followed by a full-scale 30-m test at full pressure and maximum piston speed. The seal development is a solvable problem; it may even involve using an off-the-shelf product.
The piston seal is the last preliminary design milestone for the GPM. The next step is to build the proposed demonstration plant. It is for these tests that the Series B round financing is being sought.
Gravity Power holds the promise of reasonably priced, easily sited, and insignificant-environmental-impact bulk energy storage. I predict that the GPM will soon be a critical part of grid of the future, both in the U.S. and other countries.