System analysis of hydrogen production from gasified black liquor

Abstract

Hydrogen produced from renewable biofuel is both clean and CO 2 neutral. This paper evaluates energy and net CO 2 emissions consequences of integration of hydrogen production from gasified black liquor in a chemical pulp mill. A model of hydrogen production from gasified black liquor was developed and integration possibilities with the pulp mill's energy system were evaluated in order to maximize energy recovery. The potential hydrogen production is 59 000 tonnes per year if integrated with the KAM reference market pulp mill producing 630 000 Air dried tonnes (ADt) pulp/year. Changes of net CO 2 emissions associated with modified mill electric power balance, biofuel import and end usage of the produced hydrogen are presented and compared with other uses of gasified black liquor such as electricity production and methanol production. Hydrogen production will result in the greatest reduction of net CO 2 emissions and could reduce the Swedish CO 2 emissions by 8% if implemented in all chemical market pulp mills. The associated increases of biofuel and electric power consumption are 5% and 1.7%, respectively.