Timber energy structure structures.
Electrical power from the grid is stored as elastic potential energy in large laminated timber beams. The energy thus stored is converted back to electricity at times of high electricity demand. The linear spring action of the timber beam is converted to rotary motion at the electrical motor/generator by means of a rack and pinion, ball screw or similar high efficiency device.
Although the volumetric energy density is low in comparison to a chemical storage, the energy storage medium (timber) literally grows on trees. Power output is chiefly limited by the size of the connected electrical motor/generator. The timber is composed of carbon, derived from atmospheric CO2 during the life of the tree, at which time the tree also provides a home for birds.