Synthetic Coal

Synthetic Coal

Sun coal has re-discovered a process of converting green biomass into coal.

It combines biomass with water./steam at 200oC at 20 bars for a few hours.


The CarboREN® Process in Detail

Receiving and Storage

Before being treated, delivered organic waste is stored depending on composition. Storage in a CarbonREN® plant is designed for automatic loading on nights or weekends.

Controlled Crushing, Filtering and Washing
The biomass is crushed and reduced to a grain size of 60 mm and filtered to remove impurities such as stones, metal or plastic. Accumulated waste can either be processed later or disposed of.

Hydrothermal Carbonization (HTC)

In just a few hours, temperatures of 200°C and pressure of 20 bars completely breaks down the structure of the biomass and separates out the water. The resulting HTC-slurry is then removed from the cooker, „de-stressed“ through ambient pressure and cooled.

Mechanical Dewatering

During mechanical dewatering the water content of the HTC-slurry is reduced by 50% by a press. The separated water is mostly re-circulated in the process.

Thermal Drying

The HTC-cake is dried, reducing the water content to less than 5%. Surplus heat from existing plants or existing local or district heating can further increase the economic feasibility. Wastewater produced by the process can either be re-ciculated to a treatment plant or treated in the plant itself.


The resulting biocoal can be processed into SunCoal® powder, SunCoal granules or SunCoal pellets, according to customer specification, for stored, further refined (for example, into gaseous fuel or syngas), or used directly as fuel. 

Hydrothermal Carbonization to produce coal

Animation of process