By Anthony Harrington
Really disruptive technologies tend to be fairly rare in the renewable energy market. However, the heat batteries developed by Sunamp, which specialises in this area, look to be capable of being more disruptive than most of the innovations one sees in this space.
Andrew Bissell, the CEO of Sunamp, claims that his products are highly likely to make conventional hot water cylinders obsolete in a relatively short space of time. The technology is now in its third iteration and is barely a third of the size of a typical hot water cylinder, such as households use for hot water.
However, the company is currently prototyping much larger versions capable of scaling up to provide the heating needs of commercial companies from palette-sized to container-scale. These would be ideal as a supplemental driver for large scale district heating networks.
“We started developing this technology around 2006, in terms of defining the concept. In 2009, with help from the University of Edinburgh, with whom we continue to have a very fruitful partnership, we started the practical development,” Bissell explains.
It has taken half a decade to refine the technology to the point where it has successfully gone through proof of concept trials in domestic housing. As Bissell explains, the basic technology is analogous to the little hand warmers that golfers and others will know well. In these devices a liquid turns to a solid and heat is released in the process.
Sunamp’s heat batteries use a proprietary solid/liquid material devised by Sunamp in partnership with Edinburgh University’s School of Chemistry. The system can capture heat in a variety of ways. In domestic heating contexts it can be run off photo voltaic solar panels on the house roof, off-peak or renewable grid electricity, heat pumps, biomass or conventional boilers. The commercial scale or district heating models can be configured to capture waste heat directly.
“In 2013, the Department of Energy and Climate Change, as it then was, gave us a contract to put our thermal storage system, alongside off-peak electricity and air-source heat pumps, into seven homes as a proof of concept trial. That was very successful – we were able to heat the homes at half the cost of natural gas. We had some retail sales on the back of that and in 2017 we won a fiercely contested competitive contract from Local Energy Scotland, on behalf of the Scottish Government, to put our heat batteries into 650 homes. These were in two housing associations, East Lothian Housing and Castle Rock Edinvar, which is part of the much larger Places for People Group,” he notes.
Bissell points out that being just a third of the size of a conventional hot water cylinder, the thermal storage battery has real benefits for both housing developers and the householder. For a start, in a large development it frees up very significant amounts of floor space, and householders get an airing cupboard that has a decent amount of storage space in it instead of being two thirds full with a cylinder.
The thermal battery is also more energy efficient than the vast majority of cylinders, being A or A+ rated across the full size range whereas only a few makes of hot water cylinder offer even one or two A rated models. The bulk are B and C rated in terms of energy efficiency. That creates around £50 to £150 savings a year.
If the battery is being run off PV panels, it is being heat charged through the day and will hold its heat for up to two weeks. This gives the householder a much better return on their investment in solar panels than simply putting excess electricity into the grid.
“Another strong point in favour of our thermal batteries is that they don’t need all the extras that go with a hot water cylinder,” Bissell explains. There is no need for safety valves, an expansion tank or a discharge pipe. The installation is much simpler, so although the thermal battery is probably some £100 to £150 more expensive than a hot water cylinder, the householder saves roughly the equivalent amount on the installation. Plus there is no need for the compulsory annual safety inspection that hot water cylinders require, saving up to £300 per year in maintenance fees.
The standard model is about the size of a combi boiler and delivers fast-flowing hot water on demand. It heats the water to a selectable temperature, between 40 and 55°C and provides over 180 litres of hot water. For larger homes, larger models are available and multiple thermal batteries can be linked to provide heating.
Bissell says that it can be used in conjunction with a gas boiler, for example, to run the hot water and the household’s radiators. However, he sees thermal batteries as ultimately a replacement for combi boilers. His argument is that the UK is transitioning away from its decades-long love affair with natural gas.
As the country deploys more and more renewable generating assets, thermal batteries offer a way of massively reducing the UK’s carbon footprint. Gas may be a lot cleaner than coal or oil for heating purposes, but it is still a fossil fuel and cannot compete, in carbon terms, with renewable generation. Being able to store energy and simultaneously convert it to heat opens the way for the UK to get serious about its carbon goals.
“Today, even with the withdrawal of subsidies and grants for solar panels, there are some 850,000 homes in the UK that have solar panels and more are being installed all the time. Harvesting that energy and using it for baths and showers, or to drive the radiators in winter, creates immediate savings if you have thermal batteries installed,” he notes.
Sunamp began its product development with household hot water and heating requirements in mind, because that was a large scale, readily addressable market. However, it is now hard at work on its commercial scale batteries. “We have a number of commercial and industrial companies that are very interested in this technology, and that has given us a huge pipeline of commercial projects that we are about to service,” he says.
Sunamp’s prototype pallet-sized thermal batteries can store some 80 kilowatt hours of heat energy, or the equivalent of a 2,000 litre hot water tank. As such it is ideal for supermarkets and other significantly sized commercial establishments. The first project, a heating battery used to optimise the CHP system at Wirral Metropolitan College, is just about due for installation.
The company is also developing a container sized battery system capable of storing some two megawatt hours of heat, in a 20-foot container.
“We have also devised a thermal battery system capable of storing heat at high temperatures between 120 and 250°C for companies whose operations require process heat. The range of possible applications is truly breathtaking,” Bissell concludes.
Source : HeraldScotland