Energy from straw - a comparison of some straw-burning furnaces.

Abstract Since 1974 research has been carried out in Weihenstephan on the production of energy from cereal straw. First the fuel straw was characterised by determining its calorific value, taking into consideration moisture content, storage conditions, species, varieties, growth conditions and fertilisation. Other characteristics of the straw—such as percentage of volatiles and chemical elements, demand for combustion air and specific fuel gas volume—were determined. Measurements were made with serial-furnaces (mainly the throughburning type). These furnaces were developed in order to increase efficiency and decrease emission. Automatic stoking systems had to be tested. Test runs were also carried out on prototype furnaces with both under-burner systems and hand stoking. A special under-burning furnace with a low capacity automatic charging system (for heating a domestic dwelling) had been developed in Weihenstephan. Different types of air heater, using both high pressure bales and roto bales, were constructed. Economic calculations show that straw is a cheap fuel under certain conditions. An EEC study shows the energy demand and energy production potential of straw and woodwaste in various rural areas.