Central Control System
Pressurisation System
Primary Plant Area
Steven's Croft Power Station
Contract Value:
£1,749,897
Client:
EON
Timescale:
Jan 10 - May 11
E.ON appointed Vital Energi to convert Steven’s Croft, one of the UK’s largest dedicated biomass power stations, from an electrical generation plant to a combined heat and power plant, enabling it to provide low carbon heat to one of Scotland's largest sawmills, owned by James Jones and Son's. Vital Energi have developed a heating system powered by steam already available from the Steven’s Croft electricity generation process. The system is delivering significant CO2 and financial savings to James Jones & Son's Ltd.
Steven’s Croft is a £90 million, 44MWe net output biomass steam cycle power station that originally opened as an electricity only generating plant in 2008 producing enough low carbon electricity to power the equivalent of 70,000 homes using biomass as fuel thus displacing 140,000 tonnes of greenhouse gases each year.
E.ON were approached by one of Scotland’s largest independent saw millers and independent timber producers, James Jones & Son’s, who required an efficient heating system for its Lockerbie sawmill which operates one of the largest single kilning sites in Scotland. The kiln site was expanding and faced with increasing fuel bills, James Jones & Son’s investigated alternative forms of heat to displace its existing fuel source, distillate oil, which was both expensive and had a high carbon footprint. The Lockerbie site is located adjacent to Steven’s Croft generating plant, receiving heat energy from the plant instead of installing its own 6MW biomass boiler plant has resulted in the saw mill having much lower set up and operational costs without the disruption & use of valuable production space on site. The arrangement enables James Jones & Son’s to displace around 9,000 tonnes of CO2 emissions* each year.
E.ON appointed consulting engineers to provide an outline design for modifying Steven’s Croft into a heat and power station. A competitive tender process was then conducted to find a company that could offer the best value detailed design and build of the system.
Throughout the competitive tender process Vital Energi was able to offer the most competitive price for the project demonstrating the necessary in-house resources and skills required to provide a turnkey solution for the design, supply and installation of the heating system. With over 20 years experience in delivering major district heating projects, Vital Energi was also able to demonstrate its ability to deliver complex design and build projects to the extremely stringent high quality and safety standards required.
Solution:
Steven’s Croft generates electricity by burning biomass, creating steam which then powers a turbine generator thus creating electricity. A steam pipeline was installed by Vital Energi to transfer steam from the turbine generator system to self contained plant which is housed externally to the main plant turbine building. Within the “Primary Plant” area a shell & tube Primary Heat Exchanger condenses steam to maintain a Medium Temperature Hot Water (MTHW) heating circuit. A steam condensate recovery system was installed by Vital Energi to ensure the quality of the condensate water before returning it to Steven’s Croft for use in the biomass boiler process.
The Primary Heat Exchanger condenses the steam to water transferring up to 6MW of heat energy to the cooler return water from the James Jones process, creating Medium Temperature Hot Water (MTHW). The MTHW it is then transported from the Primary Plant to a Secondary Plant located within the adjacent James Jones & Sons site through 1.3 km of underground pre-insulated pipe which was installed by Vital Energi.
In the Secondary Plant heat energy is converted from the MTHW through a series of secondary plate heat exchangers to the Low Temperature Hot Water (LTHW), for compatibility with the cooler water in James Jones and Son’s kiln heating system. Once the heat energy is drawn from the MTHW the cold water is returned to the Primary Plant adjacent to Steven’s Croft for reheating.
Vital Energi was also responsible for the design, supply and installation of the heating control and associated system software integration into the existing Siemens PS-7 site wide central control. The control system interlinks external control panels also installed by Vital Energi allowing the performance of the entire heating system to be monitored and controlled. Vital Energi also delivered effective training to E.ON’s on-site staff on how to fully utilise the software, allowing E.ON effective future operation and maintenance of the system.
Benefits:
- Reduced carbon emissions for James Jones & Sons Ltd carbon by an estimated 9000 tonnes per year*.
- Financial savings for James Jones & Son’s Ltd by displacing distillate oil, a commodity, with a low carbon, locally sourced fuel.
- James Jones & Son’s have a modern, low carbon heating system with low start up and operational costs.
- Steven’s Croft is benefitting commercially from expanding into the heat supplier market.
Conclusion
The project highlights how Vital Energi’s constantly advancing designs can be applied to make even a modern biomass power plant more efficient. The bespoke system can to be adapted and implemented in other pure generation biomass power stations for residential, commercial or industrial premises. In carrying out the project Vital Energi successfully communicated with both its partners, E.ON and James Jones & Son’s, creating a heating system that suited both of the stakeholder’s requirements. Furthermore, in reducing the carbon footprint of James Jones & Son’s Vital Energi is helping the UK government meet its target of achieving an 80% reduction in CO2 emissions by 2050.
* www.jamesjones.co.uk/index.php/news/detail/lockerbie-further-investment
