In order to progressively remove its reliance on natural gas operations, an engineering-based
concept study for the electrification of pool heating at the City of Greater Geelong’s Kardinia Aquatic Centre was conducted by the Bridgeford Group. This study analysed existing system operations and developed options for system upgrades, from hybrid to fully electrified, with a focus on energy efficiency as well as analysis of infrastructure limitations.
The centre includes FINA, Olympic, diving, toddler, waterslide and learner pools. The site has high gas consumption, however, the electricity supply is zero-emissions via VECO. The existing heating system was not coping following a move to year-round operation, the pools operated at different temperatures and pool covers were only used on some pools.
Existing system
• 1 x 800 kWth boiler (at end of life)
• 1 x 800 kWth boiler (only five years old)
• Electrical constraints (transformer and supply)
Proposed system
A model of annual pool heat loss and energy consumption was developed and benchmarked that considered evaporation rates, conduction, radiation and convective losses. This enabled production of an annual operating profile to set a baseline for the new required gas and water consumption, prior to considering various electrification options.
A key part of the analysis for defining suitable options was the understanding that although peak capacity of the system might be required on particular warm and dry days, or windy and cool days (when evaporation rates were highest), these time periods represented less than 2% of the annual operational load. Sizing heat pump systems for this peak would not be an efficient use of project funding, as for the majority of the year, the heating requirement was much lower. As a result, Bridgeford Group defined options for electrification that would provide a 90% emissions reduction, half of the peak capacity and near half of the cost of a fully electrified system.
This strategy and outcome enables the City of Greater Geelong to reduce emissions by a similar factor at another recreation centre, maximising emissions reduction for the cost.
Load assessment:
Rather than focusing on 100% electrification (which would necessitate a transformer and feed upgrade) partial electrification was considered. A calibrated pool simulation model was developed to determine optimum heat pump sizing. The model included:
• Directional wind speed
• Sources of heat gain/loss including evaporation, conduction, radiation
• Ability to convert from seasonal to year round
• Calibration to actual energy consumption
• Local weather data (temperature and relative humidity).
Key outputs were:
• Alignment between current equipment sizing and model
• Alignment of baseline energy data
• Pool load driven by evaporation – wind speed or ambient temperature + humidity
• Under 400 kW required for 45% of the year
• Under 1 MW required for 80% of the time.
Based on this analysis, the recommendation was for a smaller hybrid heat-pump system (with option for provisioning infrastructure for future electrification if needed).
Focusing on operation-led design and sizing for partial electrification enabled:
1. Ability to design for ~90% emission reduction for 50% CapEx – lowest cost of carbon reduction and best
marginal pay back.
2. Remaining budget can be used for another electrification project, potentially providing up to x1.8 emissions
reduction of single aquatic centre.
3. Focus on ‘marginal uplift/savings’ compared to BAU asset replacement, which assists in payback.
Installation date
Full design is now in progress for implementation.
Project costs:
$500,000–$750,000
Benefits
Expected reduction of gas-based emissions by 90%
(1000 t CO2-e/year), while the remaining 10% of
the emissions will be offset via renewable energy
sources (generation of electricity via solar).
Lessons learnt
Include cost of carbon for the status quo in the business case and design within constraints of:
• End of life
• Electrical infrastructure
• Pool operation and load
• Pools act as thermal storage system for heat pumps
• Addition of or regular use of blankets drastically reduced energy consumption
• Wind-breaks can be effective in reducing plant size and operational cost