Short rotation coppice

Species used

SRC uses said high yield varieties of poplar and willow . Typically willow species chosen are varieties of the Common Willow Willow Oyster , Salix viminalis . Poplar is generally planted for visual variation rather than being a commercial crop, although some varieties can be outperformed. ^[2]

Species are selected for their acceptance of different climatic conditions and conditions, relative insusceptibility to pests and diseases, ease of propagation and speed of vegetative growth. To fight pests Such As brassy and blue willow beetles , as well as the fungal pathogen Melampsora (a rust ), planting was Carefully selected mix of varieties is recommended. ^[3] The management of plantations highly affected by productivity and its success. ^[4]

Planting

CBC can be planted on a wide range of soil types from heavy clay to sand, ^[5] including land reclaimed from gravel extraction and collar spoil. Where used as a pioneer species the SRC yield may be smaller. Water availability to the roots is a key determinant for the success of the SRC. ^[6] [7]

Saplings are planted at a high density, as much as 15,000 per hectare for willow and 12,000 per hectare for poplar. ^[3] Planting takes place in the early spring and early summer. The most efficient planting machines plant four rows at a time and can plant hectare in around three hours. Saplings are left to grow for one or two years and then coppiced .

The primary barrier to establishing plantations is a financial reward for a large initial investment. However, in the UK, they were available to support establishment, ^[8] [9] and in Sweden an extensive scheme of subsidies was developed during 1991-1996, being reduced after that time. ^[10]

Harvesting

Harvests take place on a two-to-five-year cycle, and are carried out in the fall. The root system and the nutrients stored in the roots and stumps guarantee vigorous growth for the shoots. A plantation will yield from 8 to 18 tons of dry woodchip per hectare per year. A plantation can be harvested for up to 20 years before needing replanted. ^[11]

When willow or poplar shoots are harvested as they are easy to store. The stems can be dried for burning in a pile outdoors; the moisture content of the wood will decrease 30% on average until the next autumn. The stems can be cut into other things that can not be used differently.

Where wood chip is being produced it is most efficient to use direct-chip harvesters. These are heavy self-powered machines that cut and chip the shoots on a loading platform. ^[12] Some can be attached to a normal tractor and can be harvested in around 3 hours. Direct chipping will be needed; however, the wood chip needs to be saved to avoid it composting. Harvesting Poplar requires heavier machinery as it produces fewer and heavier stems.

The price of dry fuel is currently around 45 euro per ton in most of Europe. This is a relatively high-return crop, but it is low-maintenance and is a way of using difficult fields. Small-scale production can be combined with the production of material for wicker work. Correctly managed, there is little need for pesticides or treatments.

Environmental impacts

Greenhouse gases

SRC has a low greenhouse gas impact as any carbon dioxide released in power generation will have been sequestered by the plantation over just a few years. Some carbon may also be stored in the soil, however the extent of this carbon storage is dependent on the carbon content of the soil to begin with. ^[13]

The carbon costs associated with SRC are: the planting, farming and chipping of the SRC planting, generally done with fossil fuel powered machinery; Fertilizers require herbicides during establishment, fertilize throughout growth, and occasional pesticide treatment. In general, the environmental contribution of the rotation of plantations may also be considered positive ^[14] even when alternative energy uses are considered. ^[15]

Furthermore, willow and poplar SRC offer an alternative to intense drained farmland. If the drainage of these sides would be reduced, this would have a positive impact on the CO ₂ -balance. In addition, it is possible to avoid negative effects on the local water-balance and more sensitive ecosystems. ^[16] [17]

Electricity or heat from SRC provides between three and six times the CO ₂ reduction per pound that can be obtained from bioethanol from cereal crops. HOWEVER, the reduction in CO ₂ emission is Slightly lower than grass energy crops Such As Miscanthus grass due to Higher service costs.

Biodiversity

Good conservation management encouraging biodiversity can reduce the reliance on pesticides. Biomass crops such as SRC willow show higher levels of biodiversity in comparison with intensive arable and grassland crops. ^[18]SRC has a higher water consumption than agricultural crops. The root systems of SRC have a lower impact on the archeology of agriculture.

Energy and Biofuel generation

A power station requires around 100 hectares (1 km²) of SRC for 1 MW of power capacity. ^[19] The current nature of the power supply is incompatible with the long term commitment SRC requires; however, there is much interest in SRC due to the need to reduce fossil carbon emissions. Grants may also be available in some jurisdictions to further this type of land-use.

Enköping (Sweden) is a successful model that combines heat generation from biomass, SRC and phytoremediation. The municipality is about 80 ha of plantations that are used in the district heating plant. At the same time, these plantations are used as a green filter for water treatment, which improves the functionality and efficiency of the whole system. ^[20]

Biofuel is another option for using SRC as bioenergy supply. In the United States, scientists studied converting SRC poplar into sugars for biofuel (eg ethanol) production. ^[21] Considering the possible process, the process of making biofuel from SRC can be economically feasible, but the conversion yield from SRC (as juvenile crops) has been lower than regular mature wood. Besides biochemical conversion, thermochemical conversion (eg fast pyrolysis) was also studied for making biofuel from SRC poplar and was found to be more energy efficient than that of bioconversion. ^[22]

See also

• Biomass
• Bioenergy
• Energy forestry
• Miscanthus
• Non food crops
• Poplar
• Short rotation forestry
• switchgrass
• Willow
• Wood fuel

References