Supercapacitor Banks
Supercapacitor Transient Buffer System (STBS)
The Supercapacitor Transient Buffer System comprises hermetically sealed electric double-layer capacitor banks that provide millisecond-scale load buffering and bus voltage stabilization for lunar settlement power grids. By supplying up to 50 kW of peak power for sub-ten-second durations at greater than 95 percent round-trip efficiency, the unit absorbs high-rate transients from motor starts and communication bursts, protecting primary batteries across more than 500,000 cycles. Operating in the lunar environment necessitates hermetic cell packaging to prevent volatile organic electrolytes from outgassing in hard vacuum, thermal management to hold modules within their -40 °C to +65 °C operational envelope, and mitigation of long-term radiation-induced electrolyte decomposition across multi-decade service life.
High-power supercapacitor banks providing ultra-fast transient load buffering, power quality smoothing, and peak shaving for the Ark power bus
Purpose
Absorb and deliver high-power transients (motor starts, actuator pulses, communication bursts) within milliseconds, protecting the main battery banks and fuel cells from high-rate stress while maintaining power bus voltage stability
Context
L2-ESS-SCAP fills the power density gap that batteries and fuel cells cannot efficiently serve. While Li-ion banks handle energy-dense loads (minutes to hours) and fuel cells handle long-duration reserves, supercapacitors handle sub-second to minute-scale transients at very high power density. This extends battery cycle life by absorbing pulsed loads, smooths bus voltage during load switching, and provides ride-through power during source transfer events. Supercapacitors offer >500,000 cycle life and near-zero degradation per cycle, making them ideal for the 100-year mission with minimal replacement.
Principles
- ▸Electric double-layer capacitance stores energy electrostatically with no chemical reaction (no degradation per cycle)
- ▸Power density is 10-100x higher than batteries; energy density is 10-100x lower
- ▸Charge/discharge in milliseconds to seconds with >95% round-trip efficiency
- ▸Cycle life exceeds 500,000-1,000,000 cycles with minimal capacity fade
- ▸Voltage varies linearly with state-of-charge; DC-DC converter needed for constant output voltage
- ▸Self-discharge is higher than batteries (~5-10% per day) making them unsuitable for long-term storage
Typical implementations
- ▸Maxwell/Tesla 3000F cells (2.7V per cell, EDLC technology)
- ▸Skeleton Technologies SkelCap series (graphene-enhanced, higher energy density)
- ▸Hybrid supercapacitors (lithium-ion capacitors) for improved energy density
- ▸Spacecraft bus stabilization capacitor banks on GEO communication satellites
- ▸ISS power system bus regulation capacitor arrays
Lunar considerations
- ▸Vacuum environment: organic electrolyte in sealed cells is acceptable; no outgassing concern if hermetically sealed
- ▸Wide temperature operating range (-40C to +65C) reduces thermal management burden vs. batteries
- ▸Radiation effects on organic electrolyte decomposition over decades need characterization
- ▸Low mass per unit power makes supercapacitors mass-efficient for transient buffering role
- ▸Self-discharge means supercapacitors must be continuously trickle-charged; parasitic load on system
- ▸Lunar dust: sealed modules with no external exposure
Specifications
Functional
| primary function | Buffer high-power transient loads and maintain power bus voltage stability |
| inputs | DC bus power from L1-PDM for trickle charging and recharge after transient discharge, Load demand signals from L2-ESS-MGMT and L2-PDM-LOAD, Bus voltage reference from L1-PDM |
| outputs | High-power DC pulses to L1-PDM bus during transient demand events, Bus voltage stabilization (smoothing ripple and sag), Module health telemetry (ESR, capacitance, temperature) to L2-ESS-MGMT |
| peak power kw | 50 kW peak for <10 seconds |
| continuous power kw | 5 kW for up to 60 seconds |
| total energy kwh | 1-5 kWh (small energy, high power) |
| response time ms | <1 ms (near instantaneous) |
| round trip efficiency percent | >95 |
| cycle life | >500,000 full cycles |
| operating temperature c | -40 to +65 |
| self discharge percent day | 5-10 (requires continuous trickle charge) |
| esr mohm | <5 per module string |
Physical
| materials | Activated carbon or graphene electrodes, Organic electrolyte (acetonitrile or propylene carbonate based), Aluminum current collectors and cell cans, Aluminum or composite module housings, Busbar interconnects (copper or aluminum) |
| temperature range c | -40 to +65 (wide native operating range) |
| radiation | Moderate sensitivity; organic electrolyte may degrade; shielding recommended |
| dust | Sealed modules; no direct exposure |
| vacuum | Hermetically sealed cells compatible with vacuum environment |
Operational
| power consumption w | 25 |
| thermal range c | -40, 65 |
| lifetime years | 100 |
| mtbf hours | 1000000 |
Interfaces
Provides
- High-power transient pulses up to 50 kW peak and continuous bus voltage stabilization
- Module ESR, capacitance, voltage, temperature, and cycle count telemetry
Requires
- DC bus power for continuous trickle charging and post-transient recharge
- Charge management commands and coordination with battery/fuel cell dispatch
- Mounting racks and enclosures for supercapacitor module banks
- Robotic module replacement if capacitance degradation exceeds threshold (rare, ~30-50 year intervals)
Decomposes into
Cite this entry
Lunar Ark Codex. "Supercapacitor Banks" (L2-ESS-SCAP). Retrieved 10 September 2026, from https://lunarark.com/entry/L2-ESS-SCAP
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.