to read the full report - Ecolateral by Peter Jones

Evaluation of Opportunities for Converting Indigenous UK Wastes to Wastes and Energy
AEA/ED45551/Issue 1
7 Solid recovered fuels and other fuels
manufactured from waste
Each energy conversion technology is limited in the range of fuel types that it can accept and places
demands on the preceding steps in the chain, in terms of fuel quality, properties and composition.
Technologies are being introduced in the UK and elsewhere that transform waste components from their
raw form to standard fuels with a defined specification. Manufactured fuels can offer the following
benefits:
• Consistent properties that can be defined and used in contracts making the material a tradable
commodity.
• Physical and biological stability that makes longer term storage possible and can even out
unbalances between the constant supply of waste and the seasonal demand for energy.
• An opportunity to manage the properties of the fuel to achieve optimum performance from the
energy technology.
These fuels are in many ways the key to using waste in a diverse range of energy technologies that offer
higher resource use efficiency and enhanced greenhouse gas reduction potential when compared to
traditional combustion with energy recovery. They allow CHP installations to be sized according to the
heat load and processes to manufacture transport fuels and methane to be operated at an economic
scale.
We have identified the following manufactured fuels on sale or planned in the UK.
• Solid recovered fuels. These fuels are produced from mixed wastes from the municipal and
commercial stream by separating the high heating value components from the residues remaining
after conventional recycled products have been removed. The material contains both biological
and non-biological matter. They are supplied dried and either shredded for short distance and
short term transport or compressed into pellets for longer distances and storage times.
• Graded waste wood fuels. This sector is growing rapidly as wood fired power plants are built to
take advantage of the reformed Renewables Obligation. Waste wood is collected from industry
and amenity centres and graded depending on the level of contamination. The grades are then
chipped and sold to a specification.
• Clean grade wood chips from virgin materials. Here wood residues for forestry and sawmills
are chipped and potentially dried to meet a specification.
• Domestic grade wood pellet fuel from saw mill by-product. Sawmill residues, in particular
sawdust, is dried and compressed through a die into small cylinders approximately 6mm in
diameter and 10 mm long. This fuel resembles cattle feed or cat litter and is clean and free
flowing. Several small scale combustion appliances have been developed to take advantage of
the properties of this fuel. The high energy density means that it can be transported economically
regionally, nationally, and internationally.
• Industrial grade pellet from forestry, cereal processing residue and clean waste wood.
This is similar to the domestic pellet but has a higher ash content and larger size.
• Thermochemical fuels. These are chars and pyrolysis oils produced close to the point of
arising. Supplied either separately or as a slurry mix, the increased energy density extends the
economic transport distance for local to national. These fuels are not currently produced but
have been proposed as a feedstock option for large gasification processes producing 2 nd
generation biofuels or Substitute Natural Gas (SNG). We also include torrefaction, or high
temperature drying in this category.
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