Hydrothermal carbonization is a process in which biomass is heated in water under pressure to create a char product. With higher plants, the chemistry of the process derives primarily from lignin, cellulose and hemicellulose components. In contrast, green and blue-green microalgae are not lignocellulosic in composition, and the chemistry is entirely different, involving proteins, lipids and carbohydrates (generally not cellulose). Employing relatively moderate conditions of temperature (ca. 200 °C), time (<1 h) and pressure (<2 MPa), microalgae can be converted in an energy efficient manner into an algal char product that is of bituminous coal quality. Potential uses for the product include creation of synthesis gas and conversion into industrial chemicals and gasoline; application as a soil nutrient amendment; and as a carbon neutral supplement to natural coal for generation of electrical power.
Bibliographical noteFunding Information:
Financial assistance was provided by the BioTechnology Institute of the University of Minnesota and the Initiative for Renewable Energy and the Environment (IREE) and is gratefully acknowledged. Dr. Kannan Seshadri of 3M is also thanked for plotting the data of the designed experiment.
- Algal coal
- Hydrothermal carbonization
- Synthetic coal