Glowing with green warmth

Pilgrim Hospital in Boston, Lincolnshire, has delivered one of the largest, most complex and successful biomass heating projects in the UK. It’s 3MW steam boiler is an ideal template for how the NHS can apply biomass heating to significantly reduce both carbon emissions and heating costs. With the Renewable Heat Incentive (RHI) massively incentivising biomass heating, a key question for the NHS is how can such a pioneering project be repeated and what lessons must be learnt?

The background
Pilgrim Hospital in Boston operates a 24-hour major Accident and Emergency Department as well as all main specialty services, serving South East and South Lincolnshire. In early 2008, the hospital was still depending on a heavy fuel oil boiler system, which was 40 years old and at the end of its life.

The energy strategy was neither sustainable nor efficient. The Trust was keen to adopt a solution that would ensure the provision of electricity, heating and hot water supplies, whilst simultaneously reducing carbon emissions and utilising sustainable fuels sources as far as possible. The Trust commissioned technical reports to identify a solution.

A further challenge was that the quantity of gas available on the site was limited in comparison to the high demand for heating and the cost to bring further gas supplies to site was prohibitively expensive.

The solution
In April 2008, capital funds were made available from the Department of Health’s Energy and Sustainability Fund and Lincolnshire County Council, under their Green Heat scheme. A solution was designed that made best use of the limited gas supply, whilst delivering significant further benefits. The technology selected was a 3MW biomass boiler integrated with a 526kWe gas fired reciprocating CHP engine (combined heat and power) and conventional steam oil boilers. The installation gives Pilgrim Hospital complete diversity of fuel supply with the base load being met by the biomass boiler and gas CHP engine, and peak demands met by standby fuel oil steam boilers. The control system enabled the complex arrangement to work effectively. The technology combination met all the challenges, providing the Trust with fuel flexibility, a reduction in carbon emissions and operating costs.
The engineering was delivered by the companies Wood Energy and Binder, specialists within COFELY, which functioned as the energy services company on the project. Wood Energy specialise in the design, installation and commissioning of biomass heating in the UK and Binder are Austrian manufacturers of biomass boilers. The delivery team were in constant liaison with United Lincolnshire Hospitals NHS Trust to ensure critical deliverables were met. This partnership and relationship has continued to ensure the ongoing success of the project.
The 15-year agreement for delivery of the energy supply, operations and maintenance services consists of a site team of three full time technicians supported by an operations manager operating on a 24-7 basis and is fully supported with in-house specialist services incorporating energy and sustainability (E&S) and controls. This gives a standard operational maintenance regime; on-going performance monitoring; repair and replacement guarantee; delivery of heat and power; sale of steam, electricity and heat; and complete energy management service.

The boiler
The biomass boiler is able to deliver 3000kg/hour of steam including automatic start up, shut down and de-ashing. Wood chips are transported to the boiler automatically via a walking floor wood chip delivery system (13 metres by eight metres) then onto a fuel conveyor and ram feeder. The heat exchanger is fitted with an automatic cleaning system, ensuring high efficiency operation.  
Key attributes include a 3MW steam raising biomass boiler, which can work at up to 10 barg of pressure and uses an oil injection system to ignite the wood chip on start up. Within the boiler a step grate hearth allows excess moisture to be forced off the wood chip. Such a design is ideal for wet chip fuel with up to 50 per cent moisture content. Clever temperature and air flow controls including lambda exhaust gas monitoring and recirculation to continuously and instantaneously minimise nitrogen oxides (NOx) and maximise burn efficiency.
Particulate emissions are minimised through the use of emission control technology with an exhaust gas cyclone, and there is also an automatic ash removal and ash collection mechanism using a chain conveyor to a large ash bin. Finally, remote control and monitoring using software graphics enables immediate and visual boiler diagnostics, as well as longer term data on boiler output and carbon savings.

This highly automated and technologically advanced boiler is perfect for NHS applications as hospitals have high heating and hot water expenditure that also constitutes a large part of their total carbon footprint. This makes biomass heating an ideal solution for NHS carbon reduction and cost saving initiatives.

Carbon & financial savings  
The overall project has significantly reduced boiler house carbon dioxide emissions by 35 per cent  (excluding imported electricity). The biomass heating element accounts for a significant majority of the carbon savings delivered, and a reduction target of 50 per cent is currently being worked towards.
Energy savings in the order of £400,000 per annum are predicted for Pilgrim Hospital.  Biomass heat is also ‘zero rated’ under the Carbon Reduction Commitment (CRC), so the hospital is saving 265kg of carbon dioxide for every MWhour of oil displaced. The benefits of this are currently £42,000 per annum and are expected to exceed £60,000 per annum.
A new biomass boiler of a similar size to Pilgrim Hospital would be eligible for
2.0p/kWh payment from the RHI. This could equate to £200,000 per annum (depending on boiler run hours), which is additional to the significant financial savings already achievable through biomass heating.

The Trust now has a higher rating in sustainability league tables. The wood fuel used in the biomass boiler comes from either local woodlands that are managed to increase biodiversity or from clean recycled wood sources. The sale of wood chip fuel provides a stable, long term income to the rural economy, helping to better manage and protect fragile natural resources and can reduce the volume of waste wood going to landfill.
Biomass heating is a positive way to support your local community and economy rather than depending on fossil fuels from outside the UK.
The Department of Energy and Climate Change (DECC) designed the RHI to revolutionise the way buildings are heated. This will mean biomass heating is financially the preferred choice in all NHS buildings. These RHI eligible installations may be procured as part of an energy service contract (heat sold on a p/kWh basis as at Pilgrim Hospital), a lease or a direct purchase.
The track record and expertise of the designer, installer and operator are critical to success. Once your RHI project is installed and running efficiently, output needs to be maintained for 20 years. Biomass boilers need regular operation and maintenance, available and responsive biomass engineering expertise and a continuous supply of fuel of the right quality, price and calorific value. Operatives based on site will also need to empty ash bins, order fuel, submit quarterly meter readings to Ofgem and receive regular fuel deliveries.  
This may all seem more complicated than paying a gas bill, but thankfully there are companies out there that have been planning for the RHI for many years and are now ready to deliver your installation, look after it and fuel it for the next 20 years.

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