Various combinations of co-firing of biofuels and fossil fuels can be used as an efficient method to rapidly introduce biofuels into existing energy systems. They also offer effective utilisation of local, small fuel resources, used mainly by larger plants. Ibis study analyses different factors and incentives that influence co-firing in bio-fuelled industrial production of steam, heat and power and case studies illustrating Sweden's experience in plants in the field. The greatest emphasis in this note is on non-technical factors that affect the incentives for co-firing. The study calls for a range of driving forces to introduce co-firing, such as technological, economic and financial factors, fuel resources and environmental matters. The results show that co-firing has been very efficient and beneficial for the economies of the companies studied. Moreover, the companies have achieved this with moderate investment costs and still have the flexibility to meet future changes in fuel prices and other market conditions. However, there are restrictions in combustion technology for co-firing. High activity in co-firing in some countries, especially in the Nordic countries, is indicated in this study. The already existing high activity in co-firing is expected to increase. New environmental legislation for recycling systems, landfill fees and international agreements to lower emissions of greenhouse gases will increase the supply of different fibres and fuels that can be used. This will promote the future development of co-firing. (C) 2002 Elsevier Science Ltd. All rights reserved.