Development of new sod peat production technology in Finland

Sod peat is produced by cutting peat from the peat land to a depth of 30-50 cm by cutting disc or screw. Cut peat is macerated mechanically and extruded into sods or strips and dried on the production field. The share of sod peat production is less than 10% of energy peat production volume in Finland. Sod peat is used for energy in power plants, heating plants and in individual buildings. It is also used for space heating on farms, in greenhouses and in residential buildings. Nowadays, the main focus of the development is on peat production technologies that are less dependent on weather conditions and technologies that can decrease the water load in water systems. The new multi-layer sod peat drying method, being developed by SampoTech Oy and VTT in 2009 and 2010, is one method by which the independence of weather conditions in peat production could be increased. Also special machines have been developed for the new multi-layer drying method. In this method the main idea is to dry several sod peat production cycles partly at the same time without turning and windrowing the produced sod peat. The first sod layer is extracted and spread on the shaped and compressed field surface, e.g. at the centre of a strip. When the first sod layer is dry enough, it will be covered with a new sod layer. When the mean moisture content of the sod layer is about 60 w-%, a new harvest can be spread on the earlier layer. The procedure continues this way during the whole harvest season. In the new method the effect of rain on drying process will diminish because of the formation of drying base and the layered drying. The target is to produce at least 10 sod peat cycles in summer instead of two - three cycles with a current sod peat production method. The new harvesting method offers several advantages. It diminishes working-phases and equipment investment costs and thus lowers production costs and increases the quality of the energy sod peat. Obviously the most important advantage is the multiple production cycle and the ability to deliver larger quantities of energy sod peat.