A method of continuously providing a pressurized slurry of a solid material and liquid carbon dioxide is disclosed. The method comprises mixing particles of the solid material and particles of solid carbon dioxide in a mixing container and feeding the mixture of the solid material and the solid carbon dioxide to a pump to form a slurry of the solid material and liquified carbon dioxide. Within the pump, the solid carbon dioxide sublimates, forming a gaseous carbon dioxide that subsequently liquefies due to an increase in pressure. The liquid carbon dioxide and the solid material then mix to form the slurry of the solid material and the liquid carbon dioxide. In some embodiments, the pressurized slurry may be used for pipeline transportation of the solid material. A system of producing a continuous pressurized slurry of solid material and liquid carbon dioxide is also disclosed. A method of producing hydrogen is also disclosed.