Series: Mining & Materials • Part 7
Mega Vans & Flywheels — Trucks as Rolling Batteries
In our world, trucks don’t burn — they buffer. Each “mega van” is a 200‑ton payload robot with a few megawatt‑hours on board and a flywheel that eats power spikes for breakfast. They make hauling part of the electrical system, not an exception to it.
Today’s mission
Design the truck as an energy device first, a vehicle second.
Publish pre‑calculated routes, pack sizes, and charger power (no JS needed).
Prove that we can mine and build super fast with quiet electrons.
Why trucks as batteries (and why they make the site faster)
We move earth in pulses: load, climb, dump, descend. Batteries hate pulses; flywheels love them. So each truck does two jobs: haul mass and buffer power. The result is 24/7 motion with a calmer microgrid, less peak hardware, and a pit that sounds like a library with a gym.
- Onboard storage turns every stop into a chance to level the grid.
- Flywheels soak spikes (launches, dump lifts), protecting batteries and chargers.
- Regen downhill pays back the climb — electrons ride the elevator down.
Platform specs (mass‑produced, custom where it counts)
Mega Van — baseline
- Payload: 200 t
- Empty mass: ~190 t (includes pack)
- Top speed (site): 36 km/h (10 m/s)
- Climb: 5–10% grades at 10 m/s (assist lanes optional)
- Drive: 4‑in‑wheel motors, vector control
Energy modules
- Main pack: 3–5 MWh (LFP‑class); pack mass ~21–36 t
- Peak power (battery): 2–4 MW (C‑rate managed)
- Flywheel pod: 30–50 kWh, 2–5 MW burst, ~1–2 t
- Regen: ~70% of downhill potential captured
What the flywheel really does
It buffers power, not range. Think of it as a shock‑absorber for electrons. Launch off the bench? Flywheel gives 2–5 MW for seconds, batteries breathe easy at 0.5–1.0 C. Dump a 200‑ton load? Flywheel gulps the regen spike, then trickles it to the pack.
Energy flows & packs (numbers you can hold)
Per‑trip energy (net)
| Route | Energy / trip | Notes |
|---|---|---|
| Short & gentle • 1 km @ 3% grade | ~37 kWh | Regen pays most of descent |
| Base case • 2 km @ 5% grade | ~107 kWh | We’ll size pads by this |
| Longer haul • 3 km @ 5% grade | ~161 kWh | Bigger pads or trolley |
| Steeper • 2 km @ 8% grade | ~156 kWh | Flywheel shines here |
Assumes 200 t payload, 190 t empty, 10 m/s cruise, 90% drivetrain, 70% downhill regen.
Pack sizing by shift
3 trips/hour. Depth‑of‑discharge planned at 80% for long life.
| Route | 10‑h shift | 12‑h shift | Note |
|---|---|---|---|
| Short & gentle | ~1.4 MWh | ~1.7 MWh | 2 MWh pack comfy |
| Base case | ~4.0 MWh | ~4.8 MWh | 4–5 MWh pack |
| Long/steep | ~6.0–6.3 MWh | ~7.2–7.5 MWh | Use trolley or more charge time |
A 4 MWh pack at 0.32 MW average (base case) lasts ~12.5 h. Pads handle the rest; flywheels keep peaks polite.
Pre‑calculated routes
Per‑truck power & pad rating (base: 3 trips/h)
Charging only during stops ~15 min/h (25% duty). Charger+pack eff ~90%.
| Route | kWh/h | Pad power when docked | Recommend |
|---|---|---|---|
| Short & gentle | ~111 | ~0.5 MW | Single pad per bay |
| Base case | ~321 | ~1.5 MW | Dual pads at dump |
| 3 km @ 5% | ~483 | ~2.2 MW | Pads + trolley lane |
| 2 km @ 8% | ~468 | ~2.1 MW | Pads + flywheel focus |
Pad power ≈ (kWh/h) / (0.25 × 0.90). We schedule to avoid everyone docking at once.
Fleet energy (base)
20 trucks • 200 t • 3 trips/h • 2 km @ 5% grade.
| Metric | Value |
|---|---|
| Throughput | 288,000 t/day |
| Hauling energy | ~155 MWh/day |
| Avg fleet power | ~6.4 MW |
| Site envelope (with shovels/pumps) | ~12–18 MW |
Numbers match Part 1 so the story stays consistent.
What a trolley lane buys you (uphill assist)
Put a 2–3 MW overhead line on the uphill segment. It supplies the climb directly and tops packs at the same time.
| Case | Net kWh/trip | Pad power needed | Note |
|---|---|---|---|
| Base (no trolley) | ~107 | ~1.5 MW | As above |
| Uphill trolley 2 MW | ~20–40 | ~0.3–0.6 MW | Regen covers most of downhill |
Because uphill potential energy is ≈106 kWh/trip at 2 km/5%, powering that segment erases most net draw.
Charging & trolley options (pick the Lego you like)
Dump‑pad chargers
- 1.5–2.5 MW DC pantograph per bay
- Dock while dumping; 3–6 min bursts
- Heavy AC bus + site battery smooths upstream
Uphill trolley lane
- 2–3 MW overhead on the climb
- Supplies climb + trickle charges
- Slashes pack size or pad rating
Hot‑swap packs (optional)
- 5–8 min swap at the dump station
- Good for remote sites without trolley
- Requires spare pack pool (~10–20%)
Why not “just bigger batteries”?
Past ~5 MWh per truck the pack weight/space starts stealing payload and capex. It’s cleaner to keep packs reasonable and add in‑motion energy (trolley) or high‑power pads. Batteries do energy; flywheels do power.
Fleet orchestration (how the ballet stays smooth)
Relay brain
- Schedules dock windows so pad concurrency stays low.
- Staggers climbs to flatten power draw.
- Predicts tire and brake wear from telemetry; no surprises.
Microgrid rules of thumb
- Pads: 1 per 6–8 trucks (base case), 2 per 10 for headroom.
- Site battery: size to 1–2 hours of average fleet load.
- PV oversize: 1.5–2.0× average to charge trucks in daylight.
Safety & neighbors (boring by design)
Electrical safety
- Interlocked pads; no live contacts until fully docked.
- Pack fire cells are ceramic‑isolated; vent outside, not into cabins.
- Flywheel in armored drum; fail‑safe bearings; vacuum sensors.
People & peace
- Acoustic panels on chargers; fleet <75 dBA at fence.
- No diesel fumes, no NOx. Dust kept down with misters and paved lanes.
- Lighting is downward‑only; hawks still visit the future lake (Part 1).
Tap‑to‑open Q&A
“Can one truck power another?”
Yes, slowly. V2V through the DC link at safe rates for balancing. We mostly let trucks power the site — pad to battery — and the site powers the rest. Fewer cables on the road, more smiles.
“What breaks first?”
Tires, always tires. But regen + vector control reduce brake wear to comedy levels, and autonomy prevents pothole heroics. Packs cycle gently thanks to flywheels; lifetime looks like a long, quiet book.
“Is trolley worth the hassle?”
If your uphill segment is long or steep, absolutely. It erases ~100 kWh/trip at 2 km/5% and shrinks pad power by ~2–5×. Otherwise, pads alone are great for compact pits.
“Could we run 24/7 without stopping?”
Practically yes: dock‑while‑dumping + occasional micro‑stops. With trolley, packs arrive at dumps more charged than they left. The ballet doesn’t break stride.
Up next: Transport & Flows — Local vs Global (Part 8). Do we ship atoms or ship finished shapes? We’ll map the world’s arteries.