Energy use crucial to water sustainability

Policymakers around the world are failing to appreciate the amount of greenhouse gas being created through the water sector's growing energy use, warn researchers from the University of East Anglia (UEA).

In a paper published yesterday (26 June 2011), Professor Declan Conway and Sabrina Rothausen argue that while attention has been focused on sustainable water resource management, the environmental impact of the sector’s use of energy to treat, distribute and heat water, has been poorly understood.

“Pressures on water management include stricter water-quality standards, increasing demand for water and the need to adapt to climate change, while reducing emissions of greenhouse gases (GHG),” said Conway, professor of water resources and climate change.

“The processes of abstraction, transport and treatment of fresh water and wastewater all demand energy. Adapting water management to meet increasing demand, regulatory standards and the effects of climate change will in many cases require greater energy use.”

According to the report, meeting the higher water-quality standards required by the European Water Framework Directive, for example, could increase carbon dioxide emissions by 110,000 tonnes per year.

Alternative water supply systems, treatment technologies or water allocation can also overlook the carbon cost. Desalination, for example, is regarded as a sustainable water management approach but it is very energy intensive.

While moves have been made to meet the government pledge to cut emissions from the water sector by 80% by 2050, the UEA paper argues they exclude the most energy-intensive parts of the water life cycle – it’s end use.

As it stands no regulations or requirements have been created to control GHG emissions from this part of the sector.

“Although end use often has the highest energy use of all water-sector elements, it has not traditionally been seen as a direct part of the water sector and is often unaccounted for in water management and policy,” explained Rothausen.

The study also points to UK building requirements, that do not consider use of water stating that: “Without regulatory pressure, there is a risk that new-build UK housing will have higher GHG emissions from water heating than existing housing.”

Rothausen believes energy use within the sector is likely to continue to grow partly as an unintended policy outcome and that to combat this there needs to be a better understanding of the water sector as a GHG emitter.

“A coordinated view of the water sector will promote more comprehensive assessments of energy use, while standardised methodologies will enable comparisons between assessments of different technologies and processes, and between regions or countries,” she said.

The paper calls on governments to create greater coherence in policy across water and energy use, and concludes that a better understanding of water-energy relationships will help the development of innovative tools and mechanisms to aid in reducing GHG emissions.

The full paper is available online from the journal Nature: Climate Change.