Esa Vakkilainen works currently at Lappeenranta University of Technology as professor of sustainable energy systems. His professional career started in the 80s as assistant professor of Power plants teaching and researching furnace heat transfer, optimization of combined cycle processes, district heating (a Finnish specialty) and combustion of biofuels. After four years of academics Esa Vakkilainen joined A. Ahlstrom Corporation and started working at their Varkaus Boiler works. He was responsible for developing a new generation of dimensioning programs for steam generator thermal design. It was time of extensive development as circulating fluidized beds were making their way to the mainstream of steam power plants. After several changes of ownership these boilers are now manufactured by the AMEC Foster Wheeler Corporation. In addition to CFB Esa Vakkilainen has been involved with biomass boilers such as Kraft recovery boilers as Research Manager and Technical Manager. His main interests have been fouling of heat transfer surfaces, fuel delivery, air distribution and combustion. Before his current position Esa Vakkilainen was employed by Jaakko Pöyry Oy, International consultants to pulp and paper as leading technology expert – energy and environment. He has thus been involved with majority of recent worldwide purchases of biomass boilers for pulp and paper industry. Esa Vakkilainen has pursued active research which has led to supervision of about 200 M.Sc. and several Ph.D. theses. Esa Vakkilainen has lectured on boilers in technical conferences at all major continents.