Hydrothermal processing
| Technology | |
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| Technology details | |
| Name: | Hydrothermal processing |
| Category: | Conversion (Thermochemical processes and technologies) |
| Feedstock: | Feedstocks with high moisture content. Food waste, Garden and park waste |
| Product: | Bio-crude, syngas, hydrochar |
Hydrothermal processing, also known as Hydrothermal Upgrading (HTU), is a thermochemical conversion process that is used to convert biomass into valuable products or biofuel. The process is usually performed in water at 250-374°C under pressures of 4-22 MPa. The biomass is degraded into small components in water. Based on the target products, which are bio-crude, syngas or hydrochar, the process conditions (e.g., temperature, pressure and residence time) are chosen. One of the most important advantages of hydrothermal processing is that it can use biomass with high moisture content withouth the need for pre-drying. Hydrothermal processing can be divided into three separate processes, depending on the severity of the operating conditions. These include hydrothermal carbonisation (HTC), hydrothermal liquefaction (HTL), and hydrothermal gasification (HTG).
Feedstock
Origin and composition
Feedstocks with high moisture content are particularly suitable for hydrothermal processing and include feedstocks such as anaerobic digestion digestate, manures, sewage sludge, DDGS, food waste, municipal wastes, and aquatic biomass such as micro- and macroalgae. Hydrothermal processing routes can typically feed slurries up to 30 wt.% solids.
Pre-treatment
Process and technologies
Process
A hydrothermal process is usually performed in water at 250-374°C under a pressure of 4-22 MPa. The process can also be carried out under self-generated pressure. The hydrothermal process is divided into two reaction conditions, namely subcritical and supercritical water conditions. These two conditions are determined by the critical point of water (i.e., 374°C and 22.1 MPa). Subcritical water is classified below the critical point at a 100-374°C temperature range and under sufficient pressure to remain liquid. Supercritical water occurs when the temperature is above 374°C and the pressure is above 22.1 MPa. The decomposition steps of biomass during the hydrothermal process can be summarized as follows: at approximately 100°C, the water-soluble portion of the biomass disperses into water, and hydrolysis takes place above 150°C. Meanwhile, biomass polymers (i.e., cellulose and hemicellulose) disintegrate into their monomeric chains. At approximately 300°C and 10 MPa, liquefaction occurs and bio-oil is obtained.
Technologies
- HTC occurs at temperatures between 180°C and 250°C and pressure of 2-4 MPa. This is the mildest of the three hydrothermal processing routes. The main product of HTC is solid hydrochar.
- HTL utilises subcritical water and occurs at temperatures between 250°C and 374°C and pressures up to 18 MPa. The main product of HTL is a liquid biocrude.
- HTG or supercritical water gasification (SCWG) occurs at temperatures above 374°C and higher pressures beyond 20 MPa. The main product of HTG is a syngas.
Product
Depending on the technology, hydrochar, biocrude or syngas is produced. The produced gas is not the same as conventional syngas from gasification, which is comprised of hydrogen and carbon monoxide. Nevertheless, the gas is referred to as syngas but is typically high in either hydrogen or methane with carbon dioxide also present. The hydrochar can be utilised as fertilizers, adsorbents, and wastewater treatments. The intermediate biocrude can be further upgraded to liquid hydrocarbon fuels via catalytic hydrotreatment.
Post-treatment
Technology providers
| Company name | Country | Technology subcategory | Technology name | TRL | Capacity [kg/h] | Pressure [bar] | Temperature [°C] | Reactor | Gasifying agent | Feedstock: Food waste | Feedstock: Garden & park waste | Product: Char | Product: Oil | Product: Syngas |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Luleå University of Technology LTU | Sweden | - | Organosolv pre-treatment | 6-7 | - | 30 | 230 | Continuous organosolv reactor | - | ● | ● | |||
| Montinutra OY | Finland | - | Hydrothermal processing, pressured hot water extraction | 7 | 0.11 | - | 150-200 | - | - | ● | ||||
| TerraNova Energy GmbH | Germany | - | TerraNova ultra | 8-9 | - | 20-35 | 180-200 | Hydrothermal carbonization | - | ● | ● | ● |
Luleå University of Technology LTU
| General information | |||
| Company: | Luleå University of Technology | 
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| Country: | Sweden | ||
| Contact: | Tobias Wretborn tobias.wretborn@ltu.se | ||
| Webpage: | https://www.ltu.se/ | ||
| Technology and process details | |||
| Technology name: | Organosolv pre-treatment | Technology category: | Conversion (Thermochemical processes and technologies) |
| TRL: | 6-7 | Capacity: | 0,7 l/min (biomass) kg·h-1 |
| Gasifying agent: | not relevant | Pressure: | Up to 30 bar bar |
| Reactor: | Continuous organosolv reactor | Temperature: | Up to 230 °C °C |
| Other: | not relevant | ||
| Feedstock and product details | |||
| Feedstock: | Lignocellulosic biomass | Product: | Cellulose rich pulp, Lignin and Hemicellulose rich process liquor |
Department of Civil, Environmental and Natural Resources Engineering: Humanity faces enormous challenges in the areas of energy, environment, raw materials, water resources and security. By research and education in the areas of mining, civil and environmental engineering, we take responsibility for the development of a sustainable society. We are about 400 people of about 50 nationalities, of which 200 are doctoral students and just over 50 professors. You will find us in the T-pavilion and the C-house on the university campus in Luleå. You will find our Lab activities in the F-house and the C-house. Our research and education are characterized by a strong experimental and applied profile with several large and well-equipped laboratories. All activities are quality assured by our dedicated professors and lecturers in an exclusive and successful collaboration with industry and the public sector. 65% of our research is externally funded and we have well-developed international collaborations with universities in all continents.
Montinutra Ltd. (Boreal Bioproducts™)
| General information | |||
| Company: | Montinutra Ltd. (Boreal Bioproducts™) | 
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| Country: | Finland | ||
| Contact: | Jaakko Pajunen, Managing Director
Mobile: +358 44 34 35 162 Email: firstname(at)borealbioproducts.com | ||
| Webpage: | https://www.borealbioproducts.com | ||
| Technology and process details | |||
| Technology name: | Hydrothermal processing, pressured hot water extraction | Technology category: | Conversion (Thermochemical processes and technologies) |
| TRL: | 7 | Capacity: | 1 metric ton per year kg·h-1 |
| Gasifying agent: | not relevant | Pressure: | disclosed on demand bar |
| Reactor: | not relevant | Temperature: | 150-200 °C |
| Other: | not relevant | ||
| Feedstock and product details | |||
| Feedstock: | woody biomass, forest industry side stream, sawdust, spruce | Product: | - SpruceSugar (a galactoglucomannan rich pressurised hot water extract);
- thermally treated wood for biocomposites, or furniture, or MDF; - lignin extract - other on demand |
Montinutra Ltd. (Boreal Bioproducts™) produces high value bioactive products from forest industry side streams. Our mission is to convert forest industry side streams into valuable ingredients for the cosmetics, food & beverage and chemical industries with our scalable technology. Montinutra Ltd. (Boreal Bioproducts™) has strong research and innovation background and a solid patent portfolio in key markets globally.
Roadmap: we are currently operating in pilot-scale. Our operation in Turku, Finland have capability and knowhow to extract high value bioactive compounds out of sawdust. Preparing to build industrial scale operation in 2026-2027 that will produce sustainable and ethical SpruceSugar™ extract from sawdust. Sawmills produce millions of tons of sawdust and bark globally. Current commercial value of these side streams is low. Montinutra Ltd. (Boreal Bioproducts™) can add significant value by extracting high value bioactive compounds from those low value side streams. Sawdust and bark are usually incinerated in bio-power plants and the economic value add remains low, in addition to which the burning process causes greenhouse gas emissions.
TerraNova Energy GmbH
| General information | |||
| Company: | Terranova Energy GmbH |
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| Country: | Germany | ||
| Contact: | info@terranova-energy.com | ||
| Webpage: | https://www.terranova-energy.com/en/ | ||
| Technology and process details | |||
| Technology name: | TerraNova ultra | Technology category: | Conversion (Thermochemical processes and technologies) |
| TRL: | 8-9 | Capacity: | kg·h-1 |
| Gasifying agent: | Pressure: | 20 - 35 bar | |
| Reactor: | Hydrothermal carbonization | Temperature: | 180 - 200 °C |
| Other: | |||
| Feedstock and product details | |||
| Feedstock: | Dewatered sewage sludge or shredded biowaste with a dry matter content of 5-30% | Product: | biocoal; carbon-rich process water (by-product) |
TerraNova Energy is a pioneer in Hydrothermal Carbonization of sludge and biowaste. In 2010, TerraNova Energy constructed the first HTC demonstration plant in Europe, and subsequently, constructed the first commercial HTC plant worldwide in 2016. The advantage of the TerraNova ultra process is that it takes place in an aqueous environment, so that no drying of the input material is necessary. Furthermore, the TerraNova ultra units have a highly efficient recovery system, which minimizes the heat demand of the HTC process. The HTC coal contains hardly any water and, thanks to its high energy content, can be used for climate-friendly energy generation in coal-fired power plants or as a substitute for fossil fuels in cement plants or waste incineration plants.
Open access pilot and demo facility providers
Patents
Currently no patents have been identified.