Oxford Cold Storage has successfully reduced its electricity maximum demand, network costs and clean-energy charges through the implementation of energy efficiency measures. The company works closely with electricity retailers and energy use monitoring companies to assist with energy procurement and to monitor energy use.
“By adopting energy efficiency improvements, Oxford Cold Storage Company reduced its annual cost of electricity by close to $1 million. Over the past five years the company increased storage capacity by 62% without increasing electricity use. Electricity is a commodity and reducing the amount used results in savings on all charges, the energy costs (kWh), network charges and clean energy charges including the carbon tax. This also resulted in an 8% drop in Maximum Demand.” Gabor Hilton, Engineering Manager, Oxford Cold Storage
Company profile
Oxford Cold Storage is Australia’s largest family owned cold storage company and globally ranks 21st in storage capacity. The company’s Laverton North facility has storage for 150,000 pallets at temperatures between +18°C and -28°C. The new facility currently under construction will increase the total storage capacity to 173,000 pallets when completed in September 2013. The facility has the capacity to freeze daily 12,000 cartons and carcasses of meat.
Improving energy efficiency
During the five year period from 2008 to 2012 the company’s storage capacity was increased by 62% from 576,000M³ to 937,000M³. Innovation and improvements in building design and technology decreased the yearly electricity use by 39% from 59.7kWh/M³ to 37.09kWh/M³. In fact 34GWh of electricity was used both periods during 2008 and 2012. (See chart below)
Electricity procurement
Oxford Cold Storage’s process for procuring electricity involves:
- monitoring projected electricity costs for two to three years using forward prices provided by an energy data service;
- locking into long-term contracts for up to three or four years so clients can be given firm quotes; and
- using an intermediary to assist with periodic tenders for energy supply, assessing offers from various suppliers and checking invoices.
The intermediary charges an annual fee. If mistakes are found in invoicing the intermediary keeps 50% of any savings. Oxford Cold Storage sees this as a small premium that results in total lower costs, than if the company directly analysed and procured the energy themselves.
Energy efficiency improvements – Reducing maximum demand
Through improvements in energy efficiency and the continuous monitoring and controlling the electrical demand during peak times the company reduced its Maximum Demand MD from 5615kW to 5160kW saving $39,000 annually.
The biggest reduction in Maximum Demand was achieved by retrofitting 2,100 High Pressure Sodium 400W lights with the same number of 120W LED lights. These lights are a must for operating inside the cold store shaved 563kW from the MD. In addition the same amount of heat load on the refrigeration plant was removed from the buildings.
Demand management
The company’s level of electricity consumption can be forecast with some certainty due to long term contracts with customers based on past maximum demand and consumption records. Oxford Cold Storage has installed monitoring and control systems that constantly monitors energy use and controls maximum demand. Freezers can remain switched off for long periods, with the duration depending on a range of factors, such as the number of times and duration of doors being opened, blast freezing load, ambient temperatures and humidity.
By switching off the freezer units, it is possible to halve the refrigeration load within 15 minutes. Once a freezer has been switched off for some time it may be necessary to increase energy usage to above the normal operating levels to quickly reduce the chambers to the appropriate temperature.
- Increasing the thermal performance of new storage facilities by using better and thicker insulation and reducing the attic temperatures by improving ventilation
- Reducing the loss of refrigerated air and infiltration of outside air by installing air-locks to the loading dock doors and inflatable airbags to wrap around trucks during loading and unloading
- Solid state LED lights are readily switchable, reduce electricity use by 70% and heat load on the refrigeration by 90%
- Power factor correction equipment;
- Vastly improve screw compressor drive efficiency by retrofitting Variable Frequency Drives (VFDs) to control the rotational speed to adjust the capacity to constantly changing refrigeration demand
- Retrofitting VFDs to all condenser fans to reduce fan speed to adjust condenser capacity to meet demand
- Automating chamber doors to reduce infiltration
State based schemes
Oxford Cold Storage sees advantages in participating in state-based schemes.
They received a subsidy from Victoria’s Energy Efficiency Target (VEET) scheme to install 300 lights which reduced the total cost of their lighting by 15%.
With a subsidy from the Victorian Department of Innovation and Regional Development and the help of City West Water the company has also installed a comprehensive rain water harvesting system to supply water to the refrigeration condensers that saves around 15 million litres of potable water annually.
They also see the Energy Savings Scheme (ESS) in New South Wales as an opportunity to implement additional initiatives with payback periods out to four years. Implementing these additional initiatives, which the company has already identified, could achieve an additional 15–20% energy savings.