Eurobodalla Shire Council and Tweed Shire Council both avoided hundreds of thousands of dollars in energy costs at their water pumping stations by being strategic about where and when they pump water. This project is replicable where any site has high demand (KVA) charges and machinery with flexible operation times. Here they share their learnings and outline tips for other councils wanting to be smart about how they operate their major machinery.
How the Project Began
At both Eurobodalla and Tweed Shire Councils this project was instigated by Council staff keen to investigate ways to reduce energy costs particularly at their water pumping stations and water treatment plants. In the case of Eurobodalla, another key driver was an upgrade to the Shire’s water infrastructure including the Moruya to Deep Creek Dam pipeline and the Northern Water Treatment Plant redevelopment that allowed for more operational flexibility.
A main focus of these projects was avoiding electricity demand costs. Energy distributors charge councils a demand charge (known as a KVA charge) at certain sites for energy being used during each tariff time period – Peak, Off-peak and Shoulder. This charge is in addition to a per kWh charge. Put simply, councils only have to use energy once – even for just for a few minutes – within a tariff period for a demand charge to be triggered. This charge can be quite significant – in Eurobodalla Shire Council’s case, the demand charge at their water pumping station was up to $6,000 per tariff per month on one account.
Therefore a key aim for the two councils was to identify how to avoid triggering demand charges in at least one tariff period, ideally during the Peak and Shoulder periods, which have the highest per kWh charge out of all the tariffs.
Eurobodalla and Tweed Shire Councils crunched some numbers on electricity tariffs and demand charges combined with operational patterns of the pumps and town water needs.
“Various scenarios for using the water pumps were considered in order to work out how to use the least amount of energy and operate at times that cost the least” said Mark Shorter, Eurobodalla Shire Council Sustainability Coordinator.
“Putting all the energy billing information into a spreadsheet that divided consumption and the demand charge into the three different tariff areas, Peak, Off-peak and Shoulder enabled us to chart where our costs were going. Graphing these figures for each water pump made it very obvious to all staff that while per kWh costs and needs remained fairly level, we were incurring large spikes in costs due to triggering demand charges. It really drove it home that it wasn't how much we used but when we used it” said Tim Uttley, Tweed Shire Council Water Unit Costing Officer (see Figures 1 and 2).
The analyses at both councils revealed an opportunity to change all operation times at the water pumping stations to Off-peak. And in the case of Eurobodalla Shire Council, a way to reduce the operation time of various water stations was also identified.
Figures 1 and 2: These graphs outline the cost and demand patterns for one water pump (WPS18) at a Tweed Shire water pumping station. Electricity costs rose in August and September 2013, reflecting the periods where electricity was used during Shoulder and Peak tariff times and demand charges have been triggered.
How Energy Savings Were Achieved
At Tweed Shire Council, the Water Unit Costing Officer Tim Uttley took his analysis of various water pumping sites to the operations team to identify where site operation times could be changed to Off-peak times and new operation schedules were set accordingly. Opportunities mainly lay at the water pumping and water treatment stations where reservoirs could be filled during Off-peak times rather than at the sewer pump stations where regular pumping is required. This has resulted in a considerable amount of energy cost savings – the exact quantity of which will be more evident once some energy bills have been analysed. Tim Uttley said: “In May 2014 our electricity costs were over $30,000 lower than the months preceding the operational changes.”
Eurobodalla Shire Council have avoided around $200,000 in annual electricity charges. by undertaking the following three actions:
- Shifting water pumping and regular pump maintenance to Off-peak times. The change in maintenance schedule has had no significant impact on staff as they were already doing some of their work during Off-peak hours. This has also been done at Tweed Shire Council where routine maintenance is now scheduled to occur on Saturdays. Tim Uttley said: “Our maintenance staff are happy with the opportunity to do overtime and earn extra money, while the cost savings in electricity far out way the overtime payments.”
- Reducing the operation time of various water stations. Council worked out ways to be strategic about which pumping stations to use in order to reduce operation times. Brett Corven, Eurodoballa’s Water and Sewer Divisional Manager said: “We found that significant savings in energy costs could be achieved by optimising the use of the Moruya to Deep Creek Dam pipeline. Despite having to pump further than the much closer Buckenbowra pumping station, the Moruya River pumping station currently delivers water to Deep Creek Dam up to 19% more efficiently… which means we only need to pump for short periods to maintain dam water levels. This allows us to restrict our pumping to Off-Peak periods. These savings result in decreased operating costs that can be passed on to our customers in reduced water charge increases.”
- Changing dam trigger levels so capacity better-matches needs. “We have trigger levels, so if the dam goes below a certain level the pumps will turn on. This level wasn’t matched to capacity needs. We worked out the area’s water demand and thresholds and altered our trigger level accordingly” said Mark Shorter.
Next steps for Tweed Shire Council is to conduct energy audits on all major water treatment and sewage treatment plants to see if there are opportunities to save energy.
Two years on, and Eurobodalla Shire Council continues to save energy costs at their water pumping station. Mark Shorter said: “We continue to mainly operate and maintain the pumping stations during Off-peak periods. Our high demand period is in summer when the population increases with a large number of holiday makers. If we ever need extra water pumped compared to usual and can’t manage to do it in Off-peak, we pump during the Shoulder tariff period – which is a much longer time period than Peak. This allows us to trip only two out of the three demand charges. We also prepare for this higher summer demand in winter by pumping more water into the dam.”
Eurobodalla Shire Council has looked into options for saving further costs at the water pumping station by changing their network tariff structure, however they came to the conclusion it wasn’t worth their while. Mark’s attention then went to other sites where energy costs might be saved. He said: “We only have 18 sites that are contestable and only a fraction have demand charges so we haven’t capitalized anywhere else. Here we are installing solar power and exploring other energy efficiency opportunities instead.”
Tips for Other Councils
This energy-saving project is replicable where any site has high demand (KVA) charges and/or machinery with flexible operation times. Here are some tips from Mark Shorter (Sustainability Coordinator, Eurobodalla Shire Council) and Tim Uttley (Water Unit Costing Officer, Tweed Shire Council).
Figure 3: Energy and energy cost saving process. This took councils around two months – data was analysed and discussed over a period of two weeks, and then the new operation and maintenance schedule was introduced the next month.
- Scenarios to explore are:
- Shifting operations to Off-peak or Off-peak and Shoulder times;
- Reducing operation times (e.g. by swapping which pumps you use or reducing the storage refill trigger level).
- A simple Excel spreadsheet is all you need to interrogate your electricity bills, water needs and operation patterns.
- Look into your Peak, Shoulder and Off-peak charges as well as your demand (KVA) charges. This allows you to work out when you are using energy and what costs you are incurring.
- Document water pump operating times, maintenance times and any other operational patterns and needs to see if they can be shifted to avoid Peak and Shoulder hours. E.g. if your water pumping station has an off-stream water reservoir (tank or dam) then it is likely that water can be pumped to this at any time.
- If you have multiple pumps, then establish their efficiency in kWh/kL pumped to work out whether they can be prioritised over others.
- Also document storage capacity, storage refill trigger levels and LGA water needs (water demand) and make sure they are matched.
- Allow one to two weeks to collect and analyse data.
- Discuss findings with key decision makers and staff at Council, outline potential opportunities and see what ideas they have. Make sure operations staff have the potential to alter operation times.
- Once the schedule has been set up to avoid Peak and Shoulder use, be really strict about not tripping the charge.
Figure 4: Eurobodalla Shire Council water pumping station costs. The purple line graph shows how the average c/kWh has decreased by reducing demand charges and pumping times. It also shows in green how much more Eurobodalla would be paying had they not implemented these measures and given electricity prices have increased over this time period.
Mark Shorter, Sustainability Coordinator, Eurobodalla Shire Council at email@example.com or Tim Uttley, Water Unit Costing Officer, Tweed Shire Council at TUttley@tweed.nsw.gov.au. For assistance in analysing energy tariffs contact Lucy Carew-Reid or Paul Brown from Ironbark.