Biofuels that are produced through hydrothermal liquefaction are carbon neutral, meaning that there are no net carbon emissions produced when burning the biofuel. The plant materials used to produce bio-oils use photosynthesis to grow, and as such consume carbon dioxide from the atmosphere. The burning of the biofuels produced releases carbon dioxide into the atmosphere, but is nearly completely offset by the carbon dioxide consumed from growing the plants, resulting in a release of only 15-18 g of CO per kWh of energy produced. This is substantially lower than the releases rate of fossil fuel technologies, which can range from releases of 955 g/kWh (coal), 813 g/kWh (oil), and 446 g/kWh (natural gas). Recently, Steeper Energy announced that the carbon intensity (CI) of its Hydrofaction™ oil is 15 COeq/MJ according to [http://www.ghgenius.ca/ GHGenius model] (version 4.03a), while diesel fuel is 93.55 COeq/MJ.
Hydrothermal liquefaction is a clean process that doesn't produce harmful compounds, such as ammonia, NO, or SO. Instead the heteroatoms, including nitrogen, sulfur, and chlorine, are converted into harmless byproducts such as N and inorganic acids that can be neutralized with bases.