Heat 2 Power:
New Thermo Storage Technology []

Competitor product 1: Concrete storage

The storage consists of a bundle of horizontally arranged heat exchanger cylinders made of special concrete with a diameter of approx. 25 cm. Inside each cylinder are 2 parallel U-shaped steel tubes. To extract the stored heat, the direction of flow is reversed. A 20ft module can store up to 1.5 MWh.

Advantages:

• Simple modular construction

Disadvantages:

• Limited temperature range up to 400°C, therefore mainly intended for generating process heat
• To generate electricity, it is necessary to decouple heat to a second medium
• No continuous operation, but change between "in - out"
• Heat in the returning fluid flow cannot be used to generate electricity

Competitor product 2: lava rock storage

A container houses a bed of lava rock through which hot air flows to heat it up. To extract the stored heat, the direction of flow is reversed and switched to a circuit with a steam generation system with a downstream turbine.

Manufacturer information: The stored heat can be used to generate 1.5 MW of electrical energy over a period of 24 hours via a steam turbine.

Advantages:

• Cheap storage material
• Easily scalable
• Underground installation possible

Disadvantages:

• Relatively small usable temperature range
• Gas seeks the path of least flow resistance, hence dead spaces and uneven temperature distribution
• To generate electricity, it is necessary to decouple heat to a second medium
• No continuous operation, but change between "in - out"
• Heat in the returning fluid flow cannot be used to generate electricity
• Large volume
• No constant energy output to the subsequent heat engine, since the temperature in the storage tank continuously decreases when discharging
• Dust (abrasion from bulk material) in the circulating air circuit, therefore a (high-temperature) filter is required

Competitive product 3: Metal body

Electricity that is fed in is converted into heat via a resistance heater, which then reaches the storage core made of steel elements via a gas circuit. The stored heat reaches a heat exchanger via the same gas circuit, which feeds out process heat or process steam.

Advantages:

• High storage density
• Expensive storage material that retains its value
• Modular construction

Disadvantages:

• Limited temperature range, therefore mainly usable as heat supplier. Larger systems can also produce electricity.
• To generate electricity, it is necessary to decouple heat to a second medium
• Heat in the returning fluid flow cannot be used to generate electricity
• No constant energy output to the subsequent heat engine, since the temperature in the storage tank continuously decreases when discharging

Competitor product 4: Granulate storage

Hot air flows through the special granules and heats up to 1300°C. To extract the stored heat, the direction of flow is reversed.

Advantages:

• High maximum storage temperature
• Modular structure
• High energy density

Disadvantages:

• Gas seeks the path of least flow resistance, hence dead spaces and uneven temperature distribution
• To generate electricity, it is necessary to decouple heat to a second medium
• No continuous operation, but change between "in - out"
• No constant energy output to the subsequent heat engine, since the temperature in the storage tank continuously decreases when discharging
• Dust (abrasion from bulk material) in the circulating air circuit, therefore a (high-temperature) filter is required

Competitor product 5: Ceramic shaped bricks

Electrical resistance heaters are located in a structured accumulation of ceramic blocks and heat them up by radiation. To extract the stored heat, there is a circulating air circuit that is used to generate steam for a turbine.

Advantages:

• Very high usable temperature range
• Continuous operation (simultaneous loading and unloading) possible

Disadvantages:

• To generate electricity, it is necessary to decouple heat to a second medium
• Electrical heating inside the storage tank, therefore no use of waste heat as heat source possible
• High flow resistance
• Complex structure
• Constant energy delivery to the subsequent heat engine is only possible with a high level of control effort or parallel reheating