| system | initial cost ($ + hrs) / unit | annualized cost ($ + hrs) / unit | sqft building | sqft land | other resources | revenue | market cost | benefits | | -------------------- | ----------------------------- | -------------------------------- | ------------- | --------- | ----------------------------- | ------- | ----------- | -------------------------------------------------------------------------- | | pumped hydro storage | $4.2M + 25,000 hrs | $378k + 3,650 hrs | 2,000 | 18 acres | Water supply, Grid connection | 0 | $912k | Energy independence, Load shifting, Emergency backup, Multi-use reservoirs | #### Assumptions - 1000-person micro society with 10 MWh daily usage - 48-hour storage capacity (20MWh) for resilience - 300ft elevation difference available - Round trip efficiency of 75% (90% pump × 85% turbine × 98% transmission) - Michigan climate (cold weather considerations) - Multi-use reservoirs (recreation, fish habitat, irrigation) - Community provides labor and operates owned equipment - Internal resource unit costs: - Electricity: $0.15/kWh - Water: $0.01/gallon - Land: Community owned - Equipment operation: $4-6/cubic yard ##### System Sizing - 300 ft head + 25,000 GPM (36" pipe at ~8ft/s) -> 1.18 MW peak power output - 5 acres at 40 ft depth (60M gallons, 300k cubic yards) -> 46.10 MWh electricity storage #### Market Solutions $912k / year Based on equivalent battery storage: - Battery system: $400/kWh × 20,000 kWh = $8M - Inverters/BOS: $2M - Replacement every 10 years - O&M: $100k/year Total annualized: $912k/year #### Labor 2,400 Hours / year | task | hours/year | notes | | --------------------------- | ---------- | ---------------------------------------- | | Daily system monitoring | 730 | 2 hours/day checks and logging | | Routine maintenance | 520 | Weekly inspections and servicing | | Reservoir maintenance | 480 | Cleaning, fish management, vegetation | | Equipment servicing | 400 | Pump/turbine maintenance | | Water quality management | 180 | Testing and treatment | | Emergency response/training | 90 | Safety drills and procedures | | total labor (hours) | 2,400 | | #### Operating Costs $168k / year | component | external cost ($) | internal cost ($) | notes | | ----------------------- | ----------------- | ----------------- | ------------------------------- | | Equipment maintenance | 40,000 | 0 | Parts for pump/turbine/controls | | Water treatment | 15,000 | 0 | Chemicals and filters | | Environmental testing | 8,000 | 0 | Required monitoring | | Reservoir maintenance | 5,000 | 0 | Materials and supplies | | total annual cost | 68,000 | 0 | | #### Initial Costs $4.2M + 25,000 hrs -> $210k + 1,250 hrs / year | Component | Initial Cost ($ + hrs) | Lifespan (Years) | Amortized Cost/Year ($ + hrs) | Justification | | --------------------- | --------------------- | ---------------- | ---------------------------- | ------------------------------------------- | | Upper Reservoir | $600k + 6,000 hrs | 50 | $12k + 120 hrs | 3 acres × 30ft deep, HDPE liner | | Lower Reservoir | $800k + 8,000 hrs | 50 | $16k + 160 hrs | 15 acres × 20ft deep, fish habitat | | Piping System | $1.2M + 4,000 hrs | 40 | $30k + 100 hrs | 36-inch steel pipe, valves, supports | | Pump/Turbine Unit | $1M + 3,000 hrs | 25 | $40k + 120 hrs | 2.2MW reversible Francis unit | | Control Systems | $400k + 2,000 hrs | 15 | $27k + 133 hrs | SCADA, sensors, automation | | Equipment Purchase | $200k + 2,000 hrs | 20 | $10k + 100 hrs | Excavator, trucks, screening equipment | | total initial cost | $4.2M + 25,000 hrs | - | $210k + 1,250 hrs | | #### System Outputs | Output Type | Daily Units | Annual Units | Internal Cost ($/unit) | Internal Cost (hrs/unit) | Notes | | -------------- | ----------- | ------------ | ---------------------- | ------------------------ | ------------------------------ | | Energy Storage | 30 MWh | 7,300 MWh | $0.023/kWh | 0.33 hrs/MWh | Based on round trip efficiency | | Peak Shaving | 1.5 MW | 547.5 MW | $0.020/kW | 0.25 hrs/MW | Demand charge reduction | | Backup Power | 2.2 MW | 803 MW | $0.018/kW | 0.20 hrs/MW | Emergency capacity |