News Release

Scientists use seaweed to create new material that can store heat for reuse

Peer-Reviewed Publication

Swansea University

Alginate beads - derived from heat - that can store heat

image: Beads which can store heat, which would otherwise be wasted, from various sources, including industrial operations and the summer sun. The new material has been made using alginate, an inexpensive, abundant and non-toxic seaweed derivative. view more 

Credit: SPECIFIC, Swansea University

Researchers from the SPECIFIC Innovation and Knowledge Centre and COATED M2A programme at Swansea University have collaborated with the University of Bath to make a groundbreaking advancement in thermal storage research, developing a new efficient material that is easily scalable and can be sized and shaped to fit multiple applications.                                                                    

Published in the Journal of Materials Science, the material has been made using alginate, an inexpensive, abundant, and non-toxic seaweed derivative.

The process starts with the dissolving of sodium alginate in water. Following this, expanded graphite is added, and a method of gelation is chosen:

The first method is achieved by transferring the solution into a mould for freezing. After being kept at - 20°C for over two hours, beads are formed and transferred to a saturated calcium chloride solution.

The second uses a drop-cast technique, with the mixture being dropped into thermochemical calcium salt, causing gelation on contact.

Once sufficient salt diffusion has occurred, the synthesised beads are filtered and dried at 120°C.

Compared to SPECIFIC's previous carrier material, vermiculite, the alginate-based beads from both methods offer a remarkable improvement in heat storage capacity.

The new spherical beads boast increased salt capacity, achieving up to four times greater energy density than the vermiculite carrier. This is facilitated by their efficient packing in a fixed bed that maintains good airflow. As a result, the new material can achieve the same heat energy storage capacity in just a quarter of the volume.

Jack Reynolds, who led the research as part of his doctorate at Swansea University, explains: 

"The ability to recover and store otherwise-wasted heat from various sources, including industrial operations and the summer sun, presents an exciting opportunity in the quest for sustainable and affordable energy resources. Our new heat storage material marks a significant step forward in realising this potential."

Dr Jonathon Elvins, Senior Technology Transfer Fellow and co-author, added: 

"SPECIFIC remains committed to driving innovation in thermal storage technology and actively collaborating with industry partners and researchers worldwide to accelerate the transition towards a greener and more sustainable future.”

"To explore new applications for this latest technology, we are preparing for a trial at Tata Steel UK’s Trostre steelworks to investigate ways of capturing waste heat from industrial processes for use elsewhere."

The research at SPECIFIC Innovation and Knowledge Centre and COATED M2A was funded by the European Regional Development Fund through the Welsh Government, the European Social Fund via the Welsh Government, the Engineering and Physical Sciences Research Council (EPSRC), and Tata Steel UK. It was also supported by the Industrial Decarbonisation Research and Innovation Centre.



  • Researcher Jack Reynolds putting the seaweed-based alginate solution into moulds for freezing into beads
  • Close-up of the newly formed alginate beads.
  • Jack Reynolds (left) with the alginate solution and Dr Jonathon Elvins (right) with the finished beads

Credit:  SPECIFIC, Swansea University


Notes to editors:

Read the paper in full: Development and characterisation of an alginate and expanded graphite based composite for thermochemical heat storage.


When reporting this story, please use Swansea University hyperlinks.

Founded in 1920, Swansea University is a research-led, dual campus university located along Swansea Bay in south Wales, UK. Its stunning beachfront campuses and friendly welcome make Swansea University a desirable destination for more than 22,000 students from across the globe. There are three academic faculties, delivering around 450 undergraduate and 350 postgraduate degree programmes.


Swansea is a UK top 30 institution, ranked 26th in the 2023 Guardian University Guide. In the 2021 Research Excellence Framework, 86% of Swansea University’s overall research and 91% of its research environment were classed as world-leading and internationally excellent, with 86% of its research impact rated outstanding and very considerable.


Swansea University is a registered charity. No. 1138342.  


For more information:

Kevin Sullivan, senior press officer, Swansea University;

01792 295050


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