SAGE Geosystems在德克萨斯州开创了一种独特的地下蓄能方式，其原型已经向德州电网展示了3兆瓦（MW）的储能和释放能力，并计划进一步扩展。与全球占主导地位的抽水蓄能不同，SAGE的系统通过垂直钻井至约3公里深、裂解岩石并储存高压水，将传统的“抽水蓄能”模式倒置，有效实现远高于常规水电储能几倍的能量密度。

该系统最大优势在于能以显著低于锂电池的单位成本储存能源，并支持更长时间储能。由于其主要硬件成本是一次性固定投入，而非按容量递增，这导致系统设计运行越久，单位储能成本越低。此外，它能通过灵活调配，将低谷时期生产的可再生能源（如太阳能）储存，并在高价时段出售，理论上可以使所储存电力价值翻倍。

目前，除SAGE外，其他EGS（增强地热系统）企业也在开展类似项目，例如欧洲的HYSTORE计划正探索地下含水层的大规模热能储存，而其他研究者则尝试利用钻孔技术。德州项目的成功表明，创新性颠覆传统技术有望在大规模能源存储领域带来重大突破。

SAGE Geosystems in Texas has pioneered a unique underground energy storage method, with its prototype already demonstrating the ability to store and release 3 megawatts (MW) of power to the Texas grid and plans for further expansion. Unlike conventional pumped hydropower which dominates the global grid-scale storage sector, SAGE’s system employs vertical drilling to around 3km deep and fractured rock to store high-pressure water, effectively inverting the traditional “pumped hydro” model and achieving several times greater energy density.

The key advantage of this system is its ability to store energy at a significantly lower unit cost than lithium batteries, while supporting much longer storage durations. Since its primary hardware costs are fixed and not cumulative per unit like batteries, the cost per unit of stored energy decreases the longer the system is designed to run. Additionally, it enables flexible generation, allowing renewable energy (such as solar power) produced in surplus periods to be stored and sold later at higher prices, potentially doubling the value of the stored electricity.

Currently, other Enhanced Geothermal System (EGS) firms are also pursuing similar approaches, such as Europe’s HYSTORE project exploring large-scale underground thermal energy storage in aquifers, and some researchers looking into borehole techniques. The Texas pioneers’ success demonstrates that turning conventional ideas upside down can lead to significant breakthroughs in large-scale energy storage technologies.