Dr. Iisa obtained her MSc (with excellence) in Chemical Engineering from Helsinki University of Technology in 1983 and her PhD (with honors) from Abo Akademi University in Finland in 1993. After receiving her PhD she joined the Chemical Engineering Faculty at Oregon State University as Assistant professor. In 1997 she moved to the Institute of Paper Science and Technology where she became Associate Professor in 2000. From 2001 to 2003 she worked in the Inorganic Environmental Research Group at Chalmers University of Technology in Gothenburg , Sweden . She is currently Principal Research Engineer at the Institute of Paper Science and Technology with research focus on the forest biorefinery.

Research Summary

Dr. Iisa's research field encompasses combustion and gasification chemistry and gas purification and air pollution control issues. In the pulp and paper field, she has recently studied the kinetics and release of inorganic species (sulfur, alkali metal, chlorine, nitrogen, and heavy metals) during black liquor devolatilization, combustion and gasification, and she has worked extensively on nitrogen oxide emissions and heavy metals emissions from recovery boilers. Other important research areas include sulfur removal from pressurized combustion and gasification systems as well as alkali metal and heavy metal capture from fossil and biofuel combustion. Dr. Iisa's current research focus is on the development of viable forest biorefineries.

Fuels, chemicals and/or energy can be produced from woody biomass in Forest Biorefineries that are integrated into pulp and paper mills. Currently about 40-60% of the biomass wood source at pulp mills is converted to paper and board products and the residual is converted to a low value fuel that is burnt in recovery boilers or hog fuel boilers. In forest biorefineries, the remainder of the wood is utilized to produce high value energy, fuels, or chemicals. There are two main platforms for biorefineries in pulp mills: a) extraction of hemicelluloses prior to pulping and subsequent conversion to products such as ethanol, and b) production of energy, fuels or chemicals via black liquor derived syngas. A forest biorefinery that combines both platforms is illustrated in Figure 1.

Figure 1. Block diagram of an integrated wood based biorefinery

In this concept debarked woodchips are extracted for hemicelluloses prior to pulping, and the sugars are fermented to fuel grade ethanol. Black liquor from the pulping process is gasified and the syngas from gasification is used for the production of fuels, chemicals, or electrical energy. Additional biomass may be added to the gasifier to increase the production of fuels or chemicals.

The integration of biorefineries into pulp mills offers several synergetic advantages compared to stand-alone biorefineries. The existing infrastructure for biomass collection, handling, and processing at the mill can be utilized in the biorefinery, and low level energy produced in the biorefineries can be used in the mills. These can translate into considerable savings. The cost of methanol production from biomass when integrated into a pulp and paper mill has been estimated to result in 20% lower costs for the fuel production compared to a stand-alone biomass-based methanol production plant (Ohlstrom et al., 2001).

For pulp mills, biorefineries bring a possibility to convert more of the raw material into products and increase the profitability of the mills. It is envisioned that in the US forest industry it is possible to produce 1.9 billion gallons ethanol and 600 million gallons of acetic acid by extracting hemicelluloses prior to pulping. Black liquor gasification could potentially produce 116 million BOE electrical energy or 10⁹ million barrels of liquid fuels and chemicals.

Dr. Iisa's research in the forest biorefinery area addresses issues of mill integration related to producing fuels and energy via black liquor gasification. These include studies of black liquor gasification kinetics under pressurized conditions, evaluation of pulping chemical recovery and gas purification methods for black liquor gasification, and regeneration of liquors from advanced pulping processes.