The Green Soul heat storage system makes heating decentralized and emission-free

By Hildegard Suntinger

Dr. Bernhard König’s vision is to use solar energy from the summer as a heat source in the winter without burdening the planet. SoulHeat, the heat storage system he developed, is designed to make this possible. It has the capacity to store energy from photovoltaic and solar thermal systems without loss over the long term and can meet heating needs without significant ongoing costs. This could ultimately also make homeowners independent of energy suppliers. In this episode of the Start-up-of-the-Day series, König talks about his innovation and the challenges of starting up a company:

Can you describe the SoulHeat heat storage system?

With our infrastructure-independent heat storage system, heating needs can be met for years without significant ongoing costs. This means that the high uncertainty regarding energy source costs can be almost completely eliminated with a one-time investment. There is only minimal electricity consumption by the circulating pumps.
SoulHeat can be freely scaled to the customer’s desired storage size, ranging from under one hundred kilowatt hours (kWh) to tens of thousands of kWh of storage capacity. The unit can be buried in the garden as well as fit in unused basements, as it requires only a few pipes. The one-time investment for the heat accumulator ranges from €7-16 per kWh of storage capacity. The price decreases with the size of the device. Compared to electricity storage units, whose price ranges from €400 to 1,000 per kWh, it has an enormous price advantage.

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What problem are you solving and why is that important?

With our solution, we make the energy from photovoltaic and solar thermal systems usable and make their owners independent of energy suppliers. In addition, our solution is emission-free and has a low power requirement. Due to the low operating costs, it can be used by many and make a major contribution to an environmentally friendly energy supply.

The low power requirement can also relieve the burden on the power grids. This is important since phasing out fossil energy is associated with enormous power consumption.

Was there a moment when you wanted to give up?

Start-ups face the challenge of having to put a lot of effort into many areas. It starts with the technology itself. There is no such thing as the perfect solution, and a certain compromise must always be found between various factors. No sooner has this been achieved than the first financial hurdles arise. We are very happy to have access to a really good network of funding opportunities in Austria. As a hardware-intensive startup, however, the search for suitable investors will probably be challenging.

Of course, there are always setbacks in all areas of a business, but that’s exactly what makes it exciting. So far, we haven’t thought about giving up and are looking to the future with confidence.

What achievements have made you really proud?

Since I am a technician, the successful proof-of-concept at the lab scale was one of the most joyful moments for me so far. You spend a long time developing an idea time without knowing exactly whether you’ve considered everything and whether the whole thing will actually work. But it’s also very motivating that so many potential customers are coming forward and showing interest in the project.

Was it difficult to get financing?

I financed the first time with savings. Later, I received funding, first from the tech2b incubator and then from the state of Upper Austria. The applications take some time, but you are not left alone.

Where would you like to be with Green Soul in five years?

In five years, we want to have already made emission-free heating possible for many people with their own homes – and another order of magnitude, namely the use of SoulHeat for local heating networks, as these are increasingly being operated in small settlements, to cover local heating requirements in a decentralized manner.

What makes your heat storage better/different than existing ones?

The current market offer for heat storage systems is mainly focused on water, ground and sorption-based systems. Sorption-based systems include, for example, the conversion of biogas into electricity., whereby the latter are often still in the research stage. Compared to these systems, SoulHeat has a high degree of innovation. Our solution is based on a thermochemical process that is reversible.

As such, it outperforms the currently dominant sensible heat storage systems such as hot water tanks by at least a factor of three in terms of power density. This high-temperature level coupled with SoulHeat’s modular design makes it possible to convert even old buildings that are difficult to heat to ecologically clean heating energy.

The system’s complete reversibility means that it can be recharged and discharged again and again without sacrificing performance. SoulHeat is therefore a one-time investment that lasts for decades.

In addition to being used as a complete heating system, SoulHeat can also be combined with air source heat pumps as a small storage tank. The main sales criterion in the rapidly growing market for air-source heat pumps is the annual performance factor, i.e., the efficiency value calculated over one year. But it turns out that air heat pumps are inefficient during the cold season., but a small SoulHeat storage tank can significantly increase its efficiency. Depending on the design, the efficiency increase can range from COP 2.5 to COP 8 (note: COP stands for Coefficient of Performance and refers to the coefficient of performance).

Are you hiring?

We will increase our team after a successful prototype evaluation. We will be looking for technically talented people for research and development (R&D) who want to make a difference with their work. In mid-2023, we will also build up sales, production, marketing and administration and will look for personnel accordingly. That means we can use quite a few people with a solid work ethic.

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