Miscanthus

 

Key Words - Bioenergy, energy crops, Miscanthus

 

Description

Miscanthus is a perennial, rhizomatous grass, originating from Asia, which possesses the C4 photosynthetic pathway. The most common species is Miscanthus giganteus which is a sterile triploid hybrid of M. sacchariflorus and M. sinensis.

Planting

Site preparation is essential for good establishment. Rhizomes are planted in the spring at 20-30,000 per hectare using semi-automatic potato planters or bespoke planters. It is vital that sites should be cleared of perennial weeds before any planting takes place. It is particularly important that the rhizomes are planted in a fresh condition, are kept moist and below 4oC from lifting until re-planting.
Miscanthus plantations need 3-5 years to become fully established and to obtain maximum yield level.

Growing Cycle
  • Planting rhizomes in springtime: first harvest in years 3-5 (low yields in the first two years)
  • Shoots emerge annually from the soil during March
  • Crop reaches maximum height in the summer (robust stems)
  • Crop drying in Autumn, nutrients move back into rhizome
  • Leaves fall off and stems dry during winter (30-50% mc)
  • Canes without leaves remain ready to be harvested mechanically in spring; moisture content has dropped significantly to ~20%
Harvesting

Canes with a height of up to 3-4 metres are harvested in early spring, generally between March and April, every year for about 15-20 years before new planting is required. Harvesting can be carried out using conventional farm machinery, producing either bales or chipped material. The soil must be suitable for heavy machinery.

Yield

Based on the results of yield trials in England and Northern Ireland and on experience in the Republic of Ireland, the dry matter yields from Miscanthus can be expected to be similar to those for the North of England and in the range of 12-15 tonnes dry matter per hectare per year.
Key determinants of yield are planting density, soil type, sunshine, temperature and rainfall (recommended >550 mm). Highest yields are produced on soils with a good water holding capacity. Miscanthus has a very low nutrient requirement due to the return of plant nutrients through leaf litter decomposition.

Storage

Correct storage of Miscanthus is dependant on the moisture content of the bales, which is recommended to be ≤15oC to prevent occurrence of mould. Miscanthus has a low bulk density which should be considered for transport and storage.

Pests/disease

To date no reported insects or other pests in Europe have significantly affected Miscanthus.

Markets

An end use for Miscanthus should be lined up before planting.
Miscanthus can be used as a fuel in special Miscanthus boilers which are especially made to handle and burn it efficiently. It can also be burnt in Biomass-CHP units and for co-firing in power stations. The boiler manufacturer's warranty should cover Miscanthus as a fuel.

Table of Properties
PropertyDescription
Moisture content at harvest20-50%
Bulk density (baled)130-150 kg/m3
Bulk density at harvest (chopped)70-100 kg/m3
Calorific value (Net)

~17 GJ/tonne (dry basis)

~3.8 kWh/kg (20% moisture content)

Ash contentTypically 2-3%
Ash fusion (melting)temperature1090oC

Temperature at which some sintering observed		600oC


Grants

Planting energy crops, Department of Agriculture Fisheries and Food:
The objective of the scheme is to provide establishment grants to farmers to grow willow and miscanthus to produce biomass suitable for use as a renewable source of energy. For more information please visit:
http://www.agriculture.gov.ie/ruralenvironment/climatechangebioenergybiodiversity/bioenergy/bioenergyscheme/

Miscanthus Boiler installations, SEAI:
The Miscanthus Pilot Demonstration Programme, funded under the Renewable Energy RD&D Programme, provides assistance for the deployment of renewable heating systems fuelled by Miscanthus in industrial, commercial, public and community premises in Ireland. The programme is administered by the Sustainable Energy Authority of Ireland (SEAI). For more information please visit:
http://www.seai.ie/Grants/Renewable_Energy_RD_D/Miscanthus_pilot/

Abbreviations
%percentmcMoisture content
>GreaterGJGigajoule
<LessmmMillimetres
kgKilogramoCDegree Celsius
m3Cubic metres  

 

References, downloads and recommended Literature Miscanthus:

 

Contact:

Tom Knitter
Sustainable Energy Authority of Ireland
Renewable Energy Information Office
Unit A, West Cork Technology Park
Clonakilty
Co. Cork
Tel: 023 8842193
Email: tom.knitter@reio.ie

 

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