Case Study 2

The ‘Assessing Biomass Feasibility’ project has been largely theoretical in nature. There has therefore been little opportunity to gain first hand experience of the complexities of installing a biomass system. To this end it was decided that it is essential, in terms of methodology development and for Barony College, to examine how such projects have progressed in the past and learn from this experience.

Ron Hill (Energy Officer) of North Lanarkshire Council’s (NLC) Energy Unit was kind enough provide us with this opportunity through a meeting and the provision of a variety of project reports and papers. Using this information the group has completed the following case study. This will present information on the NLC biomass cluster project, links to our biomass feasibility assessment methodology, supply issues, technical analysis of the systems used, and key lessons learned from these projects.

Project Background

North Lanarkshire Council has installed four biomass heating systems in the Cumbernauld area. These comprise of Drumpellier nursery greenhouses, Palacerigg Country Park and Taylor / Calderhead high schools; these were installed by Econergy Ltd. With only minor technical issues the installations in Cumbernauld have proceeded successfully. They are thermal installations of the following ratings:

Some consultation is underway with the installer as to the operation of these boilers within the existing thermal heating circuits. The projects were originally under the jurisdiction of the planning department, with Energy Services being brought onboard at a later date.

It was decided that it would be useful to learn from the experience of these installations before progressing with further woodfuel installations; potential sites being Broadwood Stadium in Cumbernauld and Ravenscraig sports centre in Motherwell. In September 2006 an independent evaluation was delivered from Alistair Nicol of Cadogan Consultants.

Links to ‘Biomass Feasibility Assessment’ Methodology

The NLC biomass cluster project will now be evaluated in the context of the proposed ‘Biomass Feasibility Assessment Schematic’, this is shown below.

In terms of clarifying the standpoint of the organisation the origin of these projects was the council’s planning and environment department. ‘Lanarkshire Biomass’, comprising several agents, undertook the projects. Key input was gained from the Central Scotland Forest Trust (CSFT).

In 2001 CSFT, Scottish Enterprise Lanarkshire, NLC, Scottish Natural Heritage and Forward Scotland joined together to form a steering group and development fund to instigate a cluster of wood fuel heated buildings.

The aim of this was to develop a pilot project that provided a demonstration of how a range of differing public buildings could be heated using biomass. Furthermore Scottish based technical, logistical and business knowledge within the biomass sector would be gained. This can then be transferred and applied in other local authority areas.

Biomass was considered since the heating systems installed at that time were coming to the end of the lifespan and biomass offered the potential of meeting the Council’s environmental objectives and the prospect of lower fuel costs in the future when compared to fossil fuels. Furthermore, according to Ron Hill, “the prospect of capital funding towards a new heating system was an added incentive” (personal communication, February 12, 2007).

In order to gain a greater understanding of biomass as a fuel source visits were made to Austria. Furthermore a consultant was hired.

An example of how demand was calculated is given in the ‘engineering aspect’ section of the Summerlee Project examination. The biomass installations at North Lanarkshire were replacing in situ technology, making quantification somewhat easier. Supply is discussed in detail later on.

In terms of matching the supply and technology, woodchips were utilised since they are more suitable for the size of systems utilised than pellets. Following this decision Austrian Froling Units were selected, these were installed by Econergy Ltd. The cost of these four units was circa £750,000.

It would appear that there was not a sufficiently comprehensive check of legislation pre-project, although there are no definite outstanding issues. Exemptions, authorisations and registrations may have to be sought retrospectively, in particular with regard to smoke control areas and particulates should the boilers be operated at part load.

Significant funding was received from the Energy Saving Trust / Highlands & Islands Enterprise Scottish Community & Householder Renewables Initiative (SCHRI). This is summarised below: -

Building	Total Cost (£)	SCHRI Funding Received	Additional Funding
Calderhead High School	244,904	109,576	Match funding from DTI Bioenergy Capital Grants Scheme & NLC
Drumpellier Nursery	97,977	68,063	As above
Palacerigg Visitor Centre	63,986	49,902	As above

From an instillation perspective the Cumbernauld experience can offer useful pointers:

• That a project manager should be appointed, wholly responsible for the procurement and implementation process
• That boilers should be tested under a variety of load conditions before being accepted
• A clear written description of all intended operating parameters, including times, temperatures and flow rates should be obtained, with diagrams as appropriate
• Plant operating manuals, maintenance manuals, commissioning statements, statutory approvals etc. should all be available in order that they should form part of the project installation and operating records.

Supply Considerations

Current Supply: The woodchips utilised to run the biomass systems installed are currently supplied by Buccleuch Bioenergy Ltd, who manage 10,000 ha of woodlands in the UK in the form of rural estates. The origin of the woodchips utilised at North Lanarkshire is the Scottish Borders; a distance of approximately 80 miles.

This is not ideal from an environmental perspective since, as stated by Ron Hill “a transport distance of over 50 miles seriously erodes environmental benefits” (personal communication, 12 February, 2007) in terms of CO₂ emissions reduction. It was initially planned that Buccleuch Bioenergy would operate a supply depot in the central belt but this, as yet, has not come to fruition.

At present deliveries are made roughly every fortnight. However a heat meter¹ is soon to be fitted which will automatically track fuel use and send information, via a modem, to Buccleuch Bioenergy so deliveries can be made as and when required.

The delivery method is through an Econergy designed hydraulically operated hopper lid illustrated below: -

Fig 1: Reproduced from Description by Ron Hill (personal communication, 12/02/2007).

As the systems utilised by North Lanarkshire Council (NLC) have specified woodchip characteristics (i.e. moisture content and chip size) the need for some kind of random checking methods to ensure fuel supplied matches these was highlighted.

Supply Contract: Cadogan Consultants evaluation states that securing a contract should be among the priorities when planning and implementing a biomass scheme: whether such a scheme is self built, equipment alone is leased or an Energy Services Company (ESCo) is asked to provide a complete solution. Such a contract should clearly stipulate expected and actual performance, all responsibilities, liabilities, contingencies, prices and mediation and/or legal methods for the resolution of any difficulties. Legal advice from an experienced professional is strongly recommended!

A fuel supply contract has been drafted between the two parties but not as yet signed, payments being made per delivery. This is due to the fact that NLC have a commitment that biomass should cost no more, per kWh than gas. This is due to rise in April 2007 (to circa 2.3p/kWh) however with the renegotiated Council-wide supply contract and therefore this caveat may be satisfied.

The draft supply contract underpins all elements of the relationship between ‘Supplier’ (Buccleuch Bioenergy) and Purchaser ‘North Lanarkshire Council.’ This contract is for a supply of heat, in MWh like fossil fuels, and not fuel i.e. tonnes of woodchips. The basic premise of the arrangement being “heat² shall be provided by the supplier from the boiler plant to the purchaser for use in the premises for heating and HW services”.

Buccleuch Bioenergy is responsible for the operation and maintenance (to pipework, valves, pumps, controls etc) of the boiler plant; the plant consisting of the hot water boiler, combustion system, woodfuel handling equipment and the oil backup system. This includes fixing breakdowns and defects. This is because although ‘Econergy’ installed the systems they do not have the operation and maintenance contract however as they are based in England and an engineer is needed on site in two hours if system breaks down.

The onus is also on the supplier to make “all reasonable endeavours to ensure the boiler plant operates cleanly and efficiently”; there is a clear incentive for Buccleuch Bioenergy to do this since the more efficient the system runs the less woodchips will be required to deliver the same amount of energy in MWh.

Woodchips are categorised as “chipped woodfuel derived from uncontaminated woody material only.” Community Services Department wish to recycle the ash in the plant nursery. The waste products are currently being analysed to assess if this is feasible. If it cannot be used it will be removed by the fuel supplier.

It is clear there is a wide myriad of responsibilities which lie with the supplier. This is essential to remove any additional ‘hassle factor’ associated with biomass. Therefore the service offered is the same as with fossil fuels where the bill simply needs to be paid.

To ensure security of supply, vital for schools were pupils can be sent home in unsuitable temperatures and therefore cause large scale disruption, financial penalties are in place for a supply failure. Payments are to be made monthly according to the heat supply meter readings. The contract is for five years to offer security to both parties, cancellation requires one years notice.

Technical Analysis

As mentioned previously North Lanarkshire Council have installed four systems to date; one 50kW, a 220kW and two 500kW rated plant. These are Fröling systems manufactured in Austria.

All four have back up gas systems. These gas boilers are used to bring buildings up to specified temperature rapidly in the morning (16ºC). This greater controllability is due to the fact the biomass system cannot be switched off. Combustion is simply slowed and returning to a higher rate after night slow down has a slow response ‘lead in time’ i.e. it can take several hours to raise temperature from 50º to 80º. Furthermore in summer the biomass system is not utilised and the gas boiler systems supply hot water.

A thermometer is used to measure water temperature and send this information to initiate the biomass boiler. The system operates on a ‘stop and go’ process i.e. there is a temperature sensor in the flow pipeline which measures flow and return temperatures; these are set at 80º and 70º respectively. If the return temperature drops more fuel is moved into the boiler. Control systems (using complex algorithms) are present which can log consumption profiles and predict the ideal time firing is required to ensure to minimum temperature is met. The process is highlighted below:

Fig 2: Reproduced from Description by Ron Hill (personal communication 12/02/07).

The capacity of the biomass systems is 10% larger than the predicted maximum load on site as a safety consideration i.e. they operate at 90% the majority of the time. Although there have been problems with these projects, to be expected with any new venture, they were not related to the technology. Indeed Ron Hill believes the technology is “sound” and “reliable” (personal communication, February 12, 2007).

Project ~ ‘Sumerlee Heritage Centre’ Analysis

In order to gain useful insight into the approach taken by NLC to a potential biomass project the technical appraisal of ‘Sumerlee Heritage Centre’ was reviewed. This covered the proposed biomass system to be utilised at ‘Sumerlee Heritage Centre’, located in Coatbridge. This is currently heated by electricity and gas-fired boilers. The centre intended to turn to a biomass wood-chip boiler for the heating of the two main buildings. These buildings are to be heated 8 hours per day and 7 days a week.

6.1 Engineering Aspect: The annual gas and electricity consumption figures are presented and the electricity used by non-heating appliances is deducted from the sum. This was done by considering that 22.7% of the electricity bill could be allotted to non-heating appliances: how this figure was obtained is not explained. Given the accuracy of the figure, this might have come from the reading of separate electric counters. The figures are then used to estimate the average cost per kWh of heat released.

In terms of energy demand calculations and boiler sizing the heat load for each building was estimated by calculating the U value and the area of the walls, windows, roof etc and by specifying an air change rate for each building. External temperatures were estimated at -1°C and internal temperatures were set at 20°C or 16°C depending on the building. The heat loads were then summed to obtain the power loss. The boiler power rating was chosen on this basis: the closest available rating above the power loss figure.

Annual wood fuel consumption was calculated using the following method. The monthly heating energy required was calculated via the UA values obtained previously and the 20-year average degree days for north-west Scotland. The energy figures obtained were then converted into tons of wood (by considering that the calorific value of wood-chips was equal to 4.3 kWh/kg). This figure was then used to estimate the frequency of wood delivery in winter and summer given that each lorry is loaded with 7.5 tons of wood.

The hot water requirements were estimated to be less than 5% of the total requirements. Consequently, the summer load was considered to be too low to be dealt with by the wood-chip boiler. The boiler is therefore to be turned off in summer and a back-up energy system should provide for the hot-water needs.

Given the buildings which are to be heated and bearing in mind that an easy access for delivery vehicles is necessary, a location for the boiler house was selected. A fuel storage site was also chosen.

6.2 Financial Aspect: Given the annual energy requirements and the cost per kWh of wood and that of the previous gas/electricity mix, the potential savings per year are calculated.

A breakdown of the main costs is provided. The calculations cover the capital cost (boiler cost, boiler house construction, mechanical services etc) and the recurrent yearly cost (wood fuel and boiler maintenance).

6.3 Environmental Aspect: The amount of CO₂ saved thanks to the new biomass boiler was calculated. Besides, other environmental nuisances such as ash processing and noise are briefly alluded to.

Key Findings

From reviewing the projects undertaken by North Lanarkshire Council the following key points have been noted when undertaking a biomass installation. These will be included within our project findings, recommendations and the ‘Biomass Feasibility Assessment Schematic.’

• The technology itself has proved reliable.
• When changing working practices, such as is the case when installing new energy technology, effective communication is essential. Whether between individuals, departments or organisations.
• The provision of funding and ‘in kind’ support of key partners is essential for a successful project.
• The performance of the proposed system should be evaluated under a variety of different conditions (where possible) before acceptance.
• Trying to negotiate a local supplier at the earliest possible opportunity is essential.
• A supply contract should be in place ideally before installation. This should clearly stipulate expected and actual performance, all responsibilities, liabilities, contingencies, prices and mediation and/or legal methods for the resolution of any difficulties.
• Local engineers are essential so as to provide a fast response to breakdowns and defects.
• A fast responding fossil fuel back up system can be useful to reduce lead time (i.e. increased responsiveness for early morning heat) and for hot water provision in summer.

Assessing Biomass Feasibility

Case Study 2

North Lanarkshire Council Biomass Clusters

Introduction