Biofuel potential of Rushes. Scope Potential of rush as a biofuel Determine calorific value Compare...
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Biofuel potential of Rushes Slide 2 Scope Potential of rush as a biofuel Determine calorific value Compare with available alternatives Slide 3 Juncus effusus Juncus family - Approx. 300 spp worldwide J effusus habitats are diverse moist areas at forest margins, wet grasslands, wetland margins lake shores river banks wet meadows Some bog Slide 4 Soft Rush Moderate amount of research on Juncus spp in Ireland Slightly surprising given label as agricultural weed Might suggest that issues concerning soft rushes are minimal or have been solved Slide 5 In Ireland Broad distribution in Ireland In many areas, with poorer soils, some fields almost completely covered Some work to reclaim peat soils for agricultural use in Mayo in 2001 but soft rush invaded and became dominant Slide 6 Biology Hab prefs previously covered Rhizome permits vegetative growth producing new shoots and also reproduces by flowering www.irishwildflowers.ie Slide 7 Biology Rhizome grows at about 2cm per year Can send adventitious roots up to 50cm below surface, commonly 20cm Growth of roots and shoots accelerates from March onwards flowers June/July/August Slide 8 Growth Growth reaches a maximum in the summer and is generally positively correlated with seasonal climatic factors, and negatively correlated with standing - dead biomass parameters Slide 9 Growth Produces very high numbers of seeds - estimated at 4 milion per square metre But seeds represent tiny fraction of biomass produced annually (0.27%) Soil seedbank remains viable and provides for events such as flooding Slide 10 Control Undesirable aspects of soft rush growth not a recent problem. Classified as a weed as it is unpalatable to stock and low feed value It is well known as an agricultural Soft rush is quite resilient, not normally eaten by stock, but they will at high densities Soft rush resistant to grazing pressure, trampling and annual cutting Slide 11 Control Hydrologic conditions that favour the development of rush stands will not change with control methods such as: Cutting Herbicides Grazing Common to drain and cut or cut and spray Slide 12 Effects of cutting Research in 1939 - two cuts in two consecutive years produced an 80% reduction in shoot numbers This work also stated that it was important to have first cut in July before and after was less effective at control Work in 1936 suggested that rushes seemed to be most susceptible to weakening if cut shortly after mid - summer. Others noted that some rush species do not flourish at sites where hay is cut annually fields cut for hay year after year. Trials in 1964 found that mowing repeatedly 46 times per year was required to control the rushes but would not eliminate them. Slide 13 Effects of cutting 1995 work suggested that cutting to half their height had no effect Cutting to ground level twice a year over two years effective at controlling them Most control methods in use in Ireland involve herbicides in combination with cutting or drainage depending on land use Slide 14 Energy Content Determined moisture content 5 size classes of rush 20 30 cm 30 40 cm 40 50 cm 50 60 cm >60cm Slide 15 Moisture content Length classNumber of rushesMean lengthWet mass(g)Dry Mass% Moisture 20-30cm1225.464.353.0130.72 30-40cm1633.9310.737.4830.32 40-50cm3445.128.8920.2329.99 50-60cm2353.2626.7918.8329.72 60-70cm1564.121.6714.7931.75 Rushes had approx 30% moisture content when harvested Slide 16 Moisture content Also looked at some commercial products MACE wood briquettes approx 25% NCF wood logs approx 15% Turf 16 - 35% Peat briquettes 10% Kiln dried wood 9% Miscanthus 9 - 20% Strogs 12% Slide 17 Energy content Used bomb calorimeter Calibrated with standard material Determines energy content by ability to heat known mass of distilled water when substance is combusted in presence of oxygen Slide 18 Slide 19 Energy Content Fuel MJ/Kg Coal 27.1 - 33 Straw Briquettes 16 Miscanthus 18 Turf14-18 briquettes17 >60cm rush17 50-60cm rush18.7 NCF wood logs19 Mace wood briquettes19 Slide 20 Summary to date High moisture content but relatively easy to dry Obviously dont have to get moisture to zero Very low ash content on combustion Very low density when dry Energy content comparable to currently available products Perhaps consider them as an addition Slide 21 Main source Forest Ecosystem Research Group Report Number 69