ABOUT BIOMASS ENERGY
Biomass is all plant and animal matter on the Earth's surface. Biomass is anything that is alive. It is also anything that was alive a short time ago. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived 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. 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.
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.
Categories of biomass materials
Within this definition, biomass for energy can include a wide range of materials.
There are five basic categories of material:
- Virgin wood, from forestry, arboricultural activities or from wood processing
- Energy crops: high yield crops grown specifically for energy applications
- Agricultural residues: residues from agriculture harvesting or processing
- Food waste, from food and drink manufacture, preparation and processing, and post-consumer waste
- Industrial waste and co-products from manufacturing and industrial processes.
Why use BIOMASS?
Biomass is a renewable, low carbon fuel that is already widely, and often economically available throughout the UK. Its production and use also brings additional environmental and social benefits. Correctly managed, biomass is a sustainable fuel that can deliver a significant reduction in net carbon emissions when compared with fossil fuels.
The problem with burning fossil fuels
Burning any carbon-based fuel converts carbon to carbon dioxide. Unless it is captured and stored, this carbon dioxide is usually released to the atmosphere. Burning fossil fuels releases carbon that was removed from the atmosphere millions of years ago by animal and plant life. This leads to increased concentrations of carbon dioxide in the atmosphere.
What is the Greenhouse Effect?
The greenhouse effect is the heating of the surface of earth due to the presence of an atmosphere containing gases that absorb and emit infrared radiation.
Greenhouse gases, which include carbon dioxide, water vapor and methane, are almost transparent to solar radiation but strongly absorb and emit infrared radiation. Thus, greenhouse gases trap heat within the surface-troposphere system
The increasing concentrations of greenhouse gases in the atmosphere since the industrial revolution and the resulting widespread use of fossil fuels, gives rise to an increase in the greenhouse effect, and an increase in the average global temperature, known as Global Warming. This is predicted to lead to widespread, unpredictable changes to the global climate.
Using biomass to achieve a carbon balance
The combustion (direct or indirect) of biomass as a fuel also returns CO2 to the atmosphere. However this carbon is part of the current carbon cycle: it was absorbed during the growth of the plant over the previous few months or years and, provided the land continues to support growing plant material, a sustainable balance is maintained between carbon emitted and absorbed.
- As trees in the energy plantation grow, they absorb carbon dioxide from the atmosphere.
- During photosynthesis the trees store carbon in their woody tissue and oxygen is released back to the atmosphere.
- At harvest, wood fuel is transported from the plantation to the heat or power generating plant.
- As the wood is burned at the heat or power generating plant the carbon stored in the woody tissue combines with oxygen to produce carbon dioxide, this is emitted back to the atmosphere in the exhaust gases.
The amount of additional biomass that grows over the course of a year in a given area is known as the annual increment. Provided the amount consumed is less than the annual increment its use can be sustainable and biomass can be considered a low carbon fuel and biomass CO2 absorption and emission is in balance.
5 Good reasons to use biomass as a sustainable fuel:
- Correctly managed, biomass is a sustainable fuel that can both offer a significant reduction in net carbon emissions compared with 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, although some have greater productivities than others.
- Woodlands, forestry and agriculture are generally perceived to be an environmentally and socially attractive amenity by the UK population, providing opportunities for recreation and leisure activities.
Source: The Biomass Energy Centre UK: www.biomassenergycentre.org.uk