Energy Grid Storage with pumped thermal heat exchange

SB-100 California's renewable energy mandate

California ISO ( The California Independent System Operator ) has stated that up to 30% of solar power electric energy generated is wasted because cannot be used when is produced.

Technical Card:
  • The California Independent System Operator is a non-profit Independent System Operator serving California.
  • CAISO oversees the operation of California's bulk electric power system, transmission lines, and electricity market generated and transmitted by its member (

Having a system capable to store the energy generated in huge quantities at pick hours, and being relatively inexpensive, will solve Utility Companies dependency of "Peaker Plants" being fired (at pick hours) to cover the demand. Peaker plants are fossil-based power plants and are intense polluters.

Because Solar and Wind energy represents an intermittent source of power generation, the main goal is to have a huge reservoir of energy capable to add new energy in an incremental model at all time. It is widely understood that facilities for storing very large amounts of electric energy are key to any long-term plan to supplant fossil fuel with renewable energy and help reach California's main goal: all its electricity to come from carbon-free sources by 2045, joining Hawaii in going carbon-free by 2045.

In 2017, about 29 percent of California's electricity came from renewable energy.

In order to comply with SB-100 goals, specific storage technologies are called to provide fundamental support, and the most efficient and the most cost-sensitive it will be adopted. One of them has started to make forays in the industry: pumped thermal grid storage with heat exchange using solar salt.

SB-100 California Renewables Portfolio Standard Program: emissions of greenhouse gases.

Pumped thermal grid storage working principles:

The principles have been founded and described by Robert B. Laughlin, Nobel Price researcher at Department of Physics, Stanford University, Stanford, California as "Pumped thermal grid storage with heat exchange" and have been published in "Journal of Renewable And Sustainable Energy 9,044103(2017)".

Thermal Pump Electric Power Gene - Working Principles

Considering his study the energy storage is based on a thermal heat-pump grid storage technology described as a closed-cycle Brayton engine transfers of heat from a cryogenic storage fluid to molten solar salt. a pumped hydroelectric storage solution.

The excess of electrical power generated by renewables is stored as hot and cold in huge energy reservoirs following a differential temperature constrained condition. Released when they are requested in a reversing the process, they build the steam energy necessary to generate power using a heat pump with turbine - generator system. In this process, we have four distinct components: high temp storage, low temp storage, working fluid, heat exchange pump with turbine gene system.

High-temperature storage

As a material used for the high-temperature storage medium is solar salt. Solar salt has a well-known list of advantages such as low vapor pressure, high compatibility with steels, and environmental friendliness. It does not disintegrate in response to thermal cycling stresses the way a solid would. It creates no explosion hazard. The solar salt will be kept in steel containers.

Working fluid

The working fluid in this application is limited to gases that are extremely stable at high temperatures and far from liquefaction or solidification and they will travel from heat containers and respective chilled reservoirs towards the heat pump and turbine-generator system.

Solar salt can accommodate a higher energy density compared to the conventional type of deep cycle batteries and is not affected by deep cycle battery physical structure, constituting a constrained solution considering the possibility of electrical short and explosion.

The salt tanks can also be re-charged many thousands of times, for possibly up to 40 years.

Alphabet Inc.’ X-Malta Inc. building next-generation "Pumped Thermal Grid Storage System"

Alphabet Inc.’s secretive X moonshot lab is spinning off an energy-storage project with backing from billionaires including Jeff Bezos and Bill Gates under X-Malta Inc, name, a start-up looking to make a name using this type of technology.

Pumped thermal grid storage with heat exchange

X-Malta Inc. is building a grid-scale energy storage technology that stores electricity from renewable energy sources as heat inside large tanks of high-temperature molten salt and as cold in large tanks of chilled liquid. The system can discharge electricity back to the grid when energy demand is high - effectively “time to shift” energy from when it’s produced to when it’s most needed.

It plans to build and sell industrial-grade, grid-scale energy storage solutions that can be located anywhere in the world. These storage solutions will collect and store large quantities of energy to dispatch quickly as electricity on demand.

X-Malta Inc., the newly independent company, raised $26 million led by Breakthrough Energy Ventures LLC, a fund that counts Bezos, Masayoshi Son and Ray Dalio among its investors. Gates is chairman.

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The information posted herein has been compiled by Clean Energy Brands from OEM product data and reputable publications. All rights reserved!


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