Support is key to savings

With the Renewable Heat

Incentive (RHI) on the horizon and other C02 saving initiatives, such as the Carbon Reduction Commitment (CRC) encouraging businesses and private investors to seek more fuel efficient heating solutions, the market for biomass boilers looks set to grow considerably in the next five years.

Whilst biomass technologies are still relatively new to the UK in comparison to Europe, the role biomass boilers have to play in preparing for a future with reduced fossil fuel supplies is an increasingly important one. In the past, it has perhaps been all too easy to take advantage of the rich supplies of coal, oil and gas we have access to in this country.

However, times are changing and with the UK’s natural gas resources predicted to decline massively over the next thirty years, the need for more energy efficient, low carbon heating solutions has risen on the agenda. This is especially the case for commercial applications, where organisations are responsible for generating heat on a much larger scale and have carbon footprints to manage in line with Government guidelines.

Fuel security

From the point of view of fuel security and carbon reduction alone, biomass already makes perfect sense. Compared to most fossil fuels, wood fuel is a competitive source of energy – and when used for heating biomass is the lowest cost form of renewable energy there is on a commercial scale. It is also particularly suitable for use in urban fringe areas, where natural gas may be unavailable and reliance on LPG and oil remains high, unless wood fuel isintroduced.

At present, two of the primary markets for biomass in the UK include rural estates with forestry, and public sector work, whereby new and retrofit heating system installations are directly linked to C02 reduction. The new build sector is also having a major influence on the market for biomass and other renewable technologies right now, as builders have to meet increasingly high levels of the Code for Sustainable Homes.

Meeting demand

From an installation point of view, almost all the commercial biomass boilers Econergy supplies are fitted in conjunction with Buderus fossil fuel boilers and sophisticated controls, which enable the two technologies to work efficiently together. Because of the load profile of any demand, around 80-90% of a building’s heat requirement can typically be met with a biomass boiler sized at 50% to 70% of the peak load requirement, with lower capital cost (per KW output) fossil fuel boilers ideally suited for providing back-up and peak load demand. This gives maximum CO2 emissions reduction per unit of installed cost.

Typically, biomass boilers tend to be installed to provide base load for a building – that’s the heating load the building has most of the time. A condensing or standard efficiency boiler will then be integrated into the heating system to provide back-up for the biomass boiler – the fossil fuel boiler being capable of topping-up what the biomass boiler is not sized to deliver.

This is particularly the case in scenarios where 100% of the building load may only be required for two or three days a year and perhaps 90% of the building load required for five days of the year. In such instances, as there are few days when the building load is very high and biomass boilers are more costly to install, doubling the size of a biomass boiler to cover the peak demand of a few days would not be a cost-effective solution. It can be done but a much bigger boiler and buffer tank or multiple biomass boilers would be required for the system to work efficiently, resulting in an unnecessarily high installed cost.

It therefore makes sense to install a more suitable back-up boiler instead, which can easily handle peak load requirements. Condensing boilers, like the GB162 cascade system from Buderus, are a good option.

They also have a very high turndown rate, which means they have very low working points. This means they can operate for long periods of time in a part-load condition, where their primary function is to back up the biomass boiler from day to day.

High efficiency

Condensing boilers in general are highly efficient and have very low emissions too. This is particularly important when it comes to obtaining planning permission for buildings, as to achieve a good BREEAM rating a building has to have a good source of renewable energy for heating.

Biomass boilers meet BREEAM criteria but any back-up boilers installed as part of a heating system design need to meet minimum requirements for efficiency ratings and low NOx emissions too. From an investment point of view, condensing boilers actually serve to strengthen the biomass package. This type of system in its entirety will usually tick all of the boxes required to gain a good BREEAM rating and planning permission as well.

Whilst condensing boilers are a good partner for biomass boilers, non-condensing oil and LPG boilers are just as suitable – especially for installation in remote locations and where there may be no access to network gas. The point to remember is that, whichever boilers are chosen in a back-up capacity, it is important to make sure they are entirely compatible with the biomass boiler they are being installed alongside.

Take control

Specifying the correct controls to link the two technologies together is essential to ensure this happens. Whatever control system is specified, we would always recommend the biomass boiler takes the lead, so the back-up boiler becomes the secondary heating source. It is also important to ensure the buffer tank installed in conjunction with the biomass boiler is properly controlled within the system too.

With initiatives like the RHI and Carbon Reduction Commitment making renewable technologies a lot more attractive and necessary proposition on a commercial scale, we can expect to see biomass boilers (with the back-up of condensing boilers) gradually becoming more mainstream in the UK.

Certainly, designing systems that feature both technologies is a good way to help investors take the next step toward fuel independence, whilst providing peace of mind for a customer base that perhaps isn’t quite used to biomass technology yet – but will be before too long.

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