A class act for school heating systems
Most schools have sufficient year-round heat load to be ideal candidates for biomass heating. Around 90% of energy for school heating and hot water can be satisfied by biomass although this is a conservative estimate as, in real examples reviewed by the Department for Children, Schools and Families (DCSF), a boiler sized at 50% of the peak could deliver 95% savings in fossil fuel energy use.
With energy prices set to rocket and the recent experience of one of the coldest winters for many years, biomass is certainly cheaper than fossil fuels. But there are also important environmental reasons for schools to consider this renewable energy source.
Acknowledging this, the DCSF is committed to making schools more sustainable. Indeed, it wants all schools to be models of energy efficiency, renewable energy use and water conservation by 2020.
The question is – how? One answer is renewable technology, a solution that the UK Government clearly recognises. It says: “Using on-site renewables in schools provides a visible and dynamic teaching resource for the pupils that can be integrated into the curriculum in the sciences, maths, geography and history. Biomass in particular can be linked with lessons about woodland ecology.
“Heating and hot water needs make up around 60-70% of an existing school’s energy requirements, so if those needs can be met through renewable energy, significant carbon savings can be made. Schools also tend to have sufficient space to accommodate the larger plant room required.”
The DCSF now insists that organisations with which it works on capital school building contracts evaluate them for biomass.
What is Biomass?
Biomass is organic non-fossil material that can be used as a fuel source. Woody biomass can be in the form of direct energy (for example, logs, wood chips and trimmings from woodlands) or derivative (such as bio-fuel and wood pellets). Non-woody biomass can include animal waste, industrial and biodegradable municipal products from food processing and high energy crops such as rape, sugar cane and maize.
The Carbon Trust says: “Biomass is a form of stored solar energy and is available in a number of different forms. These include wood, straw, energy crops, sewage sludge, waste organic materials and animal litter. Although burning biomass releases carbon dioxide to the atmosphere, this is offset by the carbon dioxide absorbed in the original growth of the biomass, or captured in the growth of new biomass to replace the materials used.”
It adds that biomass heating results in low net lifecycle carbon emissions compared with conventional sources of heating such as gas, heating oil or electricity.
Biomass in action
Remeha has supplied its biomass technology to many schools in the UK both as refurbishment and new build projects.
An example of the former is Stradbroke Business and Enterprise College in Suffolk which needed to replace three aging oil boilers. Broag supplied the 370-pupil mixed secondary school near the town of Eye in Eastern England with a 450kW biomass boiler. This will stop the school burning a staggering 45,000 litres a year of gas oil and reduce the carbon emissions of the site by around 120 tonnes annually.
Specified by Suffolk County Council (SCC) and installed by Elyo Services Ipswich branch, the Broag UTSK450kw boiler at Stradbroke College is supplied by Broag-Remeha, and manufactured by Austrian company Gilles.
While the refurbishment contract was being carried out, three separate heating zones were created in the school and the controls were upgraded. The new biomass boiler is connected to a low loss header and its fully controlled modulating combustion means there is no need for a buffer vessel or thermal store.
Indeed, the build quality and ability to work without a buffer vessel are the two main attributes that put this type of boiler above others on the market according to specifier Peter Brown of SCC.
Other advantages of the boiler include its capacity to burn chips or pellets and modulation down to 30% of output, as well as 91-93% efficiency. It also offers automatic feed system, ignition, ash removal and daily cleaning of the heat exchanger.
Nine solar panels are connected to the two HWS calorifiers’ second coils. Out of the heating season, they are complemented by a Broag Quinta 65kW boiler in case the sun doesn’t shine.
Broag also recently completed another school biomass boiler installation, this time a new build contract at the newly constructed Walthamstow Academy – a 677-pupil mixed comprehensive school in Waltham Forest, London. The 120kW Broag biomass boiler on this site is fuelled by compressed wood pellets and, unusually, the boiler is fed from a store situated on the ground floor adjacent to the first floor plant room.
Eco-friendly Broag 610 ECO modulating condensing boilers work in conjunction with the biomass boiler and deliver maximum efficiency and low NOx emissions.
Contractor Franklin M&E Services of Chelmsford, which carried out the installation, was particularly impressed by the high standard, quality and appearance of the biomass boiler and its remarkably good control system.
But it is the environmental benefits of biomass that really make the technology stand out. Biomass pellets have an estimated total carbon footprint equating to 50 to 60kg CO2/MW hr compared with the typical estimated total carbon footprint of 230kg CO2/MW hr from natural gas.
Six ways schools can benefit from biomass heating
Schools are expected to reduce their emissions and improve their environmental performance. A biomass heating system can help them to do this.
Operational cost savings
The costs of biomass fuels are typically lower than fossil fuel.
Less exposure to fuel price volatility
Security of energy supply is a recurrent concern for fossil fuels; geopolitical instability in oil and gas producing regions can threaten availability and lead to unexpected price changes. These are likely to be less extreme with biomass and may also be more predictable if the biomass is sourced locally from known suppliers.
Wider sustainable development benefits
Using biomass fuels for heating can help improve the biodiversity of existing woodlands and provide opportunities for rural employment.
Resources diverted from landfill
Around seven million tonnes of waste woods are produced each year, most of which goes to landfill.
Improved energy performance ratings
Using biomass heating equipment in new or refurbished building stock could help achieve higher ratings in schemes such as BREEAM (Building Research Establishment Environmental Assessment Method) Education, which helps schools set environmental targets.