Carbon mitigation using biomass gasification to displace natural gas, during sponge iron powder production

Abstract: Carbon dioxide is one of the green house gases that cause climate changes. Both the European Union and the Swedish government have the goal to reduce the emission of green house gases. The first aim of this project was to calculate the amount of the total emissions when producing Sponge Iron powder at Höganäs for both upstream and process. The calculations showed an emission of 234, 2 k ton per year. The second aim was to calculate the carbon dioxide emissions when using biomass compared to natural gas in the belt furnace. The results showed that there could be made a 4% decrease in emission rates when using biomass. The third aim was to calculate the economical difference between biomass and natural gas as a fuel. After 10 years the using a biomass mix (30% is fiber sludge and the rest 70 % is wood residues) the payback time was reached, considering reduced need of emission allowances (124. 5 €/ton CO2 equivalents), an upfront investment of 13 MSEK, and a 5% depreciation each year .Using the same calculation, but with a higher cost for emission allowances, the payback time was reduced to 2-3 years depending on raw biomass. The fourth aim was to look at emission of other polluting substances and compare the difference between using natural gas versus biomass. Although carbon dioxide levels could be cut by 4% per year other substances emission levels will be higher because of the gasification process, especially NOx and mercury. Further investigation has to be done in order to understand how to manage a increased amount of other substances.