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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.




PCM briefing: Axiom lowers energy costs at Whole Foods store; EnergyNest has opening for senior engineer

Ben Welter - Monday, February 19, 2018

• Nearly a year ago, a Whole Foods in Los Altos, Calif., connected a thermal battery system made by Axiom Exergy to the store's refrigeration system. Whole Foods pays Axiom a monthly fee for the saltwater-based technology. Axiom says that payment, coupled with a lower monthly power bill, amounts to less than what the grocer was paying its utility before the batteries were installed. 

• Thermal battery maker EnergyNest AS of Norway is looking to hire a senior engineer to work in its main office outside Oslo.  

• The schedule has been posted for the 2018 GlobalChem Conference & Exhibition in Washington, D.C., Feb. 28-March 2. Most of the sessions focus on the Toxic Substances Control Act, the Global Harmonized System of Classification and other regulatory topics. 

Applications are being accepted for the Women and Minorities in Science, Technology, Engineering and Mathematics Fields Grant Program (WAMS). The program supports research and extension projects that will increase participation by rural women and underrepresented minorities from rural areas in science, technology, engineering and mathematics.

• CONTISOL, a solar reactor that can run day or night, is being tested by researchers in Germany. The reactor uses concentrated solar power and thermal energy storage.

Registration is still open for the second annual European Chemistry Partnering event, to be held Feb. 23 in Frankfurt, Germany. It's a chance to pitch innovations and connect with investors and decision-makers in the chemical industry.

• U.K.-based Sure Chill Co., whose water-based refrigeration technology is used to keep vaccines cool without the need for grid-based electricity, has been shortlisted for a 2018 St. David Award in Innovation, Science and Technology. 

• The U.S. Federal Energy Regulatory Commission has voted to clear a path for energy storage projects in the capacity, energy and ancillary services markets. Commissioner Cheryl LaFleur noted that newer technologies “like some of the batteries, flywheels, compressed air, new forms of thermal storage, are rapidly gaining commercial viability and scale.”

Novel thermal resonator draws power from daily temperature swings

Ben Welter - Friday, February 16, 2018

MIT thermal resonator test device

Researchers at the Massachusetts Institute of Technology have developed a system that uses phase change material and graphene to convert daily fluctuations in ambient temperature into electrical power. 

The system, called a thermal resonator, is described in a paper published in the journal Nature Communications.

“We basically invented this concept out of whole cloth,” one of the authors, professor Michael Strano, told MIT News. “We’ve built the first thermal resonator. It’s something that can sit on a desk and generate energy out of what seems like nothing. We are surrounded by temperature fluctuations of all different frequencies all of the time. These are an untapped source of energy.”

MIT News writes:

"The researchers realized that to produce power from temperature cycles, they needed a material that is optimized for a little-recognized characteristic called thermal effusivity — a property that describes how readily the material can draw heat from its surroundings or release it. Thermal effusivity combines the properties of thermal conduction (how rapidly heat can propagate through a material) and thermal capacity (how much heat can be stored in a given volume of material). In most materials, if one of these properties is high, the other tends to be low. Ceramics, for example, have high thermal capacity but low conduction.

"To get around this, the team created a carefully tailored combination of materials. The basic structure is a metal foam, made of copper or nickel, which is then coated with a layer of graphene to provide even greater thermal conductivity. Then, the foam is infused with a kind of wax called octadecane, a phase-change material, which changes between solid and liquid within a particular range of temperatures chosen for a given application.

"A sample of the material made to test the concept showed that, simply in response to a 10-degree-Celsius temperature difference between night and day, the tiny sample of material produced 350 millivolts of potential and 1.3 milliwatts of power — enough to power simple, small environmental sensors or communications systems."

The researchers say the system could be used, for example, to continuously power remote sensing systems for years.

Ice Energy buys back program to distribute 1,800 commercial ice batteries

Ben Welter - Friday, February 16, 2018

Ice Energy, the California company that partnered with NRG Energy a year ago to install up to 1,800 behind-the-meter ice batteries in commercial buildings in Orange County, has bought back the program. Payment terms were not disclosed. In an e-mail interview, Ice Energy CEO Mike Hopkins explained the strategic shift.

Q: What spurred your decision to buy back the program?

A: NRG was the owner of the program but they decided to divest all their renewables including this project. We bought the project back from NRG last month and are financing it ourselves. We have almost 1800 Ice Bears available but are in discussions with several major property owners who will start taking down large chunks.

Q: The agreement with NRG called for the installation of up to 1,800 Ice Bear 30s, providing a total of up to 25.6 MW of peak storage capacity to Southern California Edison under 20-year power purchase agreements. How long was the NRG program active, and how many Ice Bears were installed?

A: During most of the time NRG owned the program, it was on hold due to regulatory delays. The delays were caused by requests for re-hearings and court appeals unrelated to our program, which was part of a much larger procurement by SCE that included a controversial gas peaker. The program got the regulatory green light last March, but that more or less coincided with NRG’s move out of renewables, which effectively kept the program on hold. As a result, only a few units for the City of Tustin were installed.

Ice Bear 30Q: Can you share performance data on the Ice Bears installed through the NRG agreement?

A: The Ice Bears installed for the City of Tustin have performed like the other 1200 or so units in operation – better than 98% availability which is better than any other storage technology, or grid asset for that matter.

Q: Can you name commercial property owners that participated in the Ice Bear program through NRG?

A: In addition to the City of Tustin who had their Ice Bears installed during NRG’s ownership of the program, the following commercial property owners signed up during NRG’s ownership and will now have their Ice Bears installed by us:

• A global bank
• John Wayne Airport
• Marconi Auto Museum
• Medical Eye Services
• 7 Diamonds

Q: Can you name any of the major property owners you're now in talks with?

A: We're in ongoing discussions and identifying initial target sites with the largest Orange County real estate developers and property management firms.

Q: Will the program change in any significant way under Ice Energy's direction?

A: Yes, under Ice Energy's direction we're able to respond more quickly and tailor our offering to meet individual customer needs. To accelerate adoption, for a limited period of time, Ice Energy is offering new participants free HVAC replacement in addition to free Ice Bears. We are also now able to work more efficiently with our utility partner on this program through our direct interaction. The end result of these changes is more units placed more quickly to more customers.

Q: When will the first units be installed?

A: The first installations under our ownership of the program will be next month which will be the beginning of almost three years of installing Ice Bears under our program. Once installed, the Ice Bears will then provide OC participants 20 years of utility bill savings and reduced greenhouse gas emissions.

Research roundup: Acrylic PCM microcapsules; paraffin-water nanoemulsion; two-tank molten salt TES; more

Ben Welter - Wednesday, February 14, 2018

Non-linear system identification of a latent heat thermal energy storage system [Applied Thermal Engineering]

Tailoring of bifunctional microencapsulated phase change materials with CdS/SiO2 double-layered shell for solar photocatalysis and solar thermal energy storage [Applied Thermal Engineering]

Preparation of acrylic PCM microcapsules with dual responsivity to temperature and magnetic field changes [European Polymer Journal]

Paraffin wax–water nanoemulsion: A superior thermal energy storage medium providing higher rate of thermal energy storage per unit heat exchanger volume than water and paraffin wax [Energy Conversion and Management]

Preparation and characterization of stearic acid/polyurethane composites as dual phase change material for thermal energy storage [Journal of Thermal Analysis and Calorimetry]

Efficiency analyses of high temperature thermal energy storage systems of rocks only and rock-PCM capsule combination [Solar Energy]

Thermal performance analysis of PCM wallboards for building application based on numerical simulation [Solar Energy]

Thermal energy storage in district heating: Centralised storage vs. storage in thermal inertia of buildings [Energy Conversion and Management]

Two-tank molten salts thermal energy storage system for solar power plants at pilot plant scale: lessons learnt and recommendations for its design, start-up and operation [Renewable Energy]

PCM briefing: Croda merger talks reported; RAL PCM members to meet March 1

Ben Welter - Monday, February 12, 2018

• British specialty chemicals maker Croda International Plc has held unsuccessful talks with Ashland Global Holdings Inc. about a possible merger, a source familiar with the matter told Reuters last week.

Croda recently redesigned the CrodaTherm website, The new site offers improved navigation and searchability, a wider range of potential PCM applications and profiles of the CrodaTherm technical team. Visitors can register to log in and download datasheets and order samples. "We are excited to launch this new website, making it even easier for our customers to find us and the products they need," said Graeme Tweddle, global managing director for energy technologies at Croda.

• Members of the RAL Quality Association PCM, a European-based organization established in 2004 to develop standards for the phase change material industry, will meet in Düsseldorf, Germany, on March 1. On the agenda: Quality and testing specifications; improvements to the association's website; member content on the BUILD UP Web portal; promotion of PCMs in the European Union, Germany, Netherlands and the United States; and registration of RAL quality marks.   

Sonoco ThermoSafe is accepting registrations for the company's first Leading Minds Seminar, to be held June 6-7 in Philadelphia. Co-hosted by ELPRO, the seminar is a chance for pharmaceutical manufacturers, supply chain partners and government representatives to discuss temperature-assurance packaging and data monitoring in a collaborative environment. Day two includes a visit to ThermoSafe's design and testing lab in Montgomeryville, Penn.

Sonoco is No. 90 on Barron's inaugural list of "The 100 Most Sustainable Companies." 

• A "measurement and verification study" of a Viking Cold Solutions TES system installed in a 320-square-foot walk-in freezer at a supermarket in Fremont, Calif., showed an 18 percent net reduction in energy consumption.   

• The deadline is Monday, Feb. 12, to submit a concept paper for ARPA-E's OPEN 2018 competition. Up to $100 million is available for new projects that "transform the way we generate, store and use energy."

DLR Group, which part of a public-private collaboration working to develop PCM-based cooling and heating methods for Agua Fria Canyon View High School, has been named one of Arizona's "40 Companies to Watch" in 2018 by AZRE magazine. 

• Entries are being accepted for Bio-Based World News' 2018 Innovation Awards. The four categories are product of the year, chemical innovation of the year, best use of alternative feedstocks and industry story of the year. The entry deadline is Feb. 23. Winners will be honored March 20 at the World Bio Markets conference in Amsterdam. 

• Nantucket, Mass., has approved the installation of an Ice Bear thermal storage and air-conditioning unit in a building owned by the town. Last summer, Genbright won a $1.5 million grant from the state to install the units in more than 200 Nantucket homes, with the goal of reducing peak energy demand and staving off the need for a third undersea power cable for the island. But some residents voiced skepticism about the technology, prompting the town board to approve the test installation.

• Shippers have found that cocoa butter can be hard to contain on long ocean voyages. There have been reports of the material leaking out of containers as it changes phase, clogging bilges and generally making a mess. The Cargo Incident Notification System, established in 2011 to share information on all cargo-related incidents, has issued guidelines that recommend the material be shipped in refrigerated containers, particularly when passing through hot climate zones. 

Research roundup: Heat transfer model based on energy asymmetry; smart concretes; traction transient cooling; more

Ben Welter - Wednesday, February 07, 2018

A new heat transfer model of phase change material based on energy asymmetry [Applied Energy]

Multifunctional smart concretes with novel phase change materials: Mechanical and thermo-energy investigation [Applied Energy]

The melting of salt hydrate phase change material in an irregular metal foam for the application of traction transient cooling [Thermal Science and Engineering Progress]

Solar Energy Latent Thermal Storage by Phase Change Materials (PCMs) in a Honeycomb System [Thermal Science and Engineering Progress]

Fabrication and characterization of diethylene glycol hexadecyl ether-grafted graphene oxide as a form-stable phase change material [Thermochimica Acta]

One-dimensional model of a stratified thermal storage tank with supercritical coiled heat exchanger [Applied Thermal Engineering]

Using silicagel industrial wastes to synthesize polyethylene glycol/silica-hydroxyl form-stable phase change materials for thermal energy storage applications [Solar Energy Materials and Solar Cells]

Steam-PCM heat exchanger design and materials optimization by using Cr-Mo alloys [Solar Energy Materials and Solar Cells]

Sodium acetate trihydrate-chitin nanowhisker nanocomposites with enhanced phase change performance for thermal energy storage [Solar Energy Materials and Solar Cells]

Preparation and thermal properties of fatty acid/diatomite form-stable composite phase change material for thermal energy storage [Solar Energy Materials and Solar Cells]

Patent application: Encapsulation of thermal storage medium

Ben Welter - Tuesday, February 06, 2018

U.S. patent application 20180016482 (assignee University of South Florida, Tampa, Fla.): 

"In one embodiment, a method for depositing metal on a polymer surface, the method includes coating the polymer surface with a binding metal to render the polymer surface solvophillic and/or hydrophilic and depositing a further metal on the binding metal-coated polymer surface."

Research roundup: Eutectic organic PCMs; diatomite/CNTs/PEG composites; cellulose insulation; more

Ben Welter - Tuesday, February 06, 2018

From Data in Brief:

Prediction of the Properties of Eutectic Organic Phase Change Materials

From Energy and Buildings:

Diatomite/CNTs/PEG composite PCMs with shape-stabilized and improved thermal conductivity: Preparation and thermal energy storage properties

From Solar Energy:

Thermal performance of phase change materials (PCM)-enhanced cellulose insulation in passive solar residential building walls

From Energy Procedia:

A Parametric Study about the Potential to Integrate Phase Change Material into Photovoltaic Panel
Investigations on thermal environment in residential buildings with PCM embedded in external wall
Passive Cooling Using Phase Change Material and Insulation for High-rise Office Building in Tropical Climate
A Study on Latent Heat Energy Storage Performance of Tetradecane
Erythritol-Vermiculite form-stable phase change materials for thermal energy storage

From Applied Thermal Engineering:

Modification of expanded graphite and its adsorption for hydrated salt to prepare composite PCMs

From Renewable Energy:

Experimental Investigation of Solar Chimney with Phase Change Material (PCM)
Effect of retrofitting a silver/water nanofluid-based photovoltaic/thermal (PV/T) system with a PCM-thermal battery for residential applications

From International Journal of Thermal Sciences:

Thermal charging performance of enhanced phase change material composites for thermal battery design

From Colloids and Surfaces A: Physicochemical and Engineering Aspects:

Preparation and characterization of high-temperature non-flowing SiO2/EG/paraffin composites by high-temperature refining

From Materials Today: Proceedings:

Experimental analysis of thermal energy storage by phase change material system for cooling and heating applications

From Materials & Design:

Thermal conductivity enhancement of phase change materials with form-stable carbon bonded carbon fiber network

From Sustainable Cities and Society:

Experimental study on thermal performance improvement of building envelopes by integrating with phase change material in an intermittently heated room

From International Journal of Refrigeration:

Phase-change thermal energy storage using spherical capsules: performance of a test plant

PCM briefing: va-Q-tec opens North American headquarters; Viking Cold Solutions begins Phoenix-area installation

Ben Welter - Friday, January 19, 2018

• PCM maker va-Q-tec AG officially opened its new North American headquarters in Langhorne, Penn., this week. Va-Q-tec will use the 20,000-square-foot facility to showcase new products and to manufacture its small temperature-control shipping containers. The location will also serve as a hub for the company's rental and repair operation. “The investment in this new facility is a testament to our commitment to grow the business and expand our footprint in North America," said CEO Dr. Joachim Kuhn.

Drones that deliver sterile mosquitoes in the fight against the Zika virus will be field tested in Latin America early this year. The system, developed by the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture's Insect Pest Control Laboratory, uses phase change material to keep the mosquitoes inactive during transportation. 

• New from Greentech Media: "The Next Five Years in Energy Storage According to 500 Energy Professionals"

• New from Global Info Research: "North America Advanced Phase Change Materials (PCM) Market by Manufacturers, Countries, Type and Application, Forecast to 2022"

• New from Technavio: "Global Advanced Phase Change Materials Market 2017-2021

Viking Cold Solutions has begun installing its PCM-based thermal energy storage system in a 10,000-square-foot freezer at the Bashas food distribution center in the Phoenix area. The system, which consists of salt-hydrate-filled panels suspended from warehouse ceilings, is designed to significantly reduce energy costs by shifting peak demand to nighttime hours.

• The cost of renewable energy is falling so fast that it should be a consistently cheaper source of electricity than fossil fuels by 2020, according to a new report from the International Renewable Energy Agency

Utility Dive takes a close look at Nantucket Island's "hybrid" plan to add energy storage, including thermal storage, to stave off expensive grid enhancements.

Patent application: Thermal energy storage apparatus with PCM

Ben Welter - Friday, January 19, 2018

Neothermal patent drawingU.S. patent application 20180017337 (applicant NeoThermal Energy Storage Inc., Timberlea, Canada):

"A thermal energy storage apparatus is disclosed. The apparatus includes a base and fluid flow plates which cooperate with the base to define a cavity; a phase change material contained within the cavity; an extendable extension spring [40] at least partially contained within the phase change material [14]; and end plates which cooperate with the fluid flow plates to define fluid flow channels. Inlet and outlet ports allow for the ingress and egress of a heat exchange fluid into the fluid flow channels. In operation, the extension of the extendable extension spring induces solidification of at least a portion of the phase change material from a supercooled liquid state to a solid state, releasing thermal energy, allowing for the transfer of thermal energy across the fluid flow plates from the phase change material to the heat exchange fluid."