SHAM - a simulation model for designing straw fuel delivery systems. Part 2. model applications

A dynamic simulation model for designing straw fuel delivery systems, calle d SHAM (Straw HAndling Model), has been used to evaluate the performance, c osts and energy needs of various straw handling systems. The prerequisites of straw harvest were investigated for three Swedish regions with different climatic and geographical conditions. As a fuel in district heating plants , the simulations showed that straw has the best opportunity of becoming ec onomically competitive in agricultural districts in south Sweden. The simul ations demonstrated, however, that the costs can be lowered and the system performance increased for these places by using appropriate management stra tegies. SHAM was also used to determine the number of machines in the handl ing operations in order to minimize the total fuel costs for a straw- and o il-fired district heating plant. The optimizations showed that straw can be delivered to the plant at a cost of 29.9 SEK GJ(-1) Finally, two alternati ves to the conventional high-density baler systems were evaluated; systems based on compact rolls and systems based on chopped straw stored outdoors. Tt was demonstrated that these technologies cost about 5-20% more compared with high-density bales. However, their prospects of becoming competitive h arvest methods for the future are good. (C) 1999 Elsevier Science Ltd. All rights reserved.