Dive into the technology behind Kraftblock.

01 The energy storage system

Every energy storage is always integrated into a system that converts the three aspects of a storage cycle: Charging, Storing, Discharching. Kraftblock is a thermal energy storage, the energy going in and out of the storage is heat. For process heat, this is more efficient than storing electricity in batteries or energy in hydrogen.

The use cases for an energy storage system vary depending on when and how much energy can be charged and discharged. For example, you can shift cheap electricity to times when electricity is expensive, or use energy from sunny days at night or the next day. Waste heat from flue gases also becomes flexible when a storage is integrated. Kraftblock serves industrial processes as well as utilities and suppliers with its storage system. The Kraftblock solution can store from a few minutes to two weeks, which means that there is great flexibility in linking energy generation with supply.

Typical operation parameters of Kraftblock:

• Storage temperature between 350°C and 1,300°C
• Minimum charging/discharging power: 300kW
• Discharging at storage temperature or any other temperature smaller than that.

The benefits of a high-temperature storage are lower investment and operation costs. Due to the higher temperature the capacity of the storage is higher. This translates to less storage footprint which means less material and installation.

The operation of the Kraftblock system is also very flexible due to the modular approach. Different modules can perform different operations at the same time, such as charging, storing or discharging. This makes it possible to supply a 24/7 process with energy from storage modules that charge independently. This also means that the purchase of electricity or the amount of waste heat used is flexible and can be adapted to the best operating costs and schedule.

02 Charging and Discharging Kraftblock

As the Kraftblock storage follows a platform approach, we usually use the same storage design, independent from the application. Kraftblock can link the storage with different charging and discharging components.

In the case of waste heat, we can charge the waste heat directly. The minimum requirement additional to the minimum charging power is a temperature level of 350°C or more. Depending on the composition of the flue gas and the application, we might integrate a heat exchanger. If we use electricity as an energy source, we convert the power into heat in a resistance heater which heats air.

The hot gas is blown into the storage where the material absorbs the energy by heating up. Charging stops at a defined point and the storage cycle begins. When the heat is needed, ambient air is blown through the storage. The heat of the material is transferred to the air and the system releases the energy at the temperature level needed for the process of the customer. We discharge in a range between the maximum storage temperature down to 50°C.

A part of the system is the transfer to other heat media. The Kraftblock system can discharge heat as air, steam, gas, thermal oil, water or other transfer media, depending on your infrastructure.  Unlike batteries, a Kraftblock storage system also has no set charge/discharge ratio. While you can charge 3MW, you can discharge for example 0.5 or 7MW. This gives you more charging and discharging flexibility to manage your energy use and operating costs.

The round-trip efficiency from power to storage to process is over 95%. With waste heat, the efficiency is even higher. The storage's energy losses are minimal.

03 The Storage Material

Just as important as how we charge and discharge energy is how we store it. The material is the essential part in terms of capacity, efficiency and sustainability. Kraftblock has developed a new material with a special recipe. Much of it is a sustainable and low-cost product: up to 85% is made from upcycled materials such as steel slag. It also has a long lifetime: It was tested for 15,000 cycles with no degradation discovered. This is 50% longer than the maximum of battery storages and used once a day, Kraftblock material has a lifetime of over 40 years.

Our team developed a new material for a number of reasons:

Every solid storage material has a specific heat capacity and conductivity. These parameters cannot be changed and must be used as they are. Kraftblock has developed a material that can be easily modified and adapted to the application since it is mixed using different materials.

Most existing materials are limited to a certain temperature range. Kraftblock has developed a stable material that can withstand massive temperature drops, allowing it to be used in a wide range of applications.

Natural materials such as basalt are more or less sustainable depending on the supply chain. Artificial materials such as alumina or magnesia bricks require large amounts of energy to produce. Kraftblock has therefore developed a sustainable material using a circular economy approach, incorporating cheap materials from landfills into the recipe. Although the material can withstand temperatures of up to 1,300°C, we do not need to heat it during production.