Biomasa

Oilseed Rape straw as a biomass fuel source
Harper Adams University College

Project Report
SUMMARY
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Image courtesy of T. Pickthall

Oilseed Rape (OSR) straw shows considerable promise as a crop residue biomass fuel. Being an agricultural waste product, it offers a significant environmental benefit in the food versus fuel debate that has arisen from the increasing use of energy cropssuch as Miscanthus. It also offers the opportunity to increase the gross margin of the OSR crop. Straw is a difficult material to handle and transport because it typically has a low density. By processing straw into pellet form, its bulk density can be more than doubled, offering a significant logistical benefit. There is however a production cost and energy usage associated with pelletising straw.A project sponsored by the Douglas Bomford Trust and the Claas Foundation is underway at Harper Adams to determine whether OSR straw pellets present a suitable and economically viable alternative to traditional fuels.

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THE NEED FOR ALTERNATIVES TO FOSSIL FUELS
Fossil fuels are the dominant source of global energy, accounting for approximately 80% of world energy consumption and 90%of UK energy demand in 2006. Fossil fuel use is also the principal source of UK carbon dioxide emissions, accounting for some 586 million metric tons of carbon dioxide emissions in 2006 (EIA, 2008). Renewable energy sources have long been identified as desirable alternatives to fossil fuels, providing a sustainable, low carbon dioxide source of power and heat which also improves the security anddiversity of energy supply. The EU target is for 20% of all energy consumption to come from renewable sources by 2020. The UK’s contribution to this challenging and highly optimistic target is to increase the energy we obtain from renewable sources from 1.5% in 2006 to 15% by 2020. The main renewable energy technologies are wind, hydroelectric and tidal for the generation of electricity and biomassfor both electricity and heating.

Author Leticia Chico-Santamarta
Postgraduate Researcher Harper Adams University College

Other 1.8 % Wind 8.8% Hydro 7.6%

Biomass 81.8%

BIOMASS
There are two main sources of biomass for energy generation; purposegrown ‘energy crops’ and residual materials from food crops. Energy crops, such as Miscanthus and Short Rotation Coppice, are cultivatedmainly for energy purposes, but have the well-known disadvantage of using land that may better be utilised for food production. The use of agricultural residues such as straw for energy generation avoids some of the food vs. fuel dilemma and may also add value to existing food crops. As part of its commitment to EU targets, the UK target is for 30% of all renewable electricity and heat (4.5% of totalenergy) to be obtained from biomass by 2020. In the UK in 2007, biomass accounted for 81.8% of all renewable energy generated, but this was only 2.3% of total UK electricity generation and less than 1% of heat needs. Biomass use therefore needs to increase by more than double by 2020 to reach the EU target.

Figure 1. Split of UK renewable energy types (2007). In total they represented 6.28% ofprimary energy used, equivalent to 5.17M tonnes of oil.

OILSEED RAPE STRAW AS A BIOMASS CROP
One agricultural residue that could be used as a fuel for energy generation is Oilseed Rape Straw (OSR, canola, Brassica napus). In the UK, the total area of OSR harvested increased from 332,000 to 598,000 ha between 2000 →

Image courtesy of M. Robinson

Harper Adams University College, Newport,Shropshire, TF10 8NB Telephone: +44 (0)1952 820280 Fax: +44 (0)1952 814783 Website: www.harper-adams.ac.uk

Oilseed Rape straw as a biomass source
and 2008, representing 12.6% of the total crop area (DEFRA, 2009). Currently there is not a significant market for OSR straw in the UK, and a large proportion of it is chopped and incorporated into the soil through ploughing. Consequently,...