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Biofuel potential of Rushes

Date post: 05-Jan-2016
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Biofuel potential of Rushes. Scope. Potential of rush as a biofuel Determine calorific value Compare with available alternatives. Juncus effusus. Juncus family - Approx. 300 spp worldwide J effusus habitats are diverse moist areas at forest margins, wet grasslands, - PowerPoint PPT Presentation
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Biofuel potential of Rushes
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Page 1: Biofuel potential of Rushes

Biofuel potential of Rushes

Page 2: Biofuel potential of Rushes

Scope

• Potential of rush as a biofuel

• Determine calorific value

• Compare with available alternatives

Page 3: Biofuel potential of Rushes

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

Page 4: Biofuel potential of Rushes

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

Page 5: Biofuel potential of Rushes

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

Page 6: Biofuel potential of Rushes

Biology

• Hab prefs previously covered

• Rhizome permits vegetative growth producing new shoots and also reproduces by flowering

www.irishwildflowers.ie

Page 7: Biofuel potential of Rushes

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

Page 8: Biofuel potential of Rushes

Growth

Growth reaches a maximum in the summer and is generally positivelycorrelated with seasonal climatic factors, and negatively correlated with standing - dead biomass parameters

Page 9: Biofuel potential of Rushes

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

Page 10: Biofuel potential of Rushes

‘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

Page 11: Biofuel potential of Rushes

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

Page 12: Biofuel potential of Rushes

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.

Page 13: Biofuel potential of Rushes

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

Page 14: Biofuel potential of Rushes

Energy Content

• Determined moisture content– 5 size classes of rush

20 – 30 cm 30 – 40 cm 40 – 50 cm 50 – 60 cm >60cm

Page 15: Biofuel potential of Rushes

Moisture content

Length class Number of rushes Mean length Wet mass(g) Dry Mass % Moisture

20-30cm 12 25.46 4.35 3.01 30.72

30-40cm 16 33.93 10.73 7.48 30.32

40-50cm 34 45.1 28.89 20.23 29.99

50-60cm 23 53.26 26.79 18.83 29.72

60-70cm 15 64.1 21.67 14.79 31.75

Rushes had approx 30% moisture content when harvested

Page 16: Biofuel potential of Rushes

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%

Page 17: Biofuel potential of Rushes

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

Page 18: Biofuel potential of Rushes
Page 19: Biofuel potential of Rushes

Energy ContentFuel MJ/Kg

Coal 27.1 - 33

Straw Briquettes 16

Miscanthus 18

Turf 14-18

briquettes 17

>60cm rush 17

50-60cm rush 18.7

NCF wood logs 19

Mace wood briquettes 19

Page 20: Biofuel potential of Rushes

Summary to date

• 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

Page 21: Biofuel potential of Rushes

Main source

• Forest Ecosystem Research Group Report Number 69


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