biomass

Correctly managed, biomass is a sustainable fuel that can offer a wide range of benefits:

Biomass is a “carbon lean” fuel producing a fraction of the Carbon emissions of fossil fuels.

Biomass can be sourced locally, from within the UK, on an indefinite basis, contributing to security of supply.

UK sourced biomass can offer local business opportunities and support the rural economy.

The establishment of local networks of production and usage, allows financial and environmental costs of transport to be minimized. There is no region in the UK that cannot be a producer of biomass.

The use of biomass fuel provides an economic incentive to manage woodland which improves biodiversity.

Many biomass fuels generate lower levels of such atmospheric pollutants as sulphur dioxide, that contributes to ‘acid rain’. Modern biomass combustion systems are highly sophisticated, offering combustion efficiency and emission levels comparable with the best fossil fuel boilers.

Biomass residues, arisings, co-products and waste not used for energy, or some other application will usually rot. This will generate CO2 in any case, and may also produce methane (CH4), a greenhouse gas 21 times more potent that CO2.

Biomass Energy Facts

  • Biomass is all plant and animal matter – anything that was alive
  • Biomass generally refers to low value wood from logging
  • Tree tops, branches and other scraps are ground to wood chips
  • The wood chips are burned by energy plants to make electricity
  • Biomass fuel is renewable.  We can grow more in a short time
  • Biomass is not a “fossil” fuel, like oil, gas, or coal
  • Biomass gets it’s energy from the sun, through photosynthesis
  • Biomass plants are cleaner-burning than fossil fuel plants
  • Energy from biomass produces almost no mercury or sulphur

Chemical composition

Biomass is carbon based and is composed of a mixture of organic molecules containing hydrogen, usually including atoms of oxygen, often nitrogen and also small quantities of other atoms, including alkali, alkaline earth and heavy metals.  These metals are often found in functional molecules such as the porphyrins which include chlorophyll which contains magnesium.

Plant material

The carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun.

Plants may subsequently be eaten by animals and thus converted into animal biomass. However the primary absorption is performed by plants.

If plant material is not eaten it is generally either broken down by micro-organisms or burned:

If broken down it releases the carbon back to the atmosphere, mainly as either carbon dioxide (CO2) or methane (CH4), depending upon the conditions and processes involved.

If burned the carbon is returned to the atmosphere as CO2.

These processes have happened for as long as there have been plants on Earth and is part of what is known as the carbon cycle.

Fossil fuels

Fossil fuels such as coal, oil and gas are also derived from biological material, however material that absorbed CO2 from the atmosphere many millions of years ago.

As fuels they offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and the hydrogen to water (vapour).  Unless they are captured and stored, these combustion products are usually released to the atmosphere, returning carbon sequestered millions of years ago and thus contributing to increased atmospheric concentrations.

The difference between biomass and fossil fuels

The vital difference between biomass and fossil fuels is one of time scale.

Biomass takes carbon out of the atmosphere while it is growing, and returns it as it is burned.  If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. This is either during woodland or arboricultural management or coppicing or as part of a continuous programme of replanting with the new growth taking up CO2 from the atmosphere at the same time as it is released by combustion of the previous harvest.

This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels.

Categories of biomass materials

Within this definition, biomass for energy can include a wide range of materials.

The realities of the economics mean that high value material for which there is an alternative market, such as good quality, large timber, are very unlikely to become available for energy applications.  However there are huge resources of residues, co-products and waste that exist in the UK which could potentially become available, in quantity, at relatively low cost, or even negative cost where there is currently a requirement to pay for disposal.

There are five basic categories of material:

  1. Virgin wood, from forestry, arboricultural activities or from wood processing
  2. Energy crops: high yield crops grown specifically for energy application
  3. Agricultural residues: residues from agriculture harvesting or processing
  4. Food waste, from food and drink manufacture, preparation and processing, and post-consumer waste
  5. Industrial waste and co-products from manufacturing and industrial processes

Biomass

Fuel

A type of wood fuel made from compacted sawdust, wood pellets are cylindrical in shape, usually measure between 6-10mm in diameter and are 10-30mm long. They are usually produced as a by-product of saw-milling. Wood pellets are much denser than natural wood with a low moisture content of less than 10% that allows them to be burned with very high combustion efficiencies.

Cost: Approx £200 – £230 per 960kg (10kg Bags)

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