Skip to main content
Back to Earth and Space

FIELD STATION · RESOURCES & HUMAN IMPACT

Earth Resources & Human Impact Lab

File ▾

CHOOSE YOUR INVESTIGATION LEVEL

What does it cost to use Earth’s resources?

Both levels use the same model: forest and ore stocks year by year, power projects’ energy return and life-cycle emissions, ore grade and land, and a town’s electricity use. AP adds capacity limits, net energy, residual ore, the emissions from mine electricity and before/after ratios.

About this model

Two kinds of number. The life-cycle emission factors are real: the median values from NREL’s 2021 review of life-cycle greenhouse-gas studies (solar PV 43, wind 13, natural gas 486, nuclear 13 g CO₂e per kWh). On screen they sit in solid cards marked 📖 SOURCED. Everything else is hypothetical: forest and seam tonnes, demand, regrowth, project energies, ore grade, recovery, electricity per tonne, land areas and the town. Those sit in dashed, hatched cards marked HYPOTHETICAL. They are made-up teaching values, not data from a real forest, mine or power plant.

Stocks. Each year: growth = the smaller of the regrowth and the room left under the capacity; then the harvest = the smaller of the demand and the stock available; unmet demand = demand − harvest. The stock can never go below zero. The ore/fuel seam has zero regrowth on this timescale. Mined material is moved, not destroyed. Real forests regrow in a more complicated way (slow when sparse, slow again when crowded, years of delay after cutting), and real supplies respond to prices and new discoveries; this model leaves all of that out.

Energy return. EROI = lifetime energy delivered ÷ lifetime energy invested, in the same units and boundaries (Weißbach et al. definition). Net energy = delivered − invested. The animation draws all invested energy up front; really, fuel and upkeep are spent during operation too. The project energies are made up, so this lab never ranks real technologies by EROI and sets no “worth it” threshold. Allocated life-cycle emissions = MWh × 1000 kWh/MWh × g/kWh ÷ 1 000 000 g/t: they are shared out over every kWh delivered, not released at the moment you see them.

Mining. Recovered metal = ore × grade × recovery. Residual processed ore = ore − recovered metal. That leaves out overburden (rock moved to reach the ore), added chemicals, by-products and toxicity. Electricity used = ore × kWh per tonne (hypothetical). Land allocation cannot use more land than the site has; the lab never scores which land use is “better”: that needs evidence about the place and the people.

People. Total electricity = population × kWh per person per year; CO₂e = that × the source’s life-cycle intensity. This is only electricity accounting. It is not a full environmental-impact equation and it does not show what causes population or consumption to change.

Randomness. Nothing in the model is random. “New scenario” uses Codex’s seeded generator, and the seed is shown so a scenario can be repeated exactly. Tests draw their questions with a seed per attempt.

NREL 2021 fact sheet NREL/FS-6A50-80580, “Life Cycle Greenhouse Gas Emissions from Electricity Generation: Update” (NREL life-cycle emissions factors dataset) · Weißbach et al.: EROI definition · USGS: copper statistics · EIA: renewable energy sources · Ehrlich & Holdren 1971: impact of population growth

What am I looking at?

How the lab works. Pick Explore or one lab at the top. Each lab has five tabs: Pre-lab, Bench, Data & graph, Claim · Evidence · Reasoning, and Test. On the Bench, the coach lists your steps; they tick themselves as you work. Press What do I do now? when you’re stuck.

Solid cards marked 📖 SOURCED hold real published numbers (life-cycle emissions). Dashed, hatched cards marked HYPOTHETICAL hold made-up numbers you or the scenario set.

① Stocks. Left: a managed forest (renewable; regrowth up to the dashed “cap” line). Right: an ore or fuel seam in layered rock (nonrenewable; no regrowth). Both face the same demand. Each year has three beats: ① growth (saplings, “+”), ② harvest (logs to the woodpile, lumps up the shaft to the stockpile), ③ unmet demand (red hatched ✗ bar). The ledger under each scene adds it up. Tap a panel to choose which stock the record buttons use.

② Energy. A power project. Orange particles: energy invested to build it (IN). Blue particles: energy it delivers over its life (OUT). The slate blocks are life-cycle CO₂e, shared out per kWh delivered.

③ Mine & land. Orange specks in the ore body show the grade. The truck hauls ore to the mill; copper ingots (1 ingot = 100 t) and the pale residual pile come out. Pile size grows with mass (volume ∝ tonnes). Right: the land plan in ½ km² tiles: brown terraces = mine, green rows = other uses, pale dotted = land left.

④ People. One house = 2,000 people; more lit windows = more electricity per person.

Keys: Space play / pause · → step one beat · R reset · Z / X zoom.