Networked fridges ‘negotiate’ electricity use

The organisation’s Intelligent Energy Research team based at Newcastle has developed a controller that can be retrofitted to any existing refrigerator.

The controller connects the fridges together using a distributed peer-to-peer system, according to Sam West, an engineer at the CSIRO.

“It’s peer-to-peer so there’s no central point of failure and it’s very scalable,” said West.

“We can use any IP-based communication method [to enable the fridges to communicate] – broadband, 802.11, GPRS, 3G – any packet-based technology.”

West told iTnews that each fridge on the network is typically set up to run in a ‘business-as-usual’ mode of operation for an hour or so.

A thermal model for each unit is then built up using machine learning technology that collates a series of on/off signals and outputs a temperature profile for the fridge, according to West.

The model is said to characterise the fridge’s power requirements to allow predictions to be made on when the fridge will require another ‘on’ cycle.

“A lot of people don’t realise that fridges cycle on and off regularly, which means you’ve got a bit of discretion about when they use power,” said West.

The controller developed by the CSIRO enables communication between other fridges on the network and also the power source.

It has the potential to smooth out fluctuations in electricity demand by enabling fridges to manage available power, according to West.

“The fridges work together to decide when to cool down, and thus consume power, based on how much surplus power will be available,” said West.

“They are able to anticipate power shortages and change their running schedules accordingly to use as little power as possible during these times.”

The networked fridges are also able to take ‘surplus’ energy produced by renewable sources such as solar panels and store it in thermal mass inside the unit, said West.

During the day, supplies of electricity generated from photovoltaics can be interrupted by cloud cover resulting in periods of variable power supply. These fluctuations are bad for the electricity grid, said West.

“Rapid variations in electricity flow can destabilise the grid and result in blackouts and other unwanted side-effects, but your fridge can help smooth out these fluctuations if it turns on and off at the right time,” he said.

“For example, the surplus electricity produced by solar panels can be used to lower the fridge temperature a few degrees more than necessary to create a thermal energy store which will keep the fridge’s contents cold during the night.”

West said the technology has been tested as part of a lab trial in Newcastle consisting of seven small fridges and three larger industrial-sized coolrooms.

Lab simulations have shown the technology is capable of supporting 10,000 or more networked units, but West said a commercial partner was needed to enable the CSIRO to conduct a larger scale, real-world trial.

The technology could also be applied to other household appliances such as air-conditioners and tumble dryers.

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