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The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the weekly PCM newsletter. Or join the discussion on LinkedIn.




Research roundup: Spherical encapsulation; thermal therapy respirator; nanoporous composite; PCM effect on cement; more

Ben Welter - Friday, May 03, 2019

From Journal of Energy Storage:

Performance comparison of four spherically encapsulated phase change materials for medium temperature domestic applications

From International Journal of Thermal Sciences:

Exploration of a thermal therapy respirator by introducing a composite phase change block into a commercial mask

From Renewable and Sustainable Energy Reviews:

Review on nanoporous composite phase change materials: Fabrication, characterization, enhancement and molecular simulation

From Sci:

The Effect of Phase Change Materials on the Physical, Thermal and Mechanical Properties of Cement 

From Applied Energy:

High energy-density and power-density thermal storage prototype with hydrated salt for hot water and space heating

From Journal of Thermal Science and Engineering Applications:

Thermal Cycling of Calcium Chloride Hexahydrate With Strontium Chloride as a Phase Change Material for Latent Heat Thermal Energy Storage Applications in a Nondifferential Scanning Calorimeter Set-Up
Numerical Investigation of Scheffler Concentrator Receiver for Steam Generation Using Phase Change Material

From IntechOpen:

Solar Thermal Energy Storage Using Paraffins as Phase Change Materials for Air Conditioning in the Built Environment

From Reactive and Functional Polymers:

Design and fabrication of pH-responsive microencapsulated phase change materials for multipurpose applications

From Advances in Fluid and Thermal Engineering:

Experimental Investigation on a Solar Thermal Energy Packed Bed Sensible Heat Storage Combined with Latent Heat Storage

From Bulletin of Materials Science:

Development of an acetanilide/benzoic acid eutectic phase change material based thermal energy storage unit for a passive water heating system

From International Journal of Heat and Mass Transfer:

Solidification performance of a latent heat storage unit with innovative longitudinal triangular fins

PCM briefing: Ice Energy signs distribution deal with Fuji Bridex; Pluss food bag now available in 13 states across India

Ben Welter - Friday, May 03, 2019

Ice Energy of Santa Barbara, Calif., has signed a distribution agreement with Fuji Bridex Pte Ltd. Under the agreement, Fuji Bridex will market, install and service Ice Energy’s commercial and residential ice-based thermal energy systems across Singapore, Japan, Australia and Southeast Asia. 

PronGO food bagPluss Advanced Technologies of Gurgaon, India, announced on LinkedIn this week that its PronGO insulated food bag is now available in 13 states across India and has "moved over 150 metric tons of #frozen and #chilled foods safely every month." The bag, right, uses PCM cooling pouches to keep perishable foods cool for up to eight hours and frozen foods frozen for up to five hours. 

1414 Degrees of Australia fired up the burners for the first time at its gas thermal energy storage system at the Glenelg Wastewater Treatment Plant in Adelaide this week. The system will enable South Australia Water to time-shift the use of its biogas to produce electricity and heat on demand, rather than use the biogas as it is generated. 

• Registration is open for the 5th International Conference on Industrial Waste Heat Valorisation May 21-22 in Kortrijk, Belgium. Among the topics: "Thermal storage technologies for medium and high temperatures," "Thermal (heat and cold) storage in industrial processes," "Thermal storage in P2H2P (Power to Heat to Power)" and "Increase flexibility of your energy system by adding thermal storage."

Alexium International Group Ltd. this week announced that it has entered into a supply agreement with an unnamed "multi-billion dollar North American manufacturer of mattresses." Alexium says the agreement makes it "the preferred supplier of phase change material (PCM) products for textile applications to its bedding products with the intent to form a strategic partnership." 

Brooklyn Bedding's new Aurora hybrid mattress features PCM "gel beads" that melt and solidify as needed to maintain a comfortable temperature. A reviewer for the Stamford Advocate gives the mattress high marks: "While I admittedly didn't take a thermometer to bed with me, I can say that this technology isn't marketing fluff — it actually worked for me. I never overheated, and neither did my partner who tends to sleep much hotter than I do."

MIT researchers have developed thin polymer films that conduct heat better than ceramics and many metals, including steel. “We think this result is a step to stimulate the field,” says Gang Chen, the Carl Richard Soderberg Professor of Power Engineering at MIT, and a senior co-author on the paper. “Our bigger vision is, these properties of polymers can create new applications and perhaps new industries, and may replace metals as heat exchangers.” 

Matthias WuttigMatthias Wuttig, a professor at RWTH Aachen University, was honored by the Materials Research Society as a 2019 Fellow for making "path-breaking contributions to the advancement of phase-change materials, including unraveling their unique bonding mechanism, unconventional transport properties and unusual kinetics." The society, founded in 1973, has more 14,500 members who are material experts from industry, academia and national labs. 

• Posted by Warmilu founder Grace Hsia on LinkedIn this week: "So honored Doctors Without Borders is piloting the Warmilu infant warming incubator blankets in Bangladesh. Thank you again to the whole Doctors Without Borders team and the Warmilu team stepping up to support infant healthcare initiatives. It was a great honor to be an abstract presenter at Doctors Without Borders MSF 2019 International Paediatric Days! We just saw the abstract published in ResearchGate and two of my personal + career dreams have finally come true: working with Doctors Without Borders and being published! Huge thank you to the whole MSF Scientific Committee and to Dr. Nadia Lafferty for your words of wisdom and amazing insights." Warmilu's IncuBlanket uses packs filled with sodium acetate trihydrate to keep infants warm for up to five hours.

Research roundup: Surface functionalization of composite PCM; EnergyPlus optimization; direct expansion solar heat pump; more

Ben Welter - Friday, April 26, 2019

From Applied Surface Science:

Effects of surface functionalization on thermal and mechanical properties of graphene/polyethylene glycol composite phase change materials

From Applied Energy:

Facile flexible reversible thermochromic membranes based on micro/nanoencapsulated phase change materials for wearable temperature sensor
Shape-remodeled macrocapsule of phase change materials for thermal energy storage and thermal management
Investigation on the thermal performance of a high temperature packed bed thermal energy storage system containing carbonate salt based composite phase change materials
Toward a new method for the design of combined sensible/latent thermal-energy storage using non-dimensional analysis
Strategic control and cost optimization of thermal energy storage in buildings using EnergyPlus
Adaptive measures for mitigating urban heat islands: The potential of thermochromic materials to control roofing energy balance

From Solar Energy Materials and Solar Cells:

Poly(styrene-co-divinylbenzene-co-acrylamide)/n-octadecane microencapsulated phase change materials for thermal energy storage

From Renewable and Sustainable Energy Reviews:

Recent advances in direct expansion solar assisted heat pump systems: A review
Review on nanoporous composite phase change materials: Fabrication, characterization, enhancement and molecular simulation

From Energy and Buildings:

Experimental Testing of Phase Change Materials in a Warm-Summer Humid Continental Climate

From International Journal of Energy Research:

Development of pentadecane/diatomite and pentadecane/sepiolite nanocomposites fabricated by different compounding methods for thermal energy storage

From Applied Thermal Engineering:

Heat transfer performance of graphene nano-platelets laden micro-encapsulated PCM with polymer shell for thermal energy storage based heat sink

From Journal of Applied Polymer Science:

Investigations on thermal properties of microencapsulated phase‐change materials with different acrylate‐based copolymer shells as thermal insulation materials

From Solar Energy:

Experimental investigation on the impact of thermal energy storage on the solar still performance coupled with PV module via new integration

From Thermochimica Acta:

Nanoencapsulated phase change material with polydopamine-SiO2 hybrid shell for tough thermo-regulating rigid polyurethane foam

From International Journal of Heat and Mass Transfer:

Optimization of the detailed factors in a phase-change-material module for battery thermal management

From Journal of Traffic and Transportation Engineering :

A review on the best practices in concrete pavement design and materials in wet-freeze climates similar to Michigan

From Case Studies in Thermal Engineering:

Study of a passive solar air heater using palm oil and paraffin as storage media

From Acta Microscopica:

Preparation of Graphene Hybrid Material and Thermal Properties of Polymer Composites

Research roundup: PCM use in mortars; compatibility with selected plastics; myo-inositol sugar alcohol; more

Ben Welter - Tuesday, April 23, 2019

From Materials:

Phase Change Materials for Energy Efficiency in Buildings and Their Use in Mortars

From Polymer Testing:
From Renewable Energy:

From Molecules:

From Applied Energy:

Natural convection during melting in vertical finned tube latent thermal energy storage systems
Year-round performance analysis of a photovoltaic panel coupled with phase change material

From Energy Procedia:

A Review of the Performance of Buildings Integrated with Phase Change Material: Opportunities for Application in Cold Climate

From Journal of Applied Polymer Science:

Encapsulation of polar phase change materials via multiemulsification and crosslinking method and its application in building

From Journal of Energy Storage:

Thermal performance of shell and tube latent heat storage unit: Comparative assessment of horizontal and vertical orientation
Experimental investigation of phase change in a multitube heat exchanger

From Chemistry Select:

Preparation and Thermal Properties of Stearic Acid/n‐Octadecane Binary Eutectic Mixture as Phase Change Materials for Energy Storage

From Journal of Materials Research:

Synthesis of novel shape-stabilized phase change materials with high latent heat and low supercooling degree for thermal energy storage

From Science of Advanced Materials:

Fabrication and Performance of Polyurethane/Polyurea Microencapsulated Phase Change Materials with Isophorone Diisocyanate via Interfacial Polymerization
Design and Analysis of Battery Box Based on Graphite-Phase Change Material and Air Cooling

From Experimental Techniques:

Design, Build, and Test a Hybrid Cooling System for Crash Helmet

From Journal of Thermal Analysis and Calorimetry:

Capric acid/intercalated diatomite as form-stable composite phase change material for thermal energy storage
Preparation and thermal performances of microencapsulated phase change materials with a nano-Al2O3-doped shell

PCM briefing: Ice Energy signs distribution deal; Bloom joins Sunamp as board chairman

Ben Welter - Monday, April 22, 2019

Ice Energy of Santa Barbara, Calif., has reached distribution agreements with four California companies to sell, install and maintain its ice-based thermal storage system, the Ice Bear 20. The companies are Correy Baker Heating and Air of Murrieta; Emery Mechanical Engineering of San Diego; H3 of Santa Barbara; and SunRize Mechanical of Temecula. “This distribution network will enable us to further expand our footprint in the residential market in Southern California,” said Marcel Christians, co-COO of Ice Energy.

Sonoco ThermoSafe and AirBridgeCargo Airlines have announced a global partnership agreement for the leasing of the PharmaPort 360 temperature-controlled shipping container. The agreement will enable pharmaceutical shippers to lease PharmaPort 360 containers directly from AirBridgeCargo.

Martin Bloom• Thermal battery maker Sunamp Ltd. of Scotland has appointed Martin Bloom as chairman of the board. Bloom, right, has extensive experience in high-growth technology and renewable energy companies, including Chinese solar company Renesola and Loughborough-based fuel cell specialist Intelligent Energy. Bloom succeeds Sunamp’s founding chairman, Bob Pettigrew, who oversaw its early growth.

Nominations are being accepted for the 2019 Poncelet Prize for Innovation in Microencapsulation, co-sponsored by Procter & Gamble and the Bioencapsulation Research Group. The award recognizes innovation in process design and modernization; development of new core and shell materials; innovation in characterization methods; or innovation in emerging fields of applications. The deadline for submitting nominations is May 31, 2019.

Peli BioThermal is rebranding its Chronos temperature-controlled shippers. CoolGuard PCM will replace Chronos Express, and CoolGuard Advance will replace Chronos Advance. The CoolGuard shippers will offer configurations with fewer components and additional temperature set points, such as 16º C.

• Registration is open for "Phase Change Material & Passive Cooling in Large Venues," a lunch-hour presentation by Henderson Engineers. The free event, sponsored by AIA Kansas City, will be held June 12 at the Center for Architecture & Design in Kansas City, Mo.

Axiotherm GmbH's kraftBoxx thermal energy storage system is a finalist for a Smarter E Award in the renewable energy category. KraftBoxx is a joint development with Klara Energy and Tuxhorn within the scope of the PCM-based HeatSel product line marketed by Axiotherm. Winners will be announced May 15 in Munich.

• PCM expert Harald Mehling's new book is available on Amazon: "Understanding the Basics of Energy: An Introduction from Simple to Complex Situations."

Tempur-Pedic of Lexington, Ky., says its new TEMPUR-breeze mattress will help sleepers "stay up to 8 degrees F cooler through the night." According to Tempur-Pedic: "At about 80°F, the molecules within TEMPUR-breeze’s most efficient Phase Change Material (PCM) to-date, PURECOOL+, activate, shifting from a solid to a liquid to absorb massive amounts of heat. For the first time, Tempur-Pedic’s scientists successfully altered these proprietary molecules to deliver more phase change material, increasing its capacity to absorb heat by 2x compared to other PCM."

• Two new ASHRAE publications will be available in June: "Owner’s Guide for Buildings Served by District Cooling" and an updated edition of the "District Cooling Guide" for designers and building owners around the world.

• Researchers at Sweden's KTH Royal Institute of Technology have developed a polyethylene glycol-infused wood material that could be used to make windows that absorb heat during the day and release it into the home at night. The researchers are working to increase the heat storage capacity of the transparent wood, reports.

Patent application: Thermal energy storage systems utilizing phase change material

Ben Welter - Friday, April 19, 2019

U.S. patent application 20190101337 (applicant SABIC Global Technologies B.V., Bergen op Zoom, Netherlands):

"A thermal energy storage system utilizes a phase change material with an encapsulating material surrounding the phase change material. The encapsulating material fully contains the phase change material to prevent passage of the phase change material out of the encapsulating material and/or prevent direct contact of the phase change material with external objects. The encapsulating material is a high density polyethylene (HDPE), which may be a non-crosslinked or crosslinked HDPE. In a method of forming a thermal energy storage system a phase change material is surrounded with the encapsulating material."

PCM briefing: $33M in funding for CSP thermal storage research; Walero undergarment put to the test in race simulator

Ben Welter - Friday, March 29, 2019

• The U.S. Department of Energy has announced $33 million in research funding to advance technologies that work toward achieving the department's 2030 cost target of 5 cents per kilowatt-hour for CSP-generated electricity with at least 12 hours of thermal energy storage. "This research," DOE writes, "includes new materials and technologies that significantly reduce the cost of manufacturing, enable new energy storage technologies, and develop solutions that enable a solar field to operate autonomously without any human input."

Jack MitchellWalero racewear, which uses Outlast phase change technology to regulate temperature in race and rally drivers, has been put to the test on reigning British GT4 champion Jack Mitchell in a temperature-controlled race simulator. The tests were directed by racing performance coach Dean Fouache. On the first day, Mitchell, right, wore standard Nomex underwear; on the second day, he wore Walero underwear. Three measurements were recorded every five minutes during the hourlong tests: body temperature, heart rate and weight loss. In all three areas, Walero showed measurable advantages over the Nomex. "Jack sweated around 40 percent less in the Walero underwear and his average heart rate was eight beats less over the course of the hour," Fouache told Autosport magazine. "So, all in all, relatively conclusive results - even though it is a small comparison test."

• New this month from Central West Publishing in Australia: "Phase Change Materials," edited by Vikas Mittal, an associate professor of chemical engineering at the Petroleum Institute in Abu Dhabi.

• The International Conference on Innovative Applied Energy in the United Kingdom earlier this month featured a number of experiments with phase change materials, including Auburn University's development of micro-encapsulated phase change materials that can be combined with many different media. Other PCM research included a bio-composite made with hemp lime concrete and a novel utilization of fly ash to encapsulate phase change materials.

James Joule• The 200th anniversary of the birth of physicist James Prescott Joule will be commemorated with the unveiling of a plaque in Sale, United Kingdom, in April. The English physicist and mathematician, who gave his name to the unit of energy, was born on Dec. 24, 1818, in Salford. He died in Sale in 1889.

• The deadline for submitting manuscripts for "Phase Change Materials of Buildings," a special issue of the journal Buildings, is Sunday, March 31. Dr. Morshed Alam of Australia's Swinburne University of Technology is the guest editor.

Research roundup: Hollow aluminum bricks; animal-fat-based PCM for building applications; floor heating system design; more

Ben Welter - Wednesday, March 27, 2019

From Applied Thermal Engineering:

Thermal characteristics of aluminium hollowed bricks filled with phase change materials: Experimental and numerical analyses

From Energies:

Assessing the Potentiality of Animal Fat Based-Bio Phase Change Materials (PCM) for Building Applications: An Innovative Multipurpose Thermal Investigation

From Sustainable Energy and Fuels:

Innovative design of microencapsulated phase change materials for thermal energy storage and versatile applications: A review

From Environmental Research:

Design and analysis of phase change material based floor heating system for thermal energy storage

From Solar Energy Materials and Solar Cells:

Direct impregnation and characterization of Colemanite/Ulexite-Mg (OH) 2 paraffin based form-stable phase change composites
Experimental analysis of solar air collector with PCM-honeycomb combination under the natural convection

From Journal of Molecular Liquids:

Fabrication and characterization of phase change nanofluid with high thermophysical properties for thermal energy storage

From Renewable Energy:

Investigation of thermal properties and enhanced energy storage/release performance of silica fume/myristic acid composite doped with carbon nanotubes

From International Journal of Thermal Physics:

Thermal Property Characterization of a Low Supercooling Degree Binary Mixed Molten Salt for Thermal Energy Storage System

From Journal of Energy Storage:

From Energy Procedia:

Development of Corn-Oil Ester and Water Mixture Phase Change Materials for Food Refrigeration Applications
Experimental study on the performance of a new encapsulation panel for PCM's to be used in the PCM-Air heat exchanger

From Case Studies in Thermal Engineering:

Thermal characteristics on melting/solidification of low temperature PCM balls packed bed with air charging/discharging

PCM system inefficiencies blamed on design flaws, operator errors

Ben Welter - Monday, March 25, 2019

A PCM-based thermal energy storage system installed in an 11-story building at an Australian university used just 15 percent of its heat storage capacity to shift peak cooling load, according to researchers who monitored system performance for 25 months.

Morshed AlamA team led by Morshed Alam of Swinburne University of Technology in Hawthorn found that the PCM reduced chiller cooling load by 12 to 37 percent in winter but remained inactive in summer, partly because the ambient temperature was not cold enough to charge the PCM tank. The tank was designed to reduce the daytime cooling load on the chiller by 33 percent.

The results of the study are reported in "Energy saving performance assessment and lessons learned from the operation of an active phase change materials system in a multi-storey building in Melbourne," published in Applied Energy earlier this year.

"The factors that contributed to the underperformance of active PCM system," the researchers concluded, "include mismatch between designed and actual operation of the PCM system, inefficient operation logic of the system, poor material quality, and limited knowledge of maintenance staffs during the operation stage."

FlatICE PCM panels in TES tankThe TES system, installed in the 11th floor of Swinburne's Advanced Manufacturing and Design Centre, completed in 2015, was designed to minimize the daytime cooling load on the chiller and increase the building energy efficiency. The system includes a 5x4x2-meter tank filled with 5,120 FlatIce PCM panels made by PCM Products Ltd. Each HDPE panel is 500x250x45 mm and is filled with a salt hydrate PCM with the melting temperature of 13–15 °C. Water is used as the heat transfer fluid.

The researchers reported two problems with the PCM: a "very high degree of supercooling" that slowed the solidification process and a measured latent heat capacity (53 joules per gram) that was much lower than the manufacturer's specification (160 J/g).

Alam, a senior research fellow at Swinburne's Centre for Sustainable Infrastructure, Department of Civil and Construction, answered a few questions about the research in an email interview.

Q: This the first comprehensive report I've seen that analyzes the actual performance of a PCM/TES system in a commercial building. Do you know of others? For example, has the TES system at Melbourne CH2 undergone this kind of analysis?

A: "I am aware of the PCM system installed in CH2 building in Melbourne. But no such study was carried out to understand the performance of the system. The system went out of order within 5-6 years."

Q: Any theory on why the PCM's thermal storage capacity of 53 J/g, as measured using differential scanning calorimetry, did not match the manufacturer's specified capacity of 160 J/g?

A: "The DSC test is widely used by the researchers around the world to test PCM capacity. But it may not be an appropriate approach to test PCM thermal energy storage capacity. That is why we are now in the process of conducting an experimental study where 6 degree Celsius chilled water will be supplied in a small PCM tank. We will measure the flow rate, melting and solidification temperature and time required to completely solidify and melt the PCM. Based on the result we will optimize the system."

Q: Have the researchers' recommendations been put into practice?

A: "We are now working with our facilities department to put the recommendations in practice. We need to finish the optimization and cost-benefit analysis study. Then we can define the ideal operating condition of PCM in this building. We will be able integrate those maybe before next summer in Australia."

I shared results of the paper with Zafer Ure of PCM Products Ltd. and asked him to comment on the authors' observations on supercooling and specified-vs-measured latent heat capacity.

Zafer Ure"We have been supplying the same PCM for the last 20 years and many of the installations are 10~15 MWh levels," Ure wrote. "You cannot use the DSC machine to work out the latent heat for sulphate-based hydrated salts, it only picks up one of the chemicals in the mixture and gives you the data for that chemical. This is a well-known handicap for the DSC application for sulphate-based PCM testing. Moreover, DSC sample is less than gram quantities and this is a mixture of multiple salts, nucleating agent, stabilizers and thickening agent so if you do not pick up the correct mixture, which is very difficult unless you pick it up from the reactor vessel while you are making the PCM (i.e. while the agitators and mixers working at the correct temperature (some salts crystallize at room temperatures), you may not be able to pick up true sample.

"They took the sample out of one of the containers and no idea where and how they took the sample. If you do not have the true sample, especially lack of nucleating agent in the very small gram quantity sample, you can get it very wrong data as this is the case for their DSC. We would not ship any PCM unless QA release the goods and our records show the product supplied was within the standard capacity level. The actual latent heat can only be established using air test and actual freeze and melt profiles.

"If they managed to charge and discharge the tank fully they would have measured the tank performance which would have shown the true TES capacity. Sounds like their chilled water design and control did not allow that and therefore there is no way of evaluating the TES tank performance."

PCM briefing: Sonoco ThermoSafe partners with Cargolux; Axiom Exergy partners with Leap

Ben Welter - Friday, March 22, 2019

Amrit RobbinsAxiom Exergy has announced a partnership with Leap, a technology company that serves as an aggregator of flexible power loads in California. Axiom says the arrangement will unlock grid services revenue for its customers, including three Whole Foods Market facilities in Northern California.

Axiom's "Refrigeration Battery" system is designed to reduce a supermarket's peak power use by up to 40 percent and provide backup cooling during power outages. It uses the excess capacity of existing refrigeration systems to "store cooling" at night by freezing tanks of salt water.  

"Axiom Exergy is excited to announce that Whole Foods has connected three of their buildings to our platform, which will serve as our first Virtual Power Plant," Axiom CEO Amrit Robbins wrote in a LinkedIn post Friday. "Axiom’s platform will intelligently manage 340 kW of dispatchable load across these facilities in order to generate more value for Whole Foods and to help stabilize California’s electricity grid."

Sonoco ThermoSafe has announced a global partnership agreement with Cargolux for the leasing of the PharmaPort 360 temperature-controlled bulk shipping container. The agreement enables pharmaceutical shippers to lease PharmaPort 360 containers directly from the all-cargo airline based in Luxembourg.

• On LinkedIn this week, Ice Energy posted an update on its 5 MW contract with Riverside Public Utilities in California: "We are working to install 9 Ice Bear thermal #energystorage batteries and 13 rooftop units with Inland Mechanical Services Inc. at a car dealership in Riverside."

• A high-temperature thermal energy storage system inaugurated in Denmark this week stores heat in stones. The test system uses surplus wind power to generate hot air, which heats up small stones in an insulated container to 600 degrees. The stored heat is used to generate electricity when the wind doesn't blow. The system was developed by the energy company Seas-NVE, in collaboration with DTU Energy, Aarhus University Geoscience, Danish Energy, and Rockwool.

Alexium International CEO Bob Brookins was among the presenters at the International Conference on Textile Coating and Laminating in Berlin earlier this month. His topic: "Advanced applications of phase change materials."

• The German Aerospace Center (DLR) is investigating whether Germany’s coal plants can be refitted to serve as thermal energy storage sites. "The research body, which has a track record in concentrated solar power (CSP) development, is planning a pilot that will involve ripping out the boiler from an old coal plant and replacing it with a molten salt thermal storage tank that will be heated using excess renewable energy," Greentech Media reports. "If the concept works, then advocates say it could help safeguard coal generation jobs while giving Germany tens of gigawatts of storage capacity for renewable energy load-shifting on the German grid." DLR says it is preparing a commercial-scale pilot in association with an unnamed German utility.