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BIOMASS BOILERS Releasing the stored energy of wood to generate heat

We could help you save up to 50% off your heating bill. Read on...

What Are The Benefits? q Reduce Your Energy Bills By Up to 50%

On a unit cost-basis, biomass fuels can be cheaper than many fossil fuels commonly used for heating. When replacing fuel sources that are used in locations that do not have access to mains gas, such as electric, LPG or heating oil, a pellet-wood boiler may cut your heating bill by up to 50%. The payback on capital can therefore be very rapid, in some cases less than 3 years. Savings will depend on how much they are used and which fuel you are replacing. This level of saving will not be achieved if replacing mains gas, but Green Energy Doctor can help you calculate the level of benefit.

q Reduce Your Carbon Footprint

Pellets contain stored solar energy. When burning wood, CO2 is released along with a few other by-products of combustion. However, this is largely offset by what was absorbed (via photosynthesis) during the growth of the tree. Heating with wood pellets is thus CO2 neutral. Furthermore, if the wood were to rot, it would release the same amount of CO2 as if it were burnt.

q Easy To Use As A Fossil Fuel System

Modern pellet-wood boilers are compact units that offer similar levels of convenience to oil and gas boilers. They have remote control and outdoor temperature regulation; you simply set the desired heating times and let the advanced technology work for you. They have self-cleaning and integrated ash compaction systems that mean you only need to empty the ashtray every 6 to 8 weeks.

q Support Your Local Economy

Fuels used typically with biomass heating systems tend to have diverse and localised fuel supply chains. UK sourced biomass can offer local business opportunities and support the rural economy.

q Improved Efficiency

Unlike fossil fuel boilers that generally regulate by switching themselves on and off, pellet boilers modulate their firing rate to match the exact energy requirements in your property. This leads to a lower incidence of starting and stopping the system, a high level of efficiency and a long life of the appliance, all of which means a lower energy bill and operating cost for you.

q Improved Energy Performance Ratings For Buildings

Using biomass heating equipment in new or refurbished building stock could help to improve its overall environmental energy performance and help it to achieve lower carbon emissions as represented in an EPC (Energy Performance Certificate).

“With today’s soaring oil costs, biomass can be an excellent heating alternative that can reduce energy bills and the environmental impacts associated with fossil fuel use.”

What do we mean by Biomass? Biomass is material that is derived from biological products, such as wood and plants that can be used as a fuel to produce energy when burned. There are a number of different types of biomass fuels, however, the most popular types of biomass for domestic space heating and hot water purposes are logs, wood chips or wood pellets. Wood pellets are made from low-grade by-products of the wood processing industry such as dry sawdust and shavings, produced in large quantities. The material is compressed under high pressure and extruded through a mould to form pellets. The heat they produce when burning is comparable to domestic heating oil, however, they are approximately 40%* cheaper and require less storage space than lower density fuels such as wood chips.

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A typical biomass carbon cycle. 1. Atmospheric carbon dioxide, water and sunlight, 2. Converted into new plant material through photosynthesis, 3. Harvested and burnt, 4. Carbon released back into the atmosphere.

Why is biomass considered a renewable low carbon fuel? The primary source of energy contained within all biomass fuels is energy from the sun that is captured and stored via the process of photosynthesis. This energy can be released and used (e.g. by combustion). When this occurs, CO2 is released. However, the CO2 released is largely offset by that which was absorbed in the original growth, or which will be captured in the growth of new biomass to replace the biomass being used (as illustrated above). Consequently biomass combustion is considered to be a low carbon technology if the material is derived from sustainable sources.

A simple transition from fossil fuels For many people, biomass was once considered to be an inefficient fuel that required a manual process of carrying heavy baskets of dirty logs. However, in recent years, biomass has seen a complete transformation with improvements in biomass fuel, burning technology and automated systems that offer similar convenience to fossil fuel boilers.

“Biomass can be an excellent alternative as a primary heating fuel and can provide an excellent solution to reducing energy bills and your carbon footprint.� *Correct at time of going to print

How Does a Biomass Boiler Work? Green Energy Doctor will consider a number of systems including wood chip and log fed boilers in creating the solution for your needs. However, the type of system that Green Energy Doctor generally recommends for households and small commercial applications is a pellet-burning boiler. A pellet-boiler is similar in principle to a fossil fuel boiler in that they combust a fuel that produces heat, which is captured and transferred to be used for space heating and hot water production, using your existing central heating system. The primary differences being that they burn wood-pellets instead of a fossil fuel. They use microprocessors to control the amount of fuel and air being supplied, ensuring high efficiencies (often in the range of 90%-96%). Another difference is the feed system of these biomass boilers that are based on a suction system or a spiral conveyor (auger) moving the fuel from the hopper to the combustion chamber and making the process largely or fully automatic and featuring all the facilities available on modern fossil fuel boilers and more.






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Biomass boilers produce heat, which is captured and transferred to be used for space or water heating. 1. Pellet Hopper, 2. Spiral Conveyor, 3. Combustion Chamber, 4. Heat Exchanger, 5. Heat transferred to heating system and hot water cylinder, 6. Ashtray.

“If you don’t have access to mains gas, biomass boilers are a particularly cost effective solution with all the convenience of a traditional boiler.” How Much Does It Cost To Install? Prices of pellet-wood boilers are higher than those of gas boilers and oil boilers. They vary a lot and depend on elements such as brands, output, controls and specific features. But expect to pay 5 times more for a pellet-boiler than for a gas or oil version. However, it is always important to remember that any ongoing savings achieved by moving from your existing fuel to biomass, will offset the initial investment. Once the technical survey has been carried out and the property found suitable, Green Energy Doctor will provide you with a fixed price for completing the job.

Is It Suitable For My Requirements? Biomass can be an excellent alternative as a primary heating source and can provide an excellent solution to reducing energy bills, particularly if you are one of the 2.8 million properties in the UK that does not have access to mains gas. However, deciding whether a biomass system is appropriate for you or your project requires consideration of a number of factors. The following are some general principles that will help you decide whether it is a technology you would like to consider in more detail for your property or project, we will of course take all these and more into account when designing an efficient and smooth operating biomass system:

Fuel Supply & Quality

Size Of Boiler

Fuel Delivery

Heat Demand/Optimum Firing

Whenever a biomass installation is planned, the intended sources of fuel should always be included in the planning and the equipment specified accordingly. Green Energy Doctor can assist you in finding a suitable fuel supply. In the UK, pellets are available by the bag and in some areas by bulk tanker. For a boiler, a typical storage unit may require filling once or twice a year for pellets. This typically requires both vehicular access and a convenient way to transfer the fuel from the delivery lorry into the store.

Fuel Storage

Any design must ensure that there is a suitably dry area, sufficiently close to the intended site of the boiler. For a primary central heating system for a house, a fuel store approximately the size of a garden shed is recommended, preferably larger for wood chips. However, some models come with a small in-built storage system. Green Energy Doctor will properly design a suitable storage system if required.

Domestic and light industrial biomass boiler systems tend to be slightly larger than their fossil fuel equivalent. With high density modern housing, making space available for a fuel store can sometimes be a challenge. It is very important not to over specify biomass boilers and take seasonal variation into account. Where seasonal operation varies between high-level output for winter heating and low-level output for summer hot water, a biomass boiler supplemented by a solar thermal system might offer a suitable combination. Green Energy Doctor will be able to specify a suitable system size.

Heating System

A biomass boiler will connect to most existing wet radiator central heating systems that are typical in UK homes. Green Energy Doctor will be able to advise on the suitability of your current system and any potential small changes that might be required to make the system suitable.

Which system, equipment and features most suit your property or project, depends on a number of factors, but don’t worry, Green Energy Doctor technical expertise is on hand and will take all these into account as part of the design.

Please feel free to call us, send us an email or send us a drawing of your specific project.

How To Get Started‌ To find out more information on our services or to understand what technologies might be suitable for your needs, please visit our website and use our renewable energy decision tool, or give us a call to organise a no obligation home visit. Contact the Green Energy Doctor today on:

0845 009 5652

Energy & Resource Conservation Sustainable Energy Energy Efficiency Renewable Energy

0845 009 5652


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All reasonable care has been taken in preparation of this information sheet; all information, recommendations and guidance notes on the use of products are made without guarantees since the conditions of use are beyond the control of Green Energy Doctor LLP (The Company). The information contained in this document and advice arising therefrom is free of charge and accordingly on the terms that no liability nor liability for negligence will attach to the Company or its servant in relation to any such service arising out of or in connection with this information sheet. The prices in this information sheet are for illustrative purposes only. Pricing is subject to a full technical survey and suitability of the property. All non-standard installations and components resulting in additional cost will be highlighted during a technical survey. Any additional costs will be communicated to you. Savings information is based upon approximate figures and were based upon prices at the time of going to print. Actual savings and payback may vary. All descriptions, illustrations, drawings and specifications in this publication present only general particulars and shall not form part of any contract.

Biomass boilers practical guide  
Biomass boilers practical guide