Biofuel potential of Rushes

1. Biofuel potential of Rushes

2. Scope • Potential of rush as a biofuel • Determine calorific value • Compare with available alternatives

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

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

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

6. Biology • Hab prefs previously covered • Rhizome permits vegetative growth producing new shoots and also reproduces by flowering www.irishwildflowers.ie

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

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

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

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

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

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 4–6 times per year was required to control the rushes but would not eliminate them.

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

14. Energy Content • Determined moisture content • 5 size classes of rush 20 – 30 cm 30 – 40 cm 40 – 50 cm 50 – 60 cm >60cm

15. Moisture content Rushes had approx 30% moisture content when harvested

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%

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

19. Energy Content

20. High moisture content but relatively easy to dry Obviously don’t 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 Summary to date

21. Main source • Forest Ecosystem Research Group Report Number 69