March 31, 2023

PNNL Announces Hydrothermal Liquefaction Innovation

Breakthrough technology promises increased reliability for biomass-to-oil conversion 

3D render of the hydrothermal liquefaction system (HTL)

The novel heat recovery component of the hydrothermal liquefaction system (HTL), shown in this 3-D drawing, has the potential to enable HTL deployment. 

(Image: Pacific Northwest National Laboratory)

Pacific Northwest National Laboratory (PNNL) researchers have developed a hydrothermal liquefaction (HTL) system that boosts the reliability and commercial viability of the promising technology, which converts wet wastes into crude-like oil. The technology is now available for licensing, and PNNL is seeking collaboration and commercialization opportunities with commercial entities.

This PNNL innovation uses steam to recover heat from the high-temperature reactor effluent in the HTL process, substantially reducing the propensity for fouling and potentially reducing costs. By maximizing heat recovery using steam while eliminating the numerous heat-transfer surfaces associated with conventional heat-transfer equipment, this system offers an effective solution for HTL robustness and reliability.

"The elimination of heat exchangers in the first stage of sludge heating is transformative for the HTL process," said Michael Thorson, a PNNL chemical engineer who led the development of the technology. "Our invention has the potential to significantly reduce the risk of fouling, decrease maintenance requirements, and improve overall process reliability. This could result in a high-performing, cost-effective system essential for making HTL commercially competitive."

This new method improves the HTL process, making it more commercially viable and environmentally friendly. The innovation, called Flashing for Low-fouling, Steam-based Heat recovery in Hydrothermal Liquefaction (FLASH-HTL), is now available for commercial licensing.

Thorson said researchers hope the development will add to the array of sustainable energy solutions, many of which are under development at PNNL.

Flash steam is the key to the invention. Flash steam is low-pressure steam created when hot water is released from a high pressure to a lower pressure within a steam system. For example, it can be released through a steam trap or from boiler blowdown. Specifically for HTL and this invention, a valve reduces pressure in the reactor effluent, creating a flash steam that heats the reactor feed stream. By conducting the pressure letdown in multiple stages, this method maximizes heat recovery while avoiding the need for traditional heat exchangers.

For more information about this technology and collaboration or commercialization opportunities, please email and reference Battelle IPIDs 32588-E, “Hydrothermal Liquefaction Heat Recovery Process.”

This work was supported by the Energy Efficiency and Renewable Energy Bioenergy Technologies Office