The Doone Kennedy Hobart Aquatic Centre Energy Systems
The Doone Kennedy Hobart Aquatic Centre (DKHAC) uses different energy sources to maintain a consistent and stable temperature for the pool, heating and domestic hot water systems. Each of these energy sources is described below.
Current energy sources
Current heating system
A unique feature of the DKHAC is the heat source for the heating system that provides heating for the pool systems, space heating and domestic hot water. The existing heating system utilises treated effluent water transferred from the Selfs Point Sewage Treatment Plant to the Blinking Billy Point outfall as the energy source for the water sourced heat pumps. This arrangement allows thermal heat transfer from the treated effluent water to the heating source water.
The heated water is then transferred to a 300,000 litre thermal storage tank. This thermal storage tank acts like a water battery in times of peak water demand, storing heated water for use by the water circuits contributing heat to the pools, space heating and domestic hot water system.
An electric boiler is provided as a backup to the treated effluent / heat pump heating system.
Current DKHAC Photovoltaic (PV) Solar System
The first stage of the photovoltaic (PV) solar cell panel system was completed in December 2015, totalling 400 panels producing 100kW. The second stage was completed in June 2017, totalling 1,041 panels producing 290kW. The predicted annual solar power generation of this system is 370,000 kWhrs.
As of February 2018, this system has produced approximately 100,000 kWhrs of solar power.
The solar power is distributed throughout the centre via the electrical distribution boards and is 100% used onsite. This results in an annual cost saving of approximately $130,000 (or 12.5% or our energy use), with the ‘payback’ expected to be less than 6 years.
At the time of completion, it was the largest roof mounted solar panel installation in Tasmania.
New supplementary heating system
In practical terms, if the existing heat pumps fail for any reason, the useful “battery life” of the thermal storage tanks is only a few hours (depending on heat loads at that time). The thermal storage tanks are also highly inefficient and lose heat through the concrete walls and floor and also through atmospheric vents.
To provide an instantaneous and potentially infinite supply of hot water, the DKHAC is currently installing condensing gas boilers with a total thermal output of 1,200kW to supplement the existing electric heat pump system. This will also allow for decommissioning of the inefficient thermal storage tank system and pumps.
This will result in increased energy efficiency by reducing the required heat circuits and losses from the thermal tanks and vents. Greater efficiency is also achieved by delivering the heated water directly from the heat source to the heat load without mixing with thermal storage tank water.
Future energy mix
Having the option to use any combination of effluent, solar, electric and gas energy, the DKHAC can ensure a stable and reliable energy source to maintain the plant room heating systems, using two sources of renewable energy 24 hours a day, 7 days a week, 365 days a year. This also means the centre can implement demand management to make the best use of the energy sources available to reduce energy cost and lessen the demand on critical infrastructure during peak demand periods.
Through our design and engineering, energy use at the centre has been reduced by approximately 20% since 2010. The improvements discussed above will result in further energy savings in the future.