Battery using crushed rocks will make your soda more eco-friendly

Last year, Switzerland's massive 20 million kWh water battery went online, which has the equivalent of energy storage of 400,000 electric car batteries. However, not every manufacturer or nation has the natural resources conveniently located in its geography, or the patience to tunnel through hillside for 14 years before the project can begin operations.

Interesting Engineering has covered some of the alternative energy storage methods that offer smaller, yet scalable battery solutions. Some of these solutions use widely available natural resources such as sand and carbon dioxide to store renewable energy. It could one day make it possible for these solutions to be connected to the power grid, too.

Science from crushing rocks

Israel-based Brenmiller Energy is one such company working to use alternate materials for energy storage. Since 2012, the company has turned to crushed rocks to generate renewable energy used to generate zero-carbon heat.

Apart from renewable sources, the technology can also be used to trap waste heat or use biomass to generate steam, hot water, or hot air to facilitate the production of various materials ranging from paper to pharmaceuticals.

Recently, Brenmiller undertook an ambitious project by teaming up with Tempo Beverages, one of the largest beverage firms in Israel, to help the firm move away from the using fossil fuels to power its boilers.

The Tempo facility is partially owned by Heineken International B.V. and is used to make popular beverages for brands such as Heineken, Pepsi, Nestle, and Pernod Richard.

The collaboration won NIS 2.2 million (approximately USD $610,000) from the Israeli Ministry of Environmental Protection to build and install Brenmiller's bGen thermal energy storage (TES) at the facility.

The project, with a capacity of 35 MWh, will see Tempo replace its fossil-fuel-powered steam boilers. This will also add a new meaning to the term "drinking responsibly", by reducing the carbon footprint of the products made at the facility.

Interesting Engineering spoke to Avi Brenmiller, the founder and CEO of Brenmiller Energy, about its thermal energy storage system bGen, thermal energy storage (TES) in general, and how this technology will help other companies like Tempo reduce their carbon emissions.

The project is expected to be completed by the end of next year.

A former CEO at Siemens CSP ('concentrated solar power'), where he oversaw the deployment of power plants to harness solar energy, Avi Brenmiller is now leading the charge on the use of ubiquitously available material for storing vast amounts of energy.

Where did the idea for using crushed rocks for energy storage come from? 

It may seem unusual, but using crushed rocks to store energy is actually not an entirely new concept – NASA has been testing thermal energy storage (TES) technologies since the 1970s. What is new, at least for Brenmiller, is our team’s ability to apply nearly four decades of experience building, installing, and operating hundreds of MWs of solar thermal plants.

This knowledge has allowed us to optimize all aspects of our system - from design and configuration to logistics and deployment - to deliver thermal energy storage (TES) technologies that are reliable, low-cost, and economically viable at scale. 

Do the crushed rocks have to be a particular type? Or can they be locally sourced?

The storage medium inside Brenmiller’s thermal energy storage technology, known as the bGen™, is made up of crushed rocks. They can be sourced cleanly and ethically in practically any region of the world and are abundant and safe.

The use of raw materials as ubiquitous as rocks is very intentional. It helps support a circular economy and localizes our supply chains as we grow, expand, and establish additional manufacturing facilities in markets where there’s significant demand for TES technologies. 

How is renewable energy converted into heat and then returned to make steam? 

The bGen™ can discharge heat on demand to provide industrial manufacturers with 24/7 thermal energy. When the module charges, renewable or low-carbon energy that is generated on-site or from the grid is pipped through electric heaters embedded inside the TES system that convert the electricity into heat at over 99 percent efficiency. This is done when electricity prices are low or negative during off-peak hours. 

At the same time, or hours later when the module is discharging, the accumulated thermal energy is released, heats pressurized water, and generates steam.

The bGen also analyzes energy supply and demand and price data, along with information pertaining to our customers’ unique heat requirements, and dispatches steam accordingly.

Since heat dissipates quickly, what measures have been put in place to avoid energy loss? 

The bGen™ features an insulated, modular design to minimize energy losses throughout the process. It also operates at much higher temperatures than industrial plants require to provide an additional buffer. 

What is the steam production capacity that will be achieved by the project?

The project at the Tempo facility is expected to have up to 35 MWh of energy storage capacity and produce up to 14 tons of steam per hour by using electricity and replacing boilers that operate on heavy oil.

Up to what temperatures can the system be used? Are there higher-temperature applications of the technology that the company has demonstrated? 

The bGen™ can reach up to 750°C/1400°F and discharge steam, hot water, or hot air at temperatures of around 500°C/1000°F, which are more than sufficient to meet the demand of low- and medium-temperature industrial processes, including the production of paper, pulp, and plastics, and chemical and pharmaceutical manufacturing, in addition to food and beverages. 

What are the advantages of using a crushed rock battery over conventional battery types?

Unlike conventional batteries, our innovative “crushed rock battery” turns electricity into steam, hot water, or hot air to deliver heat for industrial processes. This is critically important because industrial heating and energy combustion account for 45 percent of all energy-related emissions.

Decarbonizing heat is necessary for moving the clean economy forward, and the bGen™ offers a market-ready and cost-effective solution. 

Is there a loss of performance that a user has to contend with?

Brenmiller’s bGen™ system converts electricity to heat at over 99 percent and operates at overall 97 percent efficiency.