Fuel considerations for biomass boilers are paramount and require careful consideration before a particular type of boiler is selected. Today we will look at some of the most important considerations.
The fuel type, and delivery, storage and handling arrangements can have a dramatic impact on through life costs. Getting it right for an individual project is a key function of the initial concept stage of a biomass installation.
At the end of the day, optimum and efficient boiler performance will only be achieved if the right quality of fuel is used. Poor quality fuel can lead to poor combustion and loss of efficiency, auger blockages and flue problems with tar and fly ash.
Many of these problems can be avoided by selecting a fuel supplier that is a member of a fuel supply accreditation/assurance scheme, such as that undertaken by Woodsure/HETAS. Accredited fuel suppliers are listed on the Biomass Supplier's List (BSL).
Fuel type, storage, and delivery arrangements should be considered in parallel with the choice of boiler. This is a clear and proven recipe for success but can unfortunately not always be adhered to. It isn’t a case of choosing the boiler and then the fuel, it is more of an interactive process and is very site-specific.
Whilst this may seem daunting, in reality it isn’t. Space and available storage are a main consideration. Where space is limited the choice may be wood pellets and access for delivery vehicles, their turning circle and size of delivery load comes into play. Ideally the fuel store should be sized to take a full load and give the site a sufficient volume in reserve to avoid running out as well as driving scale economies.
Commissioning day is of course a landmark day for any installation. After pre-checking the operation of the fuel handling and delivery system, the fuel store needs to be filled with at least sufficient fuel for commissioning –between one and two cubic netres is usually sufficient. Sometimes this may have to be bagged if a full delivery can’t be timed for the day. This is where early liaison with the fuel supplier is essential. particularly as it is the first delivery. Any delays in delivery can also lead to a costly delay in commissioning – or indeed commissioning not taking place at all.
Once the site is commissioned, you will need to plan ahead. Monitoring wood fuel usage in the early days is vital to build up an accurate picture in order to assist with forecasting your fuel use. Be sure to remember that if your boiler is commissioned during the summer, that you will need far more fuel during the colder winter months.
Liaise in good time with your preferred supplier regarding refilling or obtain quotes if you’re not linked into any kind of long term supply contract. We suggest allowing a good two weeks from placing your order to receiving the fuel and you will need to make sure you have sufficient fuel to last during that time.
Whilst the wood fuel industry is expanding rapidly, and there are a lot of willing and eager suppliers keen to support customers, there are practical limitations to wood fuel and supply. Wood chip in particular has to be produced from seasoned timber and this takes at least a year, including a full summer.
It’s important to prepare for the winter heating season in advance, especially if your boiler is switched off for the summer. Plan your annual boiler service well in advance, and have the fuel ready on site for re-commissioning the boiler as part of servicing. A regularly serviced boiler will perform at its most efficient and cost effective.
As well as maintaining your boiler, it’s important to maintain your store too. Periodically, when empty, arrange for it to be cleaned out of dust and arisings. However, be aware this should be undertaken as part of servicing and not by unqualified individuals. There can be the presence of Carbon Monoxide and there are hazards with rotating machinery in the stores. A safe process of work needs to be adhered to and the work should be undertaken by those trained and competent to do so.
For the foreseeable future, small and medium scale biomass (below 1MW) will not have to provide evidence of sustainability criteria for fuel supplies. However it will be good practice to keep all delivery notes and receipts, which detail the supplier and moisture content and standard of fuel delivered. This provides a good traceability of the delivered fuel. An accredited/assured supplier will have full sustainability details.
Wood fuel supply is not onerous, but there are basic steps and procedures that need to be followed. If they are, these steps will ensure years of trouble-free operation and good performance from the boiler. Best practice is to consider fuel type and supply options at the very outset of the project. It is important to make the fuel store as large as practically possible and ensure your supplier understands the site and the delivery route. With these practical, basic steps complete, and ensuring you take fuel from an accredited and assured supplier your fuel supply should be trouble-free.