Expert Interviews

Interview: Thermal Batteries as Addition to the Current Energy Storage Market | Dr. Christian Thiel, CEO, EnergyNest

Founded in 2011 by Professor Pål Bergan, EnergyNest has focused on the development of Thermal Battery technologies. Their pilot Thermal Battery system was in 2015 installed at the Masdar Institute Solar Platform in Abu Dhabi, UAE, proving their technology’s viability. ees International talked to EnergyNest’s CEO Dr. Christian Thiel about the company’s past and future.


Dr. Christian Thiel, CEO, EnergyNest

ees International: What is the story behind the founding of EnergyNest?

Large-scale energy storage is one of the most urgent problems in the world. Seven years ago, in Norway, Professor Pål Bergan began searching for a solution; but instead of following mainstream large-scale energy storage approaches that fight complexity with complexity, using cost-intensive, high-tech solutions, he sought a response that was simple and cost-effective.

EnergyNest was born as we started to develop a modular thermal energy storage solution that is scalable, durable, easy to install and operate, and made primarily of locally-sourced materials. One such material is HEATCRETE® – our high-performance concrete for thermal energy storage, which we developed in close cooperation with HeidelbergCement. Our first patent was granted in 2012 and the first prototype successfully tested and then implemented soon after as a Thermal Battery pilot with combined capacity of 1 MWh at the Masdar Institute Solar Platform in Abu Dhabi, UAE. That capped off five years of research, development, and independent third-party validation leading to our launch to market.

ees International: With the increase of renewable energies, innovative storage options are becoming more and more important. How can EnergyNest’s Thermal Battery contribute to this changing market?

Thermal Batteries could prove to be a powerful enabling technology in helping power grids face the challenges that a move towards renewable energy sources poses. For instance, high levels of intermittent wind and solar energy can be problematic for the operation of power systems, leading to high volatility in prices and security of supply challenges. On top of this, significant amounts of renewable energy are even being curtailed due to supply and demand mismatch in some regions. This means that an efficient energy storage solution is needed to facilitate the absorption and subsequent dispatch of fluctuating renewable energy – and here, EnergyNest provides a flexible, affordable solution: Thermal Batteries can integrate energy sectors, serving the heating market by storing energy from the power market and also allowing its later withdrawal as electricity via turbines.

Our modules make up cost-effective and highly efficient Thermal Batteries that can be connected to the local grid or power generation facility and charged using excess available electric energy from renewables. This means that the stored thermal energy can be discharged in order to supply electricity back to local communities, while also providing process heat for sectors like manufacturing industries, desalination, or district heating.

It also means tapping into an otherwise wasted revenue stream: You can sell more electricity during peaks, sell less electricity during off-peak times, and cut back on heavy grid imbalance fees and capital expenditure from peaker generation. And, of course, there’s also the cost – and environmental — benefits of fossil fuel of moving away from fossil fuels by instead drawing on cheap renewable energy.

ees International: What are the pros and cons of Thermal Batteries and how does EnergyNest conquer these different challenges?

For a start, the advantage of Thermal Batteries is in the name — EnergyNests can be introduced wherever there are large amounts of underutilized heat. Electrochemical batteries such as lithium-ion and lead-acid need electricity in order to charge. So the EnergyNest thermal battery uses heat to charge up and it can be used for applications that combine heat and power — something which is not physically possible with electrochemical batteries. Since Energynest Thermal Batteries are made of simple, robust materials, they also have a significantly longer lifetime (an expected lifetime of 50+ years) and almost zero performance degradation. They primarily consist of steel and concrete, both of which are cheap and globally available commodities — in addition to being fully recyclable materials.

You can also look at it from another angle, comparing it to the established technology of molten salt thermal energy storage. Although molten salt technology is mature, EnergyNest already beats it on cost, reduced complexity, a smaller physical footprint, and environmental friendliness. So, a molten salt storage plant is essentially a very complex chemical plant, which requires a large crew of skilled personnel to operate and maintain. When compared to this and depending on the plant size, our technology reduces capital expenditure by 30-50% and operational expenditures by up to 75%.

Why? Again, EnergyNest’s solution has reduced complexity, leading to substantially lower operation and maintenance requirements, reduced parasitic energy losses, and lower price materials. Moreover, the complexity of molten salt structures only makes these financially viable for very large installations, whereas the EnergyNest storage can be competitive at much smaller scales – or scaled up if needs be.

ees International: Which customers do you want to appeal to?

Essentially, any industrial energy consumer or producer that produces very large quantities of heat, such as steam or open-cycle power plants and industrial manufacturers. Any such energy producer or industrial consumer that produces substantial amounts of heat could use this more flexibly and thus maximize the heat’s value by storing it for later use. For example, many industrial facilities have processes that are either intermittent or highly variable in their energy production and consumption.

If you use EnergyNest batteries to recover thermal energy from high-temperature waste heat sources, store it, and then later discharge this energy into downstream processes, they open up novel possibilities for waste heat recovery. Our project developers start by evaluating process data from the facility: analyzing different heat sources and heat sinks by looking at temperature, pressure, and flow rates. If we see the potential for utilizing waste heat, we can then investigate ways the EnergyNest Thermal Battery can grant industrial plant owners the optimal management of their energy use, saving both money and in some cases, reducing fossil fuel consumption and thus achieving an equivalent reduction in carbon emissions.

ees International: What are EnergyNest’s plans for the future?

Our ambition is to make large-scale energy storage a globally viable opportunity for the power and energy industries by tapping into the immense value present in the significant quantities of heat generated but lost by energy producers and consumers. By enabling customers to store this high-value heat for later use, our Thermal Battery technology gives them the flexibility to manage their energy and costs. As we move further towards a world of renewables, it will enable a more responsible use of intermittent energy, helping to balance the power grids and ensuring a clean future through making a significant contribution to active CO2 reduction.

As for immediate next steps, very shortly we will be announcing our first commercial customer, one of the top electric utilities globally. And we are looking forward to our production launch at the Mebin/ Heidelberg Cement facility in Europoort, Rotterdam Harbour. The first project we’re looking at together this new partner will involve large-scale waste-heat-recovery-and-storage for multiple open-cycle power plants.

Not only is it exciting to see this dream becoming a reality with a partner of such global standing but the value is also plain to see from their perspective – the energy storage savings from this waste heat are expected to give the project an payback time of two to five years.

Dr. Christian Thiel,


The ees International Magazine is specialized on the future-oriented market of electrical energy storage systems, not only from a technological-, but also a financial and application-oriented point-of-view. In cooperation with ees Global, the ees International Magazine informs the energy industry about current progress and the latest market innovations.