Academic Foundation

Planetary Prototyping's energy storage system is not just a battery; it is a Closed-Loop Thermodynamic Machine. We integrate a solar thermal steam plant directly with a pseudo-hydro compressed air system, using a shared water buffer to bridge the two.

• The Thermal Heart: A closed-loop water reservoir circulates between the steam condenser and the air system. It captures waste heat, elevating water from 27°C (cooling the air compressor) to 90°C (heating the air expander).
• Pseudo-Hydro Staged Tiers: Instead of fragile mechanical pistons, we use Digital Hydraulics. Water is pumped into vertical pressure vessels, compressing the air 'spring' above it. By using Staged Pressure Tiers—shuffling air between low-cost low-pressure tanks and high-grade high-pressure tanks—we significantly reduce CapEx while maintaining precise pressure control.
• The "No-Release" Cycle: In this closed cycle, the air never leaves the system. It acts as a permanent pneumatic spring, compressing and expanding without venting. This eliminates emissions, ensures silent operation, and maintains maximum system pressure for instant reactivity.

A robust microgrid requires two contradictory traits: the massive inertia of a thermal plant and the split-second reflexes of a battery. Our hybrid design delivers both, allowing them to cover each other's weaknesses.

• Doubling Max Power: By running the steam turbine and the air expander simultaneously during peak demand, the system can output double the baseload capacity.
• Bidirectional Balancing: Steam turbines are slow to ramp up. The compressed air system acts as a fast-response regulator. It can instantly switch from "Generating" (adding power) to "Load" (absorbing excess power) in milliseconds, smoothing out grid frequency while the steam turbine adjusts at its own pace.
• Deep Storage: While batteries fade after hours, our thermal-backed storage can maintain output for days, ensuring resilience even during extended solar downtime.

Our design leverages the "Cheat Code" of thermodynamics: using waste heat to offset compression losses. By recycling the steam turbine's exhaust heat into the expansion cycle, we achieve efficiencies that defy standard mechanical storage limits.

• Thermal Uplift: Standard adiabatic compression loses energy to heat. Our near-isothermal design captures that heat in the water buffer. When combined with the thermal input from the steam cycle, the simulation demonstrates a Round-Trip Efficiency of ~101.5% (Electrical Output vs. Electrical Input + Thermal Reheat).
• Proven Simulation: As detailed in our 2022 thesis, the system was modeled against 4 years of real-world German grid data. The LSTM neural network accurately predicted price spikes, allowing the system to arbitrage volatility and maximize revenue.
• Island Mode Reliability: In disconnected "Island Mode" simulations, a system successfully balanced load and generation, prioritizing reliability over revenue to prevent blackouts.

The principles of thermodynamic efficiency and robotic control validated in the ST-CAES thesis were not limited to the power grid. The initial goal was to find a pilot site for the energy storage system, with municipal water treatment plants being a prime candidate due to their high, consistent energy needs.

However, during this feasibility analysis, a more immediate and impactful opportunity was discovered. The energy-intensive oxidation ditches themselves presented a critical optimization challenge. Instead of just powering the existing machinery more efficiently, the core logic of decoupled control and process automation from the ST-CAES research was applied directly to the wastewater process. This pivot led to the development of a novel retrofit design that solves the inherent inefficiencies of the oxidation ditch, creating a new solution entirely.