The Glenrothes Energy Network was an exciting opportunity to take excess heat from the nearby RWE biomass plant and convert it into usable low temperature hot water which is transported to customers through a buried district heating network
“Vital deserve a lot of credit for working to a tight schedule. The network flew in at the end and it was a slick operation. One of the biggest successes was the traffic management. Areas were well controlled and managed and the site compound was well kept. This was highlighted by how little negative feedback there was from the public. It was a very challenging programme of work, but Vital Energi reacted quickly and effectively to any on site challenges and maintained a positive attitude throughout.”
Jonathan Coppock Fife Council
The Glenrothes Energy Network is an exciting public private partnership between Scottish Government, Fife Council and RWE which utilises steam generated as a by-product of electrical generation at the Markinch Biomass CHP Plant to deliver low-carbon heat to houses, businesses and public sector buildings within the Glenrothes town centre. The project makes a significant contribution to reducing carbon emissions in Scotland and received funding from the Scottish Government’s Low Carbon Infrastructure Transition Project (LCITP).
Vital Energi won the contract to deliver the detailed design, and construction of the energy centre and district heating network, creating an ambitious and challenging delivery programme which would see the “Heat On” date achieved in advance of the funding deadline.
This project saw us work with the clients’ professional team to design, supply and deliver the energy centre, 6.2km district heating network and High Voltage ducts with cabling to be installed during future phases. The solution needed to fully integrate with the 55MWe biomass CHP plant and connect a range of buildings which included businesses and blocks of housing in the town centre.
By working closely with all stakeholders, we devised a detailed 63 week, fully integrated procurement, construction and commissioning programme which met all essential milestones.
It was clear from initial conversations that the Council prioritised an approach of keeping disruption to a minimum. Through careful traffic management plans this can be minimised. We worked with one of our long-standing traffic management specialists and the council and were able to create a plan which gave confidence to all stakeholders that much of the potential disruption could be mitigated. We explored all opportunities for the highways affected and options included road closures and diversions, temporary traffic regulation methods such as traffic lights and give way systems. To ensure this plan was carried out effectively our traffic management partners were on call when required and attended site on all days where temporary traffic management measures were being implemented. (During peak hours of 7am-9pm and 3pm-6pm.)
One of the stipulations of Planning was that we would not be able to close a busy roundabout leading to a popular local supermarket and we were able to plan alternative routes to ensure that this road stayed open throughout the project.
A big contribution to meeting the extremely tight programme came from our Pre-fabrication Department in Blackburn which was able to create all building connection skids. Additionally, connecting pipework was prefabricated where possible to minimise hot works in occupied council buildings.
Delivering a Robust, Reliable and Efficient Energy System.
The Glenrothes Energy Network takes steam from the 55MWe RWE CHP biomass scheme which uses recovered wood and a small amount of virgin wood to generate steam, driving a turbine and generating electricity. This facility generates carbon savings of approximately 250,000 tonnes per year. The new energy centre we built is capable of taking up to 4MW of heat for the heat network, with futureproofing measures in place to take a further 2MW in the future. In addition to this the scheme also has a backup heating system for added resilience and to ensure continuity of supply.
One of the issues the project presented was that we would have to “break into” the existing power station services (steam, gas, condensate, demineralised water and trade effluent) to create the connection between the existing RWE power station and the new energy centre. This could only be done during the power stations bi-annual maintenance shut down periods when the power station was not operating. The most challenging of these connections being the break-in to the DN500 fluid category 3 steam line which included extensive planning and verification by a third party notified body inspector. This phase of the project involved cutting a section out of the existing steam pipework and replacing it with a T section which would direct steam towards the energy centre. As this was a particularly important process, all welds were undertaken by a Class 1 welder and performed to American Society of Mechanical Engineers (ASME) standards.
This meant we would not only have to deliver an accelerated programme, but would also rearrange the order of delivery to take advantage of this twice-a-year opportunity. By liaising with the client and relying on our long-standing supply chain, we were able to re-order our project delivery schedule and perform all connecting works within the accelerated timescale.
Whilst there was a backup system to ensure continuity of supply for the heat, the operators of the RWE power station needed to be back online and exporting electricity to the grid immediately after the 2 week shut down. If there was any issues with this side of the project which saw the connection take longer than scheduled then it would result in costly delays for which the power plant operators would need to be compensated.
The steam from the biomass CHP plant is transported via pipework to the energy centre and run through a de-superheater which lowers the temperature so that it can be converted into low temperature hot water. The condensate generated during this process is then pumped back into the biomass CHP plant.
We worked with the client’s professional team to enhance the energy centre, changing the structure from a post beam design to a steel portal structure. By doing this we were able to make significant cost savings by reducing the amount of steel used and the system proved quicker to install, which was a significant benefit given the challenging “heat on” date. One issue facing the project delivery team was that the ground conditions were poor and necessitated an enhanced ground engineering piling solution which required implementation within the original project key dates.
As the energy centre picked up all of the services from the RWE power station (Demineralised water, HV, gas, effluent and heat and condensate) we needed to create a solution to connect the two. Our solution was a services bridge which spanned the 600m. Initially this begins at low level, but raises to a high-level at the energy centre to allow vehicular access.
As the energy centre utilises high pressure steam it was essential that the primary network was constructed to the highest standards. RWE specified pipework to ASME specifications to match the standard of pipework in the power station to ensure the services connecting back to the power station were equal in quality to those in the existing power station process systems. An additional aspect which our design and installation team had to accommodate was, because the energy centre operated with high temperature steam (185oC) and LTHW (105oC), all associated pipework had to be analysed using Caesar II stress analysis software to ensure that the additional expansion due to elevated temperatures was controlled to ensure stresses on pipework and plant were within acceptable limits.
Whilst the electricity generated would be exported to the grid, the heat would be used directly to heat local homes and businesses so it was essential to have a resilient system which would guarantee continuity of supply should the RWE not produce steam. This was achieved with a backup system which included three 4.2MW gas boilers and the energy centre was created with space for a forth 4.2MW gas boiler should the demand increase. We also included two 150m2 thermal stores which will be charged during times of low usage and discharged as the heat is needed to maximise utilisation of power station generated heat
The approach to health and safety was proportionately high, given the nature of the project and the contract called for two full-time health and safety advisors on site with constant input and oversight of the fast track site activities.
Creating a Multi-Utility Solution for Now and For the Future
Before beginning the project it was essential that the route created by our designers was suitable and to do this we undertook extensive research and surveys. We performed a detailed ground radar survey of the network route to ensure there were no undocumented existing utilities and that the route was practical. We then created trial holes at critical points to identify and document existing services. To ensure the building connections could be carried out without major issues we also compiled a dilapidation report to assess the condition of the current internal building connections and our specialist engineers performed surveys for all connected buildings.
This comprehensive approach is essential and in this instance it resulted in us creating an improved design which brought several enhancements including:
All of these improvements were made in partnership with the client’s professional team, working together with the fixed goal of creating an optimal, cost effective solution based on the project’s entire life cycle.
To guarantee progress, and flexibility of programme we have developed a delivery method which utilises working zones. By creating between 5-8 simultaneous constructions civil teams, working with multiple district heating installation teams we can ensure constant progress and should there be a delay in one zone, the team can move to another and works continue.
This in-house expertise extends to our pre-fabrication department, based in Blackburn, which produced the 5 customer interface connections with plans to produce more for the next phase. By undertaking this in house we have maximum control over the quality, scheduling, timing of delivery and it also brings the added bonus of reducing hot works on site, which brings multiple health and safety benefits.
Part of the network involved creating the connections to buildings which were customers of the heat network. We connected four council buildings and future proofed the system to enable easier connection for a client who would be joining the network in the future.
In addition to the below-ground pipework we also installed the primary above ground district heating pipework to the plate heat exchangers and the above ground secondary pipework from the plate heat exchangers to the connection points on the building’s heating and hot water systems. In total we installed packaged customer heat substations and associated ancillary plant work to 4 locations with a further 4 planned for the future phase.
Clients often come with funding which has deadline restrictions and we will work with them to create programmes which ensure heat on dates and project completion dates which meet these needs, but to do this we need to create a robust plan which ensures procurement, in-house labour and supply chain all work together towards a unified goal.
Due to the time constraints of this project we create a fully structured, dedicated team. This allowed us to undertake the majority of works with our in-house expertise, forecasting workload across the 9 month project to guarantee deadlines are met. We engaged with our supply chain at the earliest opportunity to ensure they had sufficient labour resources to meet our requirements, but also surplus labour should the project require it.
Due to this comprehensive approach which focussed on early engagement and long-term planning we were able to meet all deadlines for all elements of the work and, in some instances, far exceed these. The overall project was completed a full week ahead of the completion date, despite the challenging timeframe.
Another important part of our responsibility was the enabling works which were required to modify the existing heating systems such as removing existing plant to ensure connection of the new plant and equipment resulted in a smooth handover with no significant down time for the connected customers and businesses.
Bringing Commercial Rigour to Ensure a Financially Responsible Outcome
We participated in monthly meetings with Fife Council and Balfour Beatty and during these sessions we would review the account and obtain early agreements for any additions or omissions from the original contract value. The project team additionally participated in monthly progress meetings with the client’s team to provide updates on key areas such as Health & Safety, design, programme, key risks and all commercial considerations.
Our Quantity Surveyor presented an update on the amount of money we had spent locally, a key consideration for the Council and grant funders, as well as covering our cumulative figures and an update on the final forecast pf the final account. This meant a constant flow of the latest information, keeping all stakeholders informed and, therefore able to make more informed, better decisions.
Connecting Live, Occupied Buildings Whilst Minimising Down Time.
Whilst new-build project offer a “blank canvas”, retrofit projects often present more technical hurdles as you are working with existing buildings which have live utilities. It is, therefore essential to minimise downtime during the switchover and ensure that any down time is during a period when it causes the least disruption for customers. The project served a number of buildings including:
Timings for the scheduled installation works took into account end users consideration and we implemented a range of measures to mitigate potential issues:
Designing the Handover Process to Benefit the Client
On this project there was a stringent testing procedure to follow to prove the heat and flow delivery prior to handover to satisfy the conditions of the Low Carbon Infrastructure Transition Programme funding.
We then carried out a “walk round” and provided information to the Council and their representatives so they had a comprehensive overview of the project, answered any queries and clarified any issues. As part of the handover process we provided copies of all certificates and created a range of operation and maintenance manuals. Working with the client, we also created a comprehensive range of QA inspection and testing plans. On an average energy centre project this might involve somewhere in the region of six documents, but due to the complexity of this project we produced in excess of 70. On successful completion of the commissioning process we were awarded a six months Operations & Maintenance contract.