Suggested audience: middle-school learners, approximately ages 11+ with adult support. Time: one 40–50 minute class, or two short sessions. Prerequisites: multiplication, decimals and the distinction between instantaneous power and accumulated energy.
Materials: a browser with Renewable Energy City, this printed worksheet or a notebook, and an optional calculator. No login or student names are required. The simulation is a fictional five-minute energy-accounting model, not real electrical design software.
Learning objectives: distinguish kW from kWh, compare variable solar/wind generation against requested load, identify battery storage and power-conversion limits, find the first unserved demand and evaluate one controlled design improvement.
Student challenge: Can Blackout Island stay powered?
Predict → Build → Measure → Change one thing → Explain. In the game, choose one challenge, predict when the first shortage will happen, build with the available fictional credits, then run the full scenario.
Know the units: kW is power at a moment; kWh is energy over time. One five-minute interval is 0.0833 hour (1/12 hour). A 1 kW load for five minutes uses about 0.083 kWh; an uninterrupted 1 kW load for one hour uses 1 kWh.
1. Choose a mission and predict
- 01 · First Lights: 24 simulated hours; 2400 fictional credits; starting battery charge 0%. Power Blackout Island for one sunny day.
- 02 · Through the Night: 24 simulated hours; 2800 fictional credits; starting battery charge 50%. Keep homes and the school supplied through the night.
- 03 · Two Cloudy Days: 48 simulated hours; 3700 fictional credits; starting battery charge 50%. Survive cloudy weather and an evening wind lull.
My mission: ____________________________________
Prediction: Will all requested power be served? When could the first shortage occur? ______________________________
2. Build and record evidence
The simulation defines each solar array as 1 kW • makes electricity by day, each wind turbine as 1 kW • output depends on wind, and each battery as 4 kWh • stores energy • 1 kW charge/discharge. These are fictional ratings. Record the actual battery energy at the start, not merely the number of batteries.
| What I recorded | Value | Unit |
|---|---|---|
| Solar arrays / wind turbines / batteries | ____ / ____ / ____ | number |
| Solar / wind rated total | ________ | kW |
| Total internal battery capacity | ________ | kWh |
| Starting stored battery energy | ________ | kWh |
| First shortage (or none) | ________ | day and clock time |
| Total requested / served / unserved | ____ / ____ / ____ | kWh |
3. Improve just one design variable
Keep the mission, weather, community loads and time period unchanged. Change one asset count, or replace one asset, within the mission budget. Write down the change and rerun. Be aware that adding batteries also increases starting stored energy in missions that start partially charged; it is not a storage-only comparison unless you account for that difference.
Exactly what did I change? ______________________________________________________________
| Metric | Original run | Revised run | Unit |
|---|---|---|---|
| Initial stored battery energy | kWh | ||
| Unserved requested energy | kWh | ||
| First shortage | time / none | ||
| Fictional credits spent | credits |
4. Explain and reflect
At the first shortage, was the main problem (a) not enough renewable generation, (b) not enough stored energy, (c) a battery discharge power limit, (d) the 4 kW AC converter limit, or (e) the all-or-nothing pump load? Use the game's recorded causes and compare actual kW available to kW requested; several constraints can matter together.
Explain why your revision helped or failed, using one kW measurement and one kWh measurement. What would be different if the weather, starting battery charge or community demand changed?
Open the interactive city experiment · Read the model and assumptions
Facilitator guidance — not printed with student worksheet
Teaching sequence: 5 minutes introduce kW/kWh; 5 minutes predict; 15 minutes build, run and inspect the timeline; 10 minutes change one design variable and compare; 5–10 minutes discuss what the recorded evidence permits you to conclude. Avoid grading by a single fixed winning design.
Expected reasoning: sunlight follows a simplified daytime curve; after sunset, solar output is zero. Batteries shift energy between intervals but cannot create it. Each bank has 4 kWh internal capacity and 1 kW charge and discharge limits; it may have stored kWh remaining yet be unable to provide enough instantaneous kW. The shared AC converter has a 4 kW ceiling and is 95% efficient. Charge and discharge efficiencies are also 95% each. Unserved demand can stem from more than one model constraint.
First Lights special case: its starting battery fraction is 0% and the scenario begins at 08:00. Other authored challenges begin at 06:00 with 50% of installed battery capacity stored at the start. Students who add batteries in these later scenarios are changing both storage capacity and initially stored kWh; ask them to record both.
Reading results: the simulated DC bus combines solar and wind. The engine accounts in five-minute intervals (0.08333333333333333 h) with a 95%-efficient AC conversion step. A scheduled 0.4 kW pump must be fully supplied for the entire step or not supplied; homes and school may be served partially. Look at the timeline and requested/served totals rather than inferring a guaranteed first-shortage time from a hypothetical design.
Fair comparisons: use the same mission, initial-charge rule, weather, demand, duration and unchanged equipment except for the explicitly tested variable. A successful revision can sometimes be caused partly by increased initial stored energy. Ask learners what can and cannot be attributed to the changed asset.
Common misconceptions: kW and kWh are not interchangeable; a full battery does not eliminate its discharge power limit; no electricity is created when stored energy is discharged; 4 kW is an instantaneous output cap, not a 4 kWh battery; a visual panel moved to another construction plot does not gain different irradiance. Fictional prices and asset ratings are not real products.
Safety and provenance: the deterministic rules and operating boundaries come from the published methodology. No live location weather, site-specific wiring, protection, surge current, battery aging or code review is modeled. Do not convert game outcomes into physical installation advice. The worksheet requires no identifying information.