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Liverpool college generates its own heat and electricity with innovative CHP, electric and phase change thermal storage

Using electricity and heat generated by the same installation is an effective way to increase efficiency in buildings — and also cut costs. In co-generation systems, the fuel, in this case gas, is used to generate electricity using a small gas turbine and the waste heat is used to heat the building and provide hot water.

Wirral Metropolitan College, near Liverpool, is setting a good example in this field. The college has four campuses located around Birkenhead in the Wirral. By the end of the year, it will be using gas to cover most of its Twelve Quays campuses own day-to-day heat and electricity needs.

Reducing dependence on electricity prices

The sharp increases in electricity and gas prices, in the UK in recent years, make this transition a worthwhile investment for the college. ‘This is a demonstration project which is receiving funding from the local authorities as part of an extremely low energy agenda,’ says George Norrie, Technical Director at Scotia Energy, the project designers and integrators. Wirral Metropolitan College is the first public institution to benefit from a multi-million regeneration programme for the town of Birkenhead, just across the Mersey from Liverpool. Its new Wirral Waters campus is the first building completed as part of the redevelopment.

‘There’s a substantial initial outlay, but in the long term the 12 Quays campus will be able to slash energy consumption, CO2 emissions and costs — we estimate savings of over £55,000 per year after an amortization time of about 6 years,’ says Mr Norrie. This is made possible by co-generation technology, which in this case runs on gas along with thermal heat storage and electrical battery storage. This is much more efficient than, for example, oil or gas boilers.

The initial project assessment also considered using an electric heat pump, but

this was decided against, due to the higher cost of generating heat than when using a gas turbine combined heat and power solution. This also provided greater CO2 savings. The college will now draw minimum power from the public grid and will make particularly efficient use of the gas, which it burns in its own installation. This will also reduce the electrical load on the local electrical infrastructure, allowing additional capacity elsewhere. There will also be significant maintenance savings over the costs for the existing heating system.

Combined plant for optimum efficiency

The college, which has around 3000 students, has installed two 65kWe Combined Heat and Power (CHP) Units and thermal and electrical battery storage as elements of a co-generation plant. One CHP unit will supply heat and electricity around the clock, while the other will only run during the day in winter to best match the heating and electrical demand profiles when students are in class and the heat and electrical consumption is at its highest. The phase change thermal and Tesvolt electrical batteries store energy during periods of low demand and supplement the heating and electrical systems when the demand is high.

The college is in use 40 weeks a year from

Lawrie Wilson, Area Manager UK & Ireland atTESVOLT since 1 April 2018

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7am to 11pm. As the amount of electricity and heat generated over the course of a day does not always correspond to the level of demand, a battery storage system and thermal storage system are in place to absorb surplus quantities and re-supply

them later on. The thermal storage system takes up heat generated by the first, continuously running unit at night and then supplies it during the day as needed. The electrical battery storage system does the same for surplus electricity.

The two co-generation units also give the project an extra layer of financial security. If one of the machines is unavailable, the other can ensure that the supply is maintained until they are both in operation again.

During the summer holidays in July and August, when electricity and heat requirements are much lower, the college will draw energy from the grid and the co-generation plant will be shut down. The low energy demand over the summer makes this more cost-efficient, and it also reduces maintenance requirements and extends the service life of the installations. Depending on the cost of imported electricity in the future it is possible to run the CHP in electrical mode only, by blowing off the heat and generating electricity during the summer if found attractive.

High-performance battery storage system

The battery storage system has a capacity of 134kWh and an output of 60kW, and was supplied by the manufacturer Tesvolt, based in Lutherstadt Wittenberg in Germany. Tesvolt specializes in versatile, high-grade storage systems using Lithium Graphite Nickel Manganese Cobalt (G/NMC). Samsung SDI produces the cells, which are also used in the automotive industry and offer outstanding safety and performance.

‘To ensure balanced energy flows between the various cells during battery charging

Tesvolt battery storage system with a capacity of 134kWh and an output of 60kW. Co-generation technology with gas along with thermal heat storage and electrical battery storage is much more efficient than oil or gas boilers. Photo Credit: Scotia Energy

Wirral Metropolitan College, near Liverpool. Photo Credit: Scotia Energy

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and discharging, we’ve developed a smart control system called the Active Battery Optimizer,’ explains Lawrie Wilson, Area Manager UK & Ireland at Tesvolt. The German manufacturer’s storage systems use active bi-directional control, which individually balances each battery cell, to achieve up to 8000 full charge cycles with 100% Depth of Discharge. This means that the college’s storage system will enjoy a long service life with little need for maintenance. The co-generation plant’s gas turbine also has very few moving parts

and does not require oil changes, only regular filter changes, as the rotor assembly is mounted on air bearings.

A practical example for the experts of tomorrow

Using this energy system to supply the college is cheaper, cleaner, quieter, more efficient and reduces CO2 emissions. In addition, as part of a STEM training program, students will be able to use Scotia Energy’s monitoring and targeting system

to access real time and historical data on the installations performance and learn how they are controlled and operated — a practical example which will help them to prepare for their future careers.

The system will go live when the new term starts this September. ‘The monitoring system data will then show us exactly what the energy and cost savings are and also, which college subjects involve particularly high energy consumption, in order that we can optimize this if necessary,’ explains George Norrie.

The project holds further potential for future electricity cost savings and even profits. For example, the surplus electricity which is generated can be sold to help manage demand and optimize grid frequency. It is intended that DC power the internet for computer systems, electric car charging, solar thermal, solar PV and wind turbines will be added to the college energy mix over the next year or so, making the college a truly integrated Scotia Energy solution for the future.

The college is so excited about the 12 Quays campus technology mix it is already planning a similar system with Scotia Energy for its Conway campus. It is hoped that this Innovative integrated energy solution will be rolled out across the local area for schools, colleges, leisure centres and commercial and public buildings.

www.tesvolt.com

Two 65kWe Combined Heat and Power (CHP) Units will cover most of the day-to-day heat and electricity needs. Photo Credit: Scotia Energy

Wirral Metropolitan College, near Liverpool. Photo Credit: Scotia Energy