A method for making a biosludge-based biomass fuel includes: introducing an oxidizing agent gas and an aqueous solution into a biosludge to undergo lysis of bacteria contained in a biosludge under oscillation of the oxidizing agent gas and the aqueous solution so as to form a pre-treated biosludge mixture; filtering out the oxidized biosludge from the pre-treated biosludge mixture under pressurized treatment to form biosludge solids; drying the biosludge solids; grinding the dried biosludge solids to form particulate biosludge solids; and mixing the particulate biosludge solids with an oil sludge.

Some variations provide a carbon-negative carbon product that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative carbon product, wherein the carbon-negative carbon product contains at least about 50 wt % carbon. In some embodiments, the carbon intensity is less than 500 kg CO.sub.2e per metric ton of the carbon-negative carbon product. Other variations provide a carbon-negative metal product (e.g., a steel product) that is characterized by a carbon intensity less than 0 kg CO.sub.2e per metric ton of the carbon-negative metal product, wherein the metal product contains from 50 wt % to 100 wt % of one or more metals and optionally one or more alloying elements. In some embodiments, the carbon-negative metal product is characterized by a carbon intensity less than 200 kg CO.sub.2e per metric ton of the carbon-negative metal product. The carbon-negative metal product can contain a wide variety of metals.

The present disclosure is directed to fuel compositions comprising a polar based continuous phase comprising a liquid ammonia with a concentration greater than about 81% by v/v of total polar phase; and a non-polar based discontinuous phase comprising one or more of a frozen hydrocarbon, a viscous liquid hydrocarbon, and a liquefied volatile hydrocarbon, wherein the fuel composition has a droplet size ranging from about 100 nm to about 250 m. Further, the disclosure provides for systems and methods for using the fuel compositions.