Wellington, Oct 1 NZPA - New Zealand industries seeking proof for overseas markets of their energy efficiency are starting to benchmark their use of a relatively expensive form of energy -- compressed air.

Energy Management Association executive officer Ewan Gebbie said today that the manufacturing sector has a target of $2 billion annual energy savings within five to 10 years, and a compressed air auditing programme developed by the Electricity Commission will play a significant role.

This will be important because some trade rivals may eventually seek sanctions against countries regarded as not doing enough to combat climate change with lower greenhouse gas emissions and use of fossil fuels.

Compressed air was an expensive form of stored energy, even when a compressed air system operated perfectly, he said. Commonly there are so many inefficiencies that less than 10 percent of the energy input into a compressed air system was being used productively.

Air leakages, inappropriate uses of compressed air, or the way the compressors were controlled, could boost the amount of electricity consumed.

Silver Fern Farms's Belfast plant in Christchurch had cut its annual electricity costs by about $25,000 with improvements to its compressed air systems, by working through the commission's programme.

And other major players in the food sector including Fonterra and Westland in the dairy industry, Affco, and Alliance Group, in the meat industry and NZ Sugar had also been involved with the commission's work, which was aimed at the top 500 industrial users of compressed air.

The nation's first two auditors of compressed air systems have been accredited after completing a course run by Waikato University.

Electricity Commission research has predicted improving compressed air systems can lead to electricity savings of 230 GWh a year -- enough to power 50,000 homes over that time -- and the savings would reduce carbon emissions by 46,000 tonnes a year.

The first 100 "walk-through" assessments of compressed air systems in factories had typically identified potential electricity savings of more than 20 percent.

"It builds awareness with management that the hissing noise they hear down the back of the factory is actually costing them 50c a minute, so they'll fix it straight away" he said.