Gasified biomass halves IGCC carbon emissions

Biomass can slash CO2 emissions by almost 50% when co-gasified with coal in an integrated gasification combined cycle (IGCC) energy plant. This is according to a team of researchers from the Universita degli Studi di Salerno in Italy.

The researchers carried out a study at the Elcogas-owned 335MW Puertollanco IGCC plant in Spain, which typically runs on a 50/50 blend of coal and petroleum coke, to examine the impact on process performance of biomass co-gasification.

Two varieties of biomass were tested: olive husks and grape seed meal, with varying amounts of each biomass added to samples of the plant's usual fuel mixture and gasified in the IGCC plant. Findings showed that the composition of syngas generated with low levels of gasified biomass (up to 4%) was practically the same as that produced from coal and petcoke alone.

However, using a computer model of the plant which was calibrated with real industrial data, the team then experimented with biomass quantities up to 60% and found that plant CO2 emissions fell (by as much as 46%) as the percentage of biomass was increased.

The power output of the plant decreased by up to 19% with grape seed meal and 14% for olive husks as the concentration of biomass rose. This, according to the team, is directly proportional to the lower heating value of biomass compared to fossil fuels. The net efficiency of the plant, which takes into account the heating value, was virtually unaffected.