Thermal storage

Popular mechanics
Letter by a person describing how he takes a galvanised tank and raps it in fiber glass. Finally sheets of polystyrene is rapped around the fiber glass enabling a storage tank that keeps hot water at the same temperature for two weeks.

sand
https://www.researchgate.net/publication/264935189_Sand_as_a_Heat_Storage_Media_for_a_Solar_Application_Simulation_Results

Amadeus
Starting in January 2017, AMADEUS (www.amadeus-project.eu) is the first project funded by the European Commission to research on a new generation of materials and solid state devices for ultra-high temperature energy storage and conversion. By exploring storage temperatures well beyond 1000 ºC the project aims at breaking the mark of ~ 600ºC rarely exceeded by current state of the art TES (thermal energy storage) systems. AMADEUS Project, through a collaborative research between seven European partners, aims to create new PCMs (phase change materials) based on silicon and boron alloys with latent heats in the range of 1000-2000 kWh/m3, an order of magnitude greater than that of conventional molten salts used in CSP (concentrated solar power). Also, a new kind of solid-state device, the hybrid thermionic-photovoltaic converter, will be developed for heat to power conversion at very high temperatures in the range of 1000-2000 ºC. The final objective of the project is to develop a new kind of extremely compact energy storage device that will eventually lead to a new generation of modular CSP systems, new electricity storage devices for the housing and district sectors, or new systems for grid-scale storage applications. https://zenodo.org/communities/amadeus-737054/?page=1&size=20

http://www.amadeus-project.eu/publications.html

https://zenodo.org/record/1289792#.W5J74xi6LM0

Underwater energy bags
https://www.youtube.com/watch?v=ktup6CAvfGo

cryogenic storage
https://www.youtube.com/watch?v=kDvlh_aG7iA

Hydrolic storage
https://www.youtube.com/watch?v=m3p_daUDvI8 Cut a huge cylindrical rock and lift it out of the ground with water. As it sags back under gravity it converts potential into kinetic energy.

Kinetic storage
https://stornetic.com/

greenhouse
http://solarenergyengineering.asmedigitalcollection.asme.org/article.aspx?articleid=2695484 pipe under ground for slow thermal release.

links
Air Engine

http://www.solardishsystem.com/