
Credit: Fraunhofer FEP
Heat exchanger with metallized zeolite.
In Germany, 55 percent of final energy consumption goes towards heating and cooling. However, a lot of heat dissipates unused because it is not generated as and when required. Thermal storage using zeolite material allows heat to be stored for long periods of time without losing any. Fraunhofer researchers are now working on significantly improving the thermal conductivity of zeolites.
Many roofs nowadays host solar collectors that provide homes with warm water. This works quite well in the summer; however, heating demand peaks in the winter when homes need heating. Thermal storage therefore needs to be able to store a portion of the excess heat for use at a later date. Traditionally, large water tanks have been used for this purpose; water is heated in these tanks and the heat is then directly stored as heat. The problem with this method is that large volumes are required, and in spite of good insulation, heat is also lost. In contrast, thermochemical storage enables thermal energy produced in the summer to be preserved for use in the cold winter. Zeolites are one such storage solution. Unlike water, zeolites do not store the heat directly – instead, the heat removes the water that is stored within the material. In the energetic state, zeolites are therefore completely dry; conversely, when water vapor is passed through the pellets, heat is released. The advantage of this is that the energy is not stored in the form of increased heat but in the form of a chemical state. This means that heat is not lost during long-term storage. There is one drawback: Zeolites have poor thermal conductivity, which makes transferring the heat from the heat exchanger to the material and back difficult.
Coating with aluminum
A team of researchers at the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP have now solved this problem through their work on the ZeoMet project. “We coated the zeolite pellets with aluminum – this doubled thermal conductivity after just the first attempt without negatively impacting water adsorption and desorption. We are currently aiming to increase this by five to ten times through adjusting the coatings,” says Dr. Heidrun Klostermann, Project Manager at Fraunhofer FEP. While this sounds relatively simple, it actually poses considerable challenges. This means that for a liter of granules with a five millimeter-diameter grain size, around ten thousand of these tiny pellets must be evenly coated with aluminum. For a grain size of one millimeter, this amounts to one million pellets with an overall surface area of 3.6 m2. The smaller the grain, the more challenging the process. However, smaller grains also increase the specific power density of thermal storage systems. In order to achieve sufficient thermal conductivity, the coat must also be tens of micrometers thick – for vacuum coating processes, this is a lot thicker than the norm.
Nevertheless, the researchers conquered these challenges. To do so, they looked to thermal evaporation, whereby aluminum wire is continuously fed onto a heated ceramic plate in a vacuum, where the aluminum is evaporated and deposited onto the granules as a layer of aluminum. The pellets must be continually circulated in a barrel so that they are all covered evenly. “The main difficulty lay in coating the granules while they roll around as well as ensuring that the coating was applied evenly to a sufficient degree,” says Klostermann. “The excellent collaboration of our engineers, physicists and precision mechanics was the principal asset in helping us to achieve.
Also an option for cooling
Not only are zeolites a good method of thermal storage: They can also help provide cooling for domestic use alongside solar collectors as well as for mobile applications. For example, in commercial vehicles, heat lost from the power unit could be used for air conditioning as part of a thermochemical cycle. From the viewpoint of the Fraunhofer FEP researchers, the hybrid materials used for this present new challenges. As a result, the scientists are looking to strengthen their connections with materials developers and systems engineers from research and industry, in the hopes of advancing solutions for the flexible supply of heating and cooling.
Original Article: Thermal storage for the energy transition
More from: Fraunhofer Society
The Latest Updates from Bing News & Google News
Go deeper with Bing News on:
Thermal energy storage
- Ten energy storage technologies that want to change the worldon November 30, 2023 at 7:24 am
Another oil giant, Shell, is backing another thermal energy storage technology that can pack power into shoebox-sized blocks of metal alloy particles. Excess energy is used to heat the alloy particles ...
- IIT Roorkee Leads Comprehensive Study on Advanced Grid-Scale Energy Storage Technologies, Unveiled by Ministry of New and Renewable Energyon November 30, 2023 at 4:33 am
Shri BS Bhalla released a comprehensive study titled "Advanced Grid-Scale Energy Storage Technologies," conducted by IIT Roorkee under the leadership of Prof Arun ...
- New Google geothermal electricity project could be a milestone for clean energyon November 28, 2023 at 5:00 am
An advanced geothermal project has begun pumping carbon-free electricity onto the Nevada grid to power Google data centers there, Google announced Tuesday. Getting electrons onto the grid for the ...
- Australian startup begins work on agrivoltaic project with thermal storageon November 26, 2023 at 11:30 pm
Graphite Energy, a thermal storage company, is building a facility in Australia to demonstrate how renewable energy and agriculture can co-exist through agrivoltaic and greenhouse systems.
- Thermal storage company breaks ground on its renewable agriculture facility in NSWon November 26, 2023 at 8:50 pm
Australian thermal storage company, Graphite Energy, has broken ground on its Lake Cargelligo facility in New South Wales which aims to demonstrate how renewable energy and agriculture can coexist ...
Go deeper with Google Headlines on:
Thermal energy storage
[google_news title=”” keyword=”thermal energy storage” num_posts=”5″ blurb_length=”0″ show_thumb=”left”]
Go deeper with Bing News on:
Long-term energy storage
- Battery storage data platform Modo Energy raises $15 million to break into US, Europeon November 29, 2023 at 8:44 am
The funding is meant to help Modo expand beyond Great Britain, starting with entering the Texas and ERCOT market, then eventually expanding across Europe and USA.
- Pylontech and BloombergNEF Jointly Release Global Residential Energy Storage Market White Paperon November 27, 2023 at 11:09 pm
Pylontech and BloombergNEF (BNEF) achieved a significant milestone in advancing the energy storage industry through the joint release of an in-depth white paper titled "Scaling the Residential Energy ...
- How does energy storage impact grid reliability?on November 27, 2023 at 4:00 pm
Energy storage systems can be classified into two categories: short-term and long-term. Short-term energy storage can provide power for minutes to hours, and is mainly used for frequency ...
- Unlocking the benefits of carbon capture and storage for Ontario’s sustainable energy futureon November 26, 2023 at 4:01 pm
Mitigating emissions, powering progress: a closer look at carbon capture and its positive impact on the environment and economy. Ontario’s successful journey to a net-zero futur ...
- Future of long-term energy storage isn’t about lithium, it’s about battery supply chainson November 23, 2023 at 5:02 pm
Dr. Thomas Nann examines the benefits and limitations of lithium-ion batteries, imploring Australia to embrace disruptive innovation, not incrementalism.
Go deeper with Google Headlines on:
Long-term energy storage
[google_news title=”” keyword=”long-term energy storage” num_posts=”5″ blurb_length=”0″ show_thumb=”left”]