In Factorio’s energy system, the Gravity Energy Storage Device is a key mid-to-late-game energy storage unit, inspired by real-world gravitational storage tech. It converts electricity to gravitational potential energy (and vice versa) via mechanics, acting as a stable "energy buffer"—a major upgrade from early accumulators (small capacity, high wear). Unlocked through specific research, it marks players’ transition to efficient energy management.
I. Core Functions
Its core role is balancing volatile renewable energy output with steady power demand, fitting four key scenarios:
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Surplus Recycling: Absorbs peak power from solar/wind (e.g., noon sunlight, strong winds), using electric engines to lift weights and store energy as potential energy, avoiding waste.
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Peak Demand Supply: Releases energy (10,000 kW charge/discharge power) via falling weights driving generators during production peaks or low renewable output, preventing downtime.
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Peak Shaving & Backup: Acts as tertiary storage (35 GJ capacity ≈ 9.73 MWh) for peak shaving and emergency power for core facilities (dozens of minutes).
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Uninterrupted Support: Works with grid dispatching to form a "generate-store-supply" loop (e.g., store daytime solar surplus, power night operations), ideal for remote mining.
II. Unlocking & Manufacturing
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Research: Unlock via "gravity_energy_storage" tech, requiring prior mastery of "Advanced Material Processing," "Chemical Science Pack," and "Electric Engine." R&D costs 100 tech points (1 Automation + 1 Logistic + 1 Chemical Science Pack) and takes 60 seconds.
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Manufacturing: Produced in Assembling Machine 3 with 300 steel plates, 2000 concrete, and 10 electric engines; takes 120 seconds.
III. Practical Performance
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Key Specs: 35 GJ capacity (nearly 1 hour of discharge at 10,000 kW), 70-80% efficiency (no chemical wear), and stable peak-shaving capability (slower response than lithium batteries but symmetrical power output).
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Scenario Value: Boosts renewable energy utilization by 30%+; serves as a transitional energy hub for high-power facilities (refineries, chip factories) pre-nuclear. No maintenance needs, making it more cost-effective than accumulators long-term.