Sunamp Heat Batteries

Andrew Bissell, Sunamp


Whilst two and a half times more heat is consumed than electricity globally, new developments in heat have not been the focus on considerable innovation in recent years.

Sunamp Ltd, which is based in East Lothian, was founded in 2005 by successful technology entrepreneur, Andrew Bissell, who wanted to produce an innovative solution to develop heat batteries that store energy as heat, which can be released on-demand to provide heat and hot water.  



As over half the world’s population live in densely populated cities and countries there is a clear need for heat energy stores in homes to move beyond gas and for homeowners to adopt solar and heat pumps without compromising on space requirements. Therefore Andrew set out to develop a truly practical heat energy store that was much more efficient and compact than hot water tanks and physically small enough for people to easily store in their homes.

Sunamp’s innovative idea was to create heat storage systems, using Phase Change Materials (PCMs) that are capable of storing and releasing heat as they change phase. In this way excess energy, which would normally be wasted, can be stored as heat for later use. The patented, non-toxic Sunamp Heat Battery stores and provides heat to warm a building or deliver hot water. The energy is released in much the same way as a hand warmer works. 

The issue that Sunamp faced with PCMs is incongruent melting, which affects the PCMs ability to store and release heat over a long lifetime. As a consequence, this was hampering the performance in Sunamp’s heat batteries.


Through Interface, Sunamp was successfully matched with Colin Pulham, Professor of High-Pressure Chemistry and Head of the School of Chemistry at the University of Edinburgh, to analyse the PCMs to develop systems that store renewable energy as heat. They did this by developing additives, which would reduce the effects of any incongruent melting and, therefore, significantly improve the PCM’s heat storage properties. This initial project was funded through a Scottish Funding Council Innovation Voucher and although provided some early results, it was only in the close out meeting that the discussions led to further areas to be investigated. The resulting project proposal was successfully awarded an Engineering and Physical Sciences Research Council (EPSRC) Case studentship which subsequently resulted in the PhD student upon graduation joining the Sunamp team as their Materials Scientist.


Since the initial partnership that Interface brokered with the University of Edinburgh in 2008, Sunamp has continued to develop their relationship with Professor Pulham and commenced a new relationship through Interface with Dr Tadhg O’Donovan, School of Engineering and Physical Sciences; Mechanical, Process and Energy Engineering at Heriot-Watt University. The value of the relationship between University of Edinburgh and Sunamp has supported career development and employment for post graduate and undergraduate students, a new area of research into phase change materials, leveraged several £100k of funding and facilitated access to facilities such as the Diamond Light Source UK facility. The collaborative partnership will be submitted as an Impact case study to the Research Excellence Framework (REF) 2021 highlighting the significant benefits that have been realised.

Professor Colin Pulham stated:

“This is the most rewarding and enriching academic/industrial collaboration that I have been involved in.  It is particularly gratifying to see the impact of fundamental research being applied in real world applications in such a short time.”

Andrew Bissell said:

“Professor Colin Pulham is extremely good at understanding a problem from the perspective of the company and then applying his own intellect, that of his students, the wider resources of the university and its’ academic networks to solving the problem. Colin and his ERI colleagues have been pragmatic and creative in developing the commercial relationship in such a way that it optimises the benefits for all parties.”

“Meeting Professor Colin Pulham at University of Edinburgh School of Chemistry in 2010 has led to the most amazing academic-industry partnership and development of what we think is the world’s best, most stable, heat energy storage material.”

Follow on Projects

Under an Energy Technology Partnership ​(ETP) student agreement two significant discoveries in relation to Sunamp have been published. Professor Pulham now has a Sunamp focussed team working within the university and some of the collaborative projects have secured EPSRC Impact accelerator and Innovate UK funding. 

In 2014 Sunamp also secured a Knowledge Transfer Partnership with Heriot- Watt University which aimed to integrate and optimise Heat Batteries with Solar Thermal and Solar Hybrid PV-T (Photvoltaic-Thermal) Panels to develop a competitive, on-demand heat supply solution for domestic households.

In April, 2016, Sunamp raised £3.2m for its sales and manufacturing function in its latest funding round led by an international private investor in the energy market.

“The global thermal energy storage market is expected to reach $1.8 billion by 2020 and we are excited about the potential of our product to solve a worldwide problem,” said Chief Executive, Andrew Bissell.

In August 2017 a consortia, which includes Professor Colin Pulham ​with Sunamp and Vantage Power, has been awarded £250k from Innovate UK for a project that will look to develop a novel vehicle thermal management solution that addresses hybrid electric bus cabin warm up and thermal loads in stop/start and all electric modes.

In 2017 Sunamp and the University of Glasgow's School of Engineering have partnered on a £2 million project linked to clean power and heat generation from the China-UK Research and Innovation Bridges programme, a joint UK China initiative under the Newton Fund developing solutions for agri-food, energy, healthcare, and urbanisation.

Watch the interview with Professor Pulham and Andrew Bissell here: 

Please note that Interface administers the Innovation Voucher Scheme on behalf of the Scottish Funding Council. All funding applications are reviewed on a case by case basis by the Scottish Funding Council, guidelines can be found here.