The majority of woodfuel systems have a very specific range of fuel requirements if they are to operate reliably, efficiently, with low levels of emissions and without blockage of the fuel feed system.
Matching supplies to fuel requirements is critical
There is a fairly widespread belief that any batch of wood makes acceptable woodfuel. There are some generally relatively large scale systems that can accept a wide range of woody material as fuel. However the majority of biomass systems have a very specific range of requirements and are designed to shut down automatically if the fuel leads to operating parameters outside a predetermined acceptable range.
The majority of problems with biomass installations in the UK are associated with the fuel. With biomass a relatively novel fuel in the UK, every difficulty can be perceived as a failure of the biomass concept and can attract disproportionate negative publicity. This can damage the biomass market and hinder the development of the biomass industry.
Mismatches between fuel requirements and fuel supplies can arise for a number of reasons:
- The system installer not ensuring a local fuel supply, or not fully informing the user of what is required
- The user not understanding the importance of correct fuel specifications, or attempting to economize
- The fuel supplier not understanding the importance of correct fuel specifications, the fuel specifications required, or mis-selling or misrepresenting the fuel.
It is therefore the responsibility of all links in the chain to ensure they, and those they are dealing with, know the specification required for a given system. This is the reason for a suite of internationally agreed solid biofuel standards covering many different forms of woodfuel and biomass.
For those receiving payments under the RHI, there is a database of approved suppliers of biomass (Biomass Suppliers List, BSL)who have demonstrated the sustainability of their fuel. It is obligatory to use a supplier from this list if you are receiving support under the domestic RHI, unless you are a self supplier.
Supplying different kinds of fuels
Specifications for solid biofuels are set out in the upcoming European Standard, EN335, and cover many fuels and many parameters including ash content, calorific value, contents of various elements, and technical standards for determining these parameters are also published.
Further information:
Fuel supply models
Self-supply
The owner of the combustion or energy system supplies their own fuel from their own estate. They are then responsible for ensuring adequate supply of fuel to the appropriate standard. It is therefore particularly important to ensure that the equipment installed is appropriate to use the fuel available, and that there will be sufficient fuel available. If necessary it might be possible to supplement with fuel from another local supplier.
Co-operative
A number of producers of biomass collaborate on the supply of fuel. This can be an efficient model that allows specialized equipment such as a chipper or delivery lorry to be shared between members of the co-operative, and collaboration on marketing and administration. It can also help to ensure that there is always fuel available to meet demand even if a particular member may be unable to supply at a particular time.
Fuel merchant
The fuel supplier produces and/or buys fuel for sale to customers. They may offer different grades or specifications of fuel for different customers or applications.
The fuel broker sources fuel from a number of suppliers for purchase by customers. They may identify different grades or specifications of fuel for different customers or equipment, allowing optimum use of biomass available.
Energy Service Company (ESCO)
An ESCO is contracted to supply heat rather than fuel. They may also own the combustion equipment, may be contracted to maintain it, or may lease it from another company, but are paid on the basis of heat delivered. This is metered on the basis of water flow rate and temperature differential between inflow and outflow, rather than fuel supplied. This is a popular model in Europe, particularly for district, site and building heating systems.
