Short Rotation Willow

 

Bacenetti ^[18] and Barontini ^[19] both lead studies into the use of short rotation willow as a source of biomass. This study was based in Italy where there is approximately 120,000 hectares of SRC, in contrast to 2,800 hectares in the UK in 2008. The low uptake in the UK was highlighted as being due to a lack of knowledge and the 3-4 year wait before the first crop ^[20]. They found that that 2-5 year cutting times are the most popular and that the longer a farmer is able to leave the crop before harvest, the better the economic performance, up until 5 years.

Stephenson et al ^[21] noted that willow is suitable for cultivation on low quality land and as an added benefit, it does not require ploughing.

 

The Moray Council ^[22] again reiterate the versatility of willow. They found it can thrive in a wide range of soils, even remedying polluted soils, and can attract a high biodiversity of wildlife. However it was noted that willow does not grow well in urban areas with high concentrations of air pollution.

 

Existing Supply Chains

 

Some small scale examples from the British Isles include ^[23]:

 

Gurteen College (ROI): 32 hectares planted in arable land to supply two 300kW boilers used for heating.

Strawson's Energy (England): 400 hectares planted to supply Drax power station.

Hegan Biomass (Northern Ireland): production capacity of 20,000 tonnes/year, used locally as a heat supply.

 

From these examples and from the literature review carried out, it is clear that while willow appears to be a feasible crop for use as fuel, there seems to be little evidence of any large scale supply chains.

 

Barriers to Large Scale Uptake

 

Using the DECC BEAC tool it is clear that growing willow on farmland is the best way to ensure that life cycle CO₂ emissions are kept as low as possible.

 

To do this, farmers would need to be relied upon to grow the crop. However farmers are often driven by financial incentives so growing willow would need to be more attractive than more conventional food crops. Unfortunately this is not the case as historically wheat prices have been higher than woodchip prices. Depending on the moisture content, the price of woodchips per tonne varies from around £90-150. Wheat prices are more volatile and have dropped in recent years,  as shown in the graph below ^[24].

Regardless of the price, the wait for the first crop, 1-3 years is off putting to farmers, as is the lack of machinery.

 

There have been incentives such as the Energy Crop Scheme which tried to increase the growth of energy crops by farmers,  they have had very little effect.