Energy storage
Battery chemistries, capacitors, supercaps — PCS and grid applications.
Lessons
Battery energy storage — chemistries, PCS, applications
Key parameters (V_oc, R_int, SoC, C-rate, cycle life). LFP dominates grid stationary, NMC for EVs. Bidirectional IGBT PCS. Value stacking: arbitrage + freq reg + peaker replacement. Hornsdale to 1 TWh by 2030.
Capacitor energy storage — PFC, harmonic filters, DC-link, supercaps
W = ½·C·V². Power-factor correction (kVAR = P·(tan θ_old - tan θ_new)), tuned LC harmonic filters, DC-link capacitors in inverters, supercapacitors (5-10 Wh/kg, 5-10 kW/kg, >1M cycles).
Long-duration energy storage — pumped hydro, CAES, flow, iron-air, thermal
LDES = >10 hr. Pumped hydro 95% of global (180 GW, RT 70-85%, 50-100 yr, geography-limited). Flywheel sub-sec to 30 min (E=½·J·ω², niche). CAES (Huntorf 1978, McIntosh 1991; adiabatic emerging). Flow batteries decouple P and E (VRFB, all-iron ESS). Iron-air Form Energy 100 hr at $20/kWh target. Thermal molten salt at CSP. DOE LDES Storage Shot: 90% cost cut by 2030. WoodMac: 1500 GW LDES by 2050.
Hydrogen production & fuel cells — electrolysis, PEM/SOFC, decarbonization
H2 value chain: production (electrolysis green / SMR grey/blue) → storage (compressed / liquid / NH3 / caverns) → use (industry, transport, grid). Electrolyzers: alkaline / PEM / AEM / SOEC. Fuel cells: PEM (vehicles) / SOFC (stationary CHP Bloom, 90%) / AFC / MCFC / PAFC. Round-trip 30-45%. IRA 45V PTC up to $3/kg; DOE $7B Hydrogen Hubs; EU 40 GW. Target $1/kg by 2030.