Saving water key to reducing energy use

A report by CSIRO and the Water Services Association of Australia (WSAA) gives a clearer picture of water and energy use in Australia and New Zealand and highlights areas offering potentially significant water and energy savings.

The report, 'Energy use in the provision and consumption of urban water in Australia and New Zealand', shows a strong nexus between water and energy.

“Ensuring a reliable water supply for our cities into the future will require more energy due to increasing populations and the trend to develop new, more energy-intensive water sources like desalination plants, re-use and more distance sources,” said CSIRO Scientist and Project Leader Steven Kenway.

“However, the provision of urban water services uses relatively little energy compared to heating water for residential and non-residential purposes. A 15% reduction in residential hot water use could offset all energy used by water utilities in 2006/07.

“Saving hot water represents a real win-win-win: it cuts energy and water use for consumers, reduces energy demand for utilities and helps households and utilities save money on energy and water bills.”

Looking forward to 2030, the project team considered three water consumption scenarios ranging from 150 through to 300 L per person per day for residential water use, based on a population of 15.8 million for Australia’s major cities, which is currently at 12.5 million.

“Under Australia’s current average consumption, which is 217 L per person per day, total energy use to provide water could increase by up to 130% above 06/07 use, if a mix of desalination, recycling and new surface water sources is used to meet the expected demand,” Kenway said.

“Even with this increase, urban water utilities would only account for 0.3% of the total energy used by Australia’s major cities in 2030.”

WSAA Executive Director Ross Young says the scenarios reinforce the need for the water industry to continue to implement energy-saving initiatives, but also to plan water resources with a clear understanding of where energy and water savings can be made most effectively.

“The urban water industry will continue substantial initiatives already implemented to generate green energy from biogas and hydro-electricity generators and measures to increase energy efficiency. These initiatives have already delivered substantial energy savings in the urban water industry,” Young said.

“This report demonstrates where the ‘low hanging fruit’ may be in terms of reducing energy use and the greenhouse gas footprint of the urban water industry and households.

“Analysis showed that installing a Water Efficiency and Labelling Standard (WELS) 3-star shower rose would cut by 45% both water and hot-water-system energy consumption in households with high water use,” he said.

“Replacing an old WELS 2-star washing machine with a 4-star front loading model would cut energy use by more than half and save 10 kilolitres of water annually, assuming 250 washes a year; 50% of washing on cold-wash cycle and 44.5 kWh/year electrical consumption by pumps and motors.”

Copies of the report are available at: http://www.clw.csiro.au/publications/waterforahealthycountry/2008/wfhc-urban-water-energy.pdf.