The industrial heat sector – which includes all areas of heavy industry that require intensely high temperatures such as aluminum, steel, cement, concrete, and glass – accounts for more carbon emissions (10%) than airplanes (2%) and car exhaust fumes (6%) combined. To reach the level of heat necessary, factories need to burn a lot of fossil fuels – usually carbon-rich coke or coal.
A massive amount of this heat energy is wasted in the process. Now, if there was a way to capture the excess heat being emitted, store, and then re-use it when required, it would dramatically improve the energy efficiency of a facility, save money, and cut greenhouse gas emissions. And that’s what Norwegian startup concrete thermal battery firm EnergyNest has done by developing a modular and scalable thermal battery that can store waste heat up to weeks with minimal losses.
EnergyNest chief executive Christian Thiel told Recharge:
All industrial manufacturers that have thermal processes in place would benefit from our technology. Breweries, chemicals, pharmaceuticals, steel, aluminum, concrete, brick makers, other building manufacturers — they all operate with high-temperature heat.
Decarbonizing combined-cycle [natural gas-fired] power plants is also on our agenda, and we can offer 24-hour concentrating solar power [CSP] for 30-50% below the cost of molten-salt storage.
The thermal battery would still be useful even if fossil fuels were replaced by renewables-powered electric arc furnaces or hydrogen. It may not be needed to cut emissions, but it would help lower heating costs by reducing and recirculating waste heat.
The technology is made from abundant, non-hazardous, and recyclable geomaterials (concrete and steel) that are easy to acquire, meaning local materials and workforces can be used. Furthermore, transportation can be kept to a minimum. A majority of piping works are prefabricated and pressure tested before installation making for easy on-site assembly. All the elements that make up a module are designed for easy transportation.
The levelized cost of storage is up to 47 times cheaper than utility-scale lithium-ion storage. Plus, the battery has a lifespan of at least thirty years, but likely over fifty years. With such impressive figures, it’s no wonder the startup has made deals with companies like Eni, EDF, and Siemens.
The chief executive of Siemens Energy’s Large Rotating Equipment business unit, Jörn Schmücker, said:
Energy storage is the key to a decarbonized world. With [our] Future of Storage [program] and our cooperation with EnergyNest we are able to offer our customers exactly those solutions which help to sustainably decarbonize the industrial sector — with the strong advantage of improving the efficiency and the economics of their plants.
How It Works
- The heat energy is sent to a Thermal Battery (a six-meter-long 1.5MWth unit the size of a shipping container) via a heat transfer fluid (HTF). The module consists of looping pipes cast into the Thermal Battery elements – which are long cylinders of Heatcrete. (Heatcrete is a low-cost proprietary concrete-like material made from the mineral quartzite, with traces of cement, chemical binders, and superplasticizers.) The HTF flows through the pipes.
- Temperatures as high as to 430°C can be stored in the Heatcrete.
- To charge, hot HTF flows through the pipes from top to bottom, and thermal energy is transferred to the storage material.
- During discharge, cold HTF flows in the opposite direction, and heat exits from the top of the Thermal Battery.
Thiel explained by elaborating on one of the company’s projects at brick maker Senftenbacher’s plant in Austria:
So, for instance, at the project that we’re doing at brick maker Senftenbacher’s plant in Austria, which is a waste-heat recovery project, we tap into the excess heat generated by a kiln furnace. We install a heat exchanger near the kiln and extract the heat from the heat exchanger into a closed-loop oil system. Some small pumps circulate the hot oil and then the Heatcrete storage is really heated up. And then when we discharge at this project, the heat from the fluid activates an off-the-shelf steam generator. And the steam increases the temperature in the kiln.
Thanks to its modularity and stackable nature, projects can employ as many units as needed – from thousands required for a 24-hour gigawatt-scale CSP project to just one at a small industrial plant. Items such as electric heaters, heat exchangers, and steam generators, can be incorporated, as well as additional piping and integration work with existing facilities. Like this, it can suit every possible application. EnergyNest’s Thermal Battery is a win-win anywhere that large-scale heat is present, and a solution anywhere energy needs to be stored.
