Made in sweden

Zero Energy Hydrothermal Carbonization

Superefficient sludge handling

Presenting a revolutionary new way to convert wet sludge into biofuel


Wastewater sludge, industrial sludge, wet biomass – it's a problem that has to be dealt with. We have developed a robust industrial-strength process to convert sludge into a valuable asset called hydrochar.

We use a proven method – hydrothermal carbonization – but with several innovations to make it into what is probably the most efficient sludge disposal method for the 21st century.



Swedish Energy Agency provides €2.2M in funding

C-Green has been granted funding to develop a full-scale sludge-to-biocoal reactor in cooperation with Stora Enso. Read the Swedish or English press-release for more information.


#SET100 List 2018

C-Green has been selected as one of the best 100 start-ups working on the global energy transition. See the full list of finalists, read about the competition, and check out the jury.



Our goal is to turn hydrothermal carbonization (HTC) into a modern and cost-effective solution for almost any wet biomass sludge problem. Through innovation and modern industrial design, we believe our Zero Energy HTC solution will become the new environmental benchmark for nearly all sludge disposal problems. 


Impressive Dewatering

Go from 70-90 % water content down to 30 %, without using any external heat. It's simply the most efficient way to dry large quantities of wet biomass!


Our patented invention that changes conventional, energy-intensive HTC into a process with no need for external heat energy.


High pressure and temperature levels eliminates bacteria, fungi, and viruses. The result is an odor-less and sterilized hydrochar.


High capacity

Processes up to 10 tonnes of sludge per hour on a space equivalent to 5 parking spaces.

Making fuel

Zero Energy HTC turns wet sludge into a dry economic biofuel with excellent energy properties. It's ideal for use in a biofuel heat and power plant.


The Zero Energy HTC process is continuous, and uses our own patented FracFlow reactor design. Easy to use and better performance than traditional HTC.



This is what hydrochar looks like. Our HTC process efficiently turns wet biomass into a dry hydrochar product using a minimum of external energy. The process eliminates bacteria, fungi, and viruses, and immediately stops greenhouse gas emissions caused by organic decomposition.

Hydrochar is perfectly suited as a biofuel in a modern heat and power plant.



Dry | moisture level around 30 %.

Valuable | high-energy content equal to standard wood-based biofuels.

Sterile | hygienic, safe and easy to transport.


If you're interested in our unique HTC solution for sludge handling, or have a pressing sludge problem please don't hesitate to contact us!

For more information

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This activity has received funding from the European Institute of Innovation and Technology (EIT). This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme.