oil, or natural gas — formed from the buried remains of ancient organisms transformed by heat and pressure over millions of years.

combustion

The chemical reaction of burning a fuel with oxygen, releasing the fuel's stored chemical energy as heat and light and producing carbon dioxide and other emissions.

hydraulic fracturing (fracking)

A drilling method that injects high-pressure fluid underground to crack open shale rock and release the oil or natural gas trapped inside it.

nuclear fission

The splitting of a heavy atomic nucleus (such as uranium-235) into smaller nuclei, releasing a large amount of energy that a power plant uses to make steam and generate electricity.

In the real world

Compare supplied direct-operation and life-cycle factors separately when evaluating equal delivered energy.

Exit check

Compare fossil-fuel and nuclear electricity mechanisms.

Renewable Energy

Learning goals

• I can describe how solar, wind, hydroelectric, geothermal, and biomass energy generate power.
• I can evaluate the benefits and trade-offs of each renewable energy source.
• I can explain what intermittency means and why energy storage is central to a renewable grid.

Readings for this unit

• Compare the service rather than the label on the technology

Renewable energy draws on replenishing processes such as sunlight, wind, flowing water, geothermal heat, and biomass growth. Replenishment does not imply unlimited local extraction or no environmental impacts. Biomass harvest can exceed regrowth, and water or geothermal use can affect the supporting system. Compare useful output, timing, materials, land, water, and lifecycle effects under the proposed conditions.

Photovoltaic cells convert incident light into electrical output without combustion at the panel. Output varies with irradiance, temperature, orientation, and device conditions; clouds often reduce output rather than making it universally zero. No sunlight at night requires another delivery source or stored energy. Manufacturing, transport, infrastructure, and end-of-life stages contribute to a wider environmental account beyond panel operation.

Wind turbines convert the kinetic energy of moving air into electricity, and thanks to steady improvements they are now among the cheapest sources of new power anywhere. Wind emits nothing as it runs, and the land beneath a turbine can still be farmed or grazed. The trade-offs: wind is intermittent (it blows when it blows, not when you need it), turbines can kill birds and bats, some people object to their look and noise, and the best winds are often offshore or in remote regions far from cities. Hydroelectric power, by contrast, is wonderfully controllable — a dam can release water to make electricity on demand — but building the dam floods large areas of land, blocks fish migration, traps sediment, and permanently reshapes a river.

Geothermal energy taps the natural heat of Earth's interior, using hot water or steam from underground to spin turbines or warm buildings directly. Because that heat never stops flowing, geothermal runs steadily around the clock with a small surface footprint — but it is largely limited to geologically active regions like Iceland or the western United States, where the heat is close enough to the surface to reach affordably. Biomass means burning plant matter or waste — wood, crop residue, or biogas — or refining crops into liquid biofuels like ethanol. Biomass is sometimes called 'carbon-neutral' because the plants absorbed CO2 as they grew, so regrowing them can reabsorb what burning releases. But that only holds if the plants are genuinely replaced, burning still produces air pollution, and growing fuel crops can compete with food and clear forests.

Nameplate capacity and actual generated energy are different quantities. Capacity factor is actual energy over an interval divided by the energy that continuous nameplate output would provide during that interval. It is not simply the fraction of time a source runs at full output and is not conversion efficiency. Dispatchability describes the ability to control delivery under operating constraints; hydrological, fuel, equipment, and other limits still matter.

And planning around intermittency is the central engineering challenge of a renewable future. When the wind dies down at dinnertime or clouds roll over a solar farm, the grid still has to keep the lights on. The answer is energy storage — grid-scale batteries, or clever tricks like pumping water uphill to release later — together with smarter grids that shift and share power across wide regions. Renewables are a powerful technological solution for reducing human impact on the climate and on finite fuel supplies, but realizing that promise depends less on the panels and turbines themselves than on solving the storage-and-timing puzzle around them.

Model check: Renewable describes replenishment, not zero impact or unlimited site availability. 12/(2×24)=.25=25%; it is not conversion efficiency.

Capacity Factor

capacity factor = average actual output / maximum (nameplate) capacity

the result is written as a fraction or percent; steady sources like geothermal have high capacity factors, while intermittent solar and wind have lower ones because they only produce power when the sun shines or wind blows. Rearranged, average output = nameplate capacity x capacity factor.

Worked examples

Avoid these mistakes

• Renewable describes replenishment, not zero impact or unlimited site availability.

Words to know

renewable energy

Energy drawn from sources that nature replenishes on a human timescale — sunlight, wind, flowing water, Earth's internal heat, and plant matter.

photovoltaic (PV) cell

A device, usually made of silicon, that converts sunlight directly into electricity.

intermittency

The tendency of some renewable sources — especially solar and wind — to produce power only when the sun is shining or the wind is blowing, rather than on demand.

capacity factor

The fraction of the time a power source actually delivers its maximum possible output, written as a percent; intermittent sources have lower capacity factors than steady ones.

How much sunlight? Far more than we could ever use

The scale of the solar resource is hard to overstate. The Sun bathes the Earth in roughly 173,000 terawatts of power continuously, while all of human civilization uses on the order of just 18 terawatts. Put another way, enough sunlight strikes the Earth in a single hour to power everything humanity does for an entire year. The challenge of solar energy, then, has never really been quantity — it is capturing that diffuse, on-and-off energy affordably and storing it for when the Sun isn't shining. Every advance in cheaper panels and better batteries chips away at that engineering puzzle rather than at any shortage of sunlight.

The duck curve: when too much solar becomes its own problem

Grid operators in sunny places like California watch a graph nicknamed the duck curve. As rooftop and utility solar flood the grid at midday, the net demand that other power plants must meet sags into the shape of a duck's belly — then, as the sun sets and people arrive home and switch everything on, demand shoots up the duck's 'neck' in just a few hours. Meeting that steep evening ramp without cheap storage forces operators to fire up fast, often gas-burning, 'peaker' plants. The duck curve is a vivid reminder that a renewable grid's hardest problem is timing, not total energy.

Not all 'green' is equal: the trade-offs of dams and biofuels

It is tempting to treat 'renewable' as a synonym for 'harmless,' but the two are not the same. Large hydroelectric dams flood whole valleys and ecosystems, block fish migrations, and — surprisingly — can emit significant methane as drowned vegetation rots in the reservoir. Corn ethanol, a common biofuel, can take nearly as much fossil energy to grow, fertilize, and distill as it ultimately delivers, and growing fuel crops competes with growing food. The lesson is that 'renewable' describes where the energy comes from, while 'sustainable' describes whether we can keep doing it without serious harm — and a source can be one without fully being the other.

Pumped hydro: the world's biggest battery is made of water

When people picture grid storage they think of giant lithium batteries, but by far the most energy stored on the world's grids today sits in pumped-storage hydropower. The idea is elegantly simple: when electricity is cheap and plentiful, surplus power pumps water uphill into a high reservoir; when demand spikes, that water is released back down through turbines to regenerate electricity, at round-trip efficiencies near 80%. New York runs exactly such a plant — the Blenheim-Gilboa pumped-storage project in the Catskills — which acts like a huge rechargeable battery for the regional grid, smoothing out the peaks and valleys of demand.

New York's offshore wind bet

New York has committed by law to getting 70% of its electricity from renewables by 2030 and to building 9,000 megawatts of offshore wind by 2035. That target moved from paper to reality when South Fork Wind, off the eastern tip of Long Island, delivered its first power in late 2023 as one of the first utility-scale offshore wind farms in the United States. Offshore wind is attractive for a densely populated coastal state because ocean winds are strong and steady and the turbines sit far from most neighborhoods — though the projects still must navigate costs, fishing interests, and effects on marine life, the familiar trade-offs of any real energy choice.

In the real world

New York's plan to power the state largely with offshore wind farms off Long Island and big upstate solar arrays is a real-world bet on renewables — and on solving their intermittency with grid-scale batteries.

Exit check

A2 kW turbine produces 12 kWh in 24h. Find capacity factor.

Water & Land Resources

Learning goals

• I can explain why usable freshwater is a small and unevenly distributed fraction of Earth's water.
• I can describe how a watershed collects water and why protecting it protects the water supply.
• I can analyze how land use and agriculture affect water and soil resources.

Readings for this unit

• Compare the service rather than the label on the technology

A watershed is the land draining toward a common outlet. Water availability depends on precipitation, storage, surface flow, groundwater, quality, infrastructure, and timing. Freshwater percentage alone does not establish what is locally safe or accessible.

Much of Earth’s freshwater is in ice or groundwater rather than easily collected lakes and rivers. This course uses rounded distribution models for fraction practice; categories and accessibility definitions must be stated. Do not confuse a percentage of freshwater with the same percentage of all water.

Withdrawal is water removed from a source; consumption is the part not promptly returned to that same system. Agriculture, industry, and domestic shares vary by place, year, and definition. In a stated practice allocation 70% agricultural,20% industrial, the remainder is 10%; treat it as supplied data.

Irrigation can support crops but can deplete storage when withdrawals exceed recharge. Evaporation can concentrate salts and drainage can transport nutrients. Improved irrigation efficiency does not always lower total basin consumption if planted area or production expands; evaluate the larger boundary.

Land use changes infiltration, runoff, habitat, erosion, and water quality. Impervious surfaces can accelerate runoff, while vegetation and soil structure can retain water and filter some pollutants. A measure that works at one scale may have downstream consequences.

Use a water budget: storage change equals inputs minus outputs for a defined place and period. Compare conservation, reuse, treatment, and land-management options using measurements, seasonal reliability, ecological flow needs, and distribution of costs and benefits.

Model check: Water withdrawn can partly return; consumption is the portion not promptly returned to the same system.

Worked examples

Avoid these mistakes

• Water withdrawn can partly return; consumption is the portion not promptly returned to the same system.

Words to know

freshwater

Water with very little dissolved salt, usable for drinking and agriculture; it makes up only a small fraction of all the water on Earth.

watershed

The entire area of land where all the water that falls on it drains to a common outlet, such as a river, lake, or bay.

aquifer

An underground layer of rock or sediment that holds and transmits groundwater, which can be pumped up through wells.

irrigation

Supplying water to crops artificially through channels, sprinklers, or drip systems; it is the single largest human use of freshwater.

In the real world

Farmers in California's Central Valley irrigating crops during drought must weigh bigger harvests against draining the rivers and aquifers they share — a real, high-stakes water-resource trade-off.

Exit check

A model allocates 70% farming and 20% industry. What remains?

Mineral & Soil Resources

Learning goals

• I can explain how mineral ores form and how they are extracted by mining.
• I can describe how soil forms slowly and how it becomes degraded.
• I can identify practices that conserve soil and mineral resources.

Readings for this unit

• Compare the service rather than the label on the technology

Look around any room and nearly every hard object traces back to the ground: the copper wiring in the walls, the aluminum in a can, the lithium in a phone battery, the steel in a bike frame. All of it began as an ore — a rock deposit rich enough in a valuable mineral to be worth mining. Like fossil fuels, metal ores are nonrenewable and unevenly distributed, and for the same reason: their locations are fingerprints of specific ancient geologic processes. Hot, mineral-rich fluids, cooling magma, and long weathering each concentrate different metals in particular places, which is why some regions are rich in copper or gold and others have almost none.

Surface and underground mining access deposits under different geological and operating conditions. Overburden, waste rock, and tailings are distinct streams: tailings are residues after ore processing, not a name for all excavated rock. Exposed sulfide minerals can contribute to acid drainage and dissolved-metal transport under suitable conditions. Evaluate extraction, processing, water, habitat, residual management, and long-term monitoring within a clearly stated boundary.

Now consider a resource so ordinary we walk on it and call it 'dirt' — yet it may be the most quietly essential of all: soil. Good soil is not lifeless dust but a living mixture of weathered rock, decayed organic matter (called humus), water, air, and countless organisms. It forms in distinct soil horizons that stack into a soil profile: a thin surface layer of litter (the O horizon), the dark, fertile topsoil (A horizon) where most plant roots live, a mineral-rich subsoil (B horizon), and weathered parent rock below (C horizon), all resting on solid bedrock. That topsoil is the layer that grows nearly all of humanity's food.

Here's the catch that makes soil a resource worth guarding: it forms agonizingly slowly. Nature may take hundreds of years to build a single inch of topsoil from weathering rock and decaying life. Technically that makes soil renewable — it does regenerate — but it regenerates so slowly compared to how fast we can lose it that, in human terms, we treat it much like a nonrenewable resource. Once fertile topsoil is stripped away, the land's ability to grow food can be lost for generations, no matter how the geology classifies it.

And soil is being lost — a process called soil degradation. The biggest culprit is erosion by wind and water, which speeds up dramatically when plowing, deforestation, or overgrazing strips away the plants whose roots hold soil in place. The American Dust Bowl of the 1930 s is the classic warning: farmers plowed up the deep-rooted prairie grasses of the Great Plains, and when drought struck, the bare topsoil simply blew away in enormous 'black blizzards.' Degradation also comes from salinization (from over-irrigation), nutrient depletion (from growing the same crop endlessly), and compaction — each one chipping away at the thin, fertile layer we depend on.

The response, as always in this unit, is conservation — and for soil there's a well-stocked toolkit. Contour plowing and terracing slow water running downhill; cover crops, crop rotation, and no-till farming keep roots in the ground and the surface covered year-round; windbreaks of trees blunt erosive winds. For minerals, conservation means using less, recycling metals (recycling aluminum uses only about 5% of the energy needed to make it from fresh ore), and reclamation — restoring mined land once extraction ends. Both stories come back to the same cost-benefit reckoning: because ores and topsoil form far slower than we consume them, using them wisely today is what keeps them available tomorrow.

Model check: A mineral reserve is an economically recoverable subset of resources under specified conditions. It may form much more slowly than it erodes; erosion can remove essential productive layers within the planning period.

Soil Loss vs. Formation Rate

times faster soil is lost = (years to form 1 inch) / (years to erode 1 inch)

soil forms very slowly (often hundreds of years per inch) but can erode in decades; a ratio well above 1 means soil is disappearing faster than nature rebuilds it, so it must be conserved like a nonrenewable resource.

Worked examples

Avoid these mistakes

• A mineral reserve is an economically recoverable subset of resources under specified conditions.

Words to know

ore

A rock or mineral deposit that contains enough of a valuable metal or mineral to be worth mining and extracting.

soil horizon

A distinct layer of soil — such as the O, A, B, and C horizons — that differs from the layers above and below it in color, texture, and composition.

soil degradation

The decline in soil quality caused by erosion, loss of nutrients, salinization, compaction, or contamination.

reclamation

Restoring mined or degraded land to a stable, safer, and useful condition after resources have been extracted.

How ore deposits concentrate: hydrothermal veins

Valuable metals are spread thinly through ordinary rock, so a deposit only becomes an ore when some process concentrates the metal enough to be worth mining. A major concentrator is hydrothermal activity: hot, mineral-laden water circulates through cracks deep underground, and as it cools it precipitates metals like gold, silver, and copper into rich veins. Other ores form as heavy minerals settle out of cooling magma, or as slow weathering leaches away everything but the valuable metal near the surface. Because each of these processes only happens in particular geologic settings, ores are patchy — which is exactly why some regions strike it rich while their neighbors have little.

Acid mine drainage: mining's long chemical shadow

Some of mining's worst damage arrives long after the miners leave. When sulfide minerals — common in metal ores — are exposed to air and water by digging, they react to form sulfuric acid, which dissolves toxic metals out of the surrounding rock and carries them into streams. This acid mine drainage can keep poisoning waterways for a century or more, staining creek beds orange and killing aquatic life. Cleaning it up is one of the toughest challenges of land reclamation, and it is a powerful argument for weighing the full, long-term cost of a mine against the short-term value of the metal it yields.

The myth that soil is just lifeless 'dirt'

We use 'dirt' as an insult, but healthy soil is one of the most crowded ecosystems on the planet. A single teaspoon of rich topsoil can contain billions of bacteria along with fungi, protozoa, and other organisms that recycle nutrients, build soil structure, and lock away carbon. This living web is what makes soil fertile in the first place. Treating soil as an inert medium — to be tilled hard, sterilized with chemicals, and left bare — kills that biology and accelerates degradation, which is why modern conservation focuses on feeding and protecting soil life through practices like no-till farming and cover crops.

The 1930 s Dust Bowl: a catastrophe made by land use

The Dust Bowl stands as the starkest lesson in soil science. Through the 1920 s, farmers plowed up millions of acres of the southern Great Plains, tearing out the deep-rooted native grasses that had anchored the soil for thousands of years. When a brutal multi-year drought hit in the 1930 s, the exposed topsoil dried out and blew away in towering 'black blizzards' — some so vast they darkened skies as far east as New York City and Washington, D.C. The disaster ruined farms, drove a mass migration westward, and shocked the nation into creating the federal Soil Conservation Service in 1935 to promote the erosion-fighting practices still used today.

The battery-metal dilemma: mining to fight climate change

The shift to clean energy carries a paradox: building it requires digging up more minerals. Electric-car batteries and grid storage devour lithium, cobalt, and nickel, while wind turbines and electronics rely on rare earth elements — and a single EV battery can contain tens of kilograms of these metals. So the very technologies meant to cut carbon emissions depend on new mines that bring their own land disturbance, water use, and labor concerns, sometimes in countries with weak protections. This tension makes recycling old batteries, designing devices to use less of the scarce metals, and sourcing them responsibly central to whether the clean-energy transition is truly sustainable.

In the real world

The global rush to mine lithium and cobalt for electric-car batteries is a modern mineral-resource dilemma: the very metals that help cut carbon emissions come from mines with their own land and water impacts.

Exit check

Why can soil be effectively nonrenewable on a human planning timescale?

Life-Cycle Energy & Resource Accounting

Learning goals

• I can compare equal service through a defined life-cycle boundary.
• I can calculate break-even use and distinguish capacity factor from efficiency.

Readings for this unit

• Compare the service rather than the label on the technology

A life-cycle assessment compares resource use and impacts from extraction through manufacture, transport, use, and end of life. Define the system boundary and delivered function first. Comparing one disposable item with one reusable item can be misleading if their service differs.

Embodied energy is energy used to produce and deliver a material or device before use. Operational energy is consumed during use. A more efficient device can have higher production impact but save enough in use to lower total impact; a break-even calculation makes assumptions visible.

For an energy device, capacity is a rated maximum power under specified conditions, while energy is actual power integrated over time. Capacity factor equals actual energy divided by rated power times period. It does not measure thermodynamic efficiency; a resource-dependent generator can have low capacity factor without wasting a comparable fraction of its input energy.

Energy return on energy invested, EROI, is energy delivered divided by energy invested within a specified boundary. A value alone is incomplete without method and timescale. Energy quality, timing, reliability, grid needs, and ecological impact are additional considerations.

Recycling can reduce primary extraction but requires collection, transport, and processing. Material contamination and quality loss influence reuse. Resource depletion, water use, greenhouse emissions, habitat impacts, and human consequences may favor different options; combine evidence with explicit decision priorities.

Supply scenarios rather than one universal ranking. Show equations, units, assumptions, uncertainty ranges, and sensitivity to use count or local conditions. A transparent decision can be revisited when better data arrive without changing the physical accounting principles.

Worked examples

Avoid these mistakes

• Do not confuse capacity factor with conversion efficiency.

Words to know

embodied energy

Energy used before a product’s operating life within a stated boundary.

functional unit

The equal service used as a basis for comparison.

capacity factor

Actual energy divided by maximum rated energy over the same interval.

In the real world

Use the chapter investigation to connect this unit to measured evidence and a practical decision.

Exit check

What makes an impact comparison reproducible?