The latest additions to our low carbon campus are projected to help save over £200,000 and 1,270 tonnes of CO2 per year.
The installation of the UEA’s thermal stores has now been completed within budget and on schedule at a total project cost of £600,000. The two large steel vessels, each containing 100,000 litres of heating system water, allow the UEA’s gas boilers and combined heat and power (CHP) generators to be operated at optimum efficiency, reducing cost and carbon emissions.
At 100m3 each, plus 15m3 of water in the connecting pipes, these tanks hold the same amount as the fuel load in a jumbo jet. The Estates Engineering and Infrastructure team see the thermal stores as a key piece of the jigsaw in optimising our on-site energy generation to save as much carbon and money as possible while also delivering our heating and electricity needs.
The thermal stores are connected to the UEA district heating system, a network of pipes that provide heat across the site. This heat is generated as a by-product of our Combined Heat and Power (CHP) engines. Producing our energy on campus is lower carbon than grid electricity because we do not lose any in transmission. By only using grid electricity to top up our requirements, we also minimise the energy used from coal power stations.
UEA uses the same amount of boiler energy as 900 semi-detached houses! With centralised heating plant, we can focus on creating optimal conditions.
Energy Centre 1 (EC1) contains the majority of the campus’s boiler and CHP plant. The efficiency of the 3 gas boilers in EC1 is at a maximum when the boilers are running at 65% of their total output; the total is 6 MW for each boiler. If the heat demand of the campus is greater or less than 65% of maximum output, then boiler efficiency falls. This results in higher cost and carbon emissions for every unit of heat produced. The thermal stores will allow the boilers to run at 65% of output for most of the time, with the stores discharging or charging as necessary as campus heat demand rises and falls. When boiler output exceeds campus heat demand the thermal stores are charged for later use, and when heat demand exceeds boiler output the stores discharge. Increasing the efficiency of gas boilers in EC1 is predicted to save £149,000 per year (although this will change as the cost of gas rises and falls) and 735 tonnes of CO2 per year.
For the new gas CHP engines being installed later in 2016, the thermal stores will play a slightly different role. The CHP engines are large engines of the same type found in cars but instead of turning wheels they turn electricity generators and produce useful heat in the process. The cost of electricity to the campus is at a maximum between 4 and 7pm on weekdays, and so during this period the CHP will be operated to meet as much of the campus’s electricity demand as possible. During this period however, the heat produced exceeds the campus’s heat demand. The campus’s main heat demand always occurs during the morning when residents are showering and buildings are brought up to temperature for the day ahead. The thermal stores will allow heat generated between 4 and 7pm to be stored for use the following morning. CHP-related savings are predicted to be £60,000 (at current gas prices) and 535 tonnes of CO2 per year.
The thermal stores are part of an investment programme that will ensure the UEA’s central plant is of the highest efficiency delivering best value for money heating, cooling and power while at the same time reducing the campus’s impact on the environment.