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.

rocks 10 to 700 degrees
http://helioscsp.com/novel-concentrated-solar-power-design-combines-the-solar-receiver-with-thermal-energy-storage/ Due to the novel design of directly radiative heat transfer as well as circulation flow, their design facilitates a higher temperature process, with a good solar to exergy conversion ratio (how much thermal energy can be converted to power) of 52% and charging and discharging efficiencies well beyond 99% and 92% at 770°C.

The rocks/heated air combination allows for a much wider working temperature range than current CSP. Molten salt storage, the state of the art commercially, is good at transferring heat, but it has a working temperature range between from 290°C – 560°C from its coldest to hottest (it mustn’t get hotter or it becomes unstable about around 600°C).

Because the rocks are solar heated from outdoor air temperature (so from say 10°C to around 700°C) the result is a much greater working range, resulting in a much higher efficiency, making for lower cost electricity production.

https://www.solarpaces.org/australian-researchers-assess-the-commercial-viability-of-solar-alumina-calcining/

firebrick storage
https://progrss.com/sustainability/20170924/firebrick-footprint-century-later/ Developed as early as 1600 BC in what is modern-day Turkey, firebricks – which are essentially bricks made of clay capable of withstanding high temperatures – are being eyed by scientists for thermal heat storage.

http://large.stanford.edu/courses/2017/ph240/hallock1/

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/