With downward pressure on greenhouse gas emissions increasing and water security concerns rising, the water-energy nexus is posing big questions about integrated resource management. How might utilities produce more water and energy while using less of both?
Water and energy provision have traditionally been viewed and managed as separate resources. While water utilities need energy and energy companies need water, the interconnectedness of the two resources has typically been under-appreciated and the prospect of joint management largely absent.
But as water resources come under increasing pressure from population growth, shifting consumer demands and climate change, the connection between water and energy, and the impacts each have on the other, are becoming key issues for utilities in what has now become known as the water-energy nexus.
In Australia, the water-energy nexus is significant, with urban water management directly or indirectly influencing more than 8% of Australia’s total greenhouse gas emissions. Australia has typically used its relative energy surplus to offset water shortages, relying on pumping or, more recently, energy-intensive desalination to ensure water supply.
“We’ve just thrown energy at solving a water problem or water at solving an energy problem, but now they’re both constrained,” said Dr Steven Kenway, who is the Water-Energy-Carbon Research Group Leader at the University of Queensland’s Advanced Water Management Centre.
“In Europe they’ve got an energy constraint rather than a water constraint, so the problem is shaping up differently in different places. The water-energy nexus is about how we deal with the next 100 years with simultaneous constraints in water and energy.”
Reconciling the countervailing challenges of the water-energy nexus will require a systems-thinking approach, taking into consideration the impacts and reliance on both resources.
Dr Imran Ahmad, head of the Future Earth Program at the Australian Academy of Science, believes the realities of climate change and its diverse impacts are spurring the change in thinking.
“If you look at the South Australia blackout, stakeholders have realised that they had to take an integrated approach to climate and energy, for instance. That type of systems approach is slowly emerging,” Ahmad said.
The scale and complexity of the water-energy nexus is daunting, involving mining, power generation, utilities, industry, agriculture, residential users and environmental considerations, with many stakeholders simultaneously supplying and consuming either or both resources.
John Thwaites, chair of the Melbourne Water Board of Directors, divides the nexus into three key areas of consideration: water and energy utilities, and how they each use both resources; households and the nexus of water and energy, typically in water heating; and how increasing decentralisation could help address the nexus.
“We are seeing more decentralised water and energy supplies. More people are putting on solar PV; we see shared solar, more distributed water with local capture of storm water, recycled water, and co-generation,” Thwaites said.
There are benefits in addressing the nexus through integrated systems management to drive efficiencies in the use of both resources. Improving energy efficiency in water treatment and distribution has been a focus for water utilities. But moves toward renewables and reducing greenhouse gas emissions will put more pressure on these efforts.
“In the future, with potentially carbon pricing to reduce emissions, there will be a greater business incentive to reduce energy and be more efficient,” Thwaites said.
US-based Cambi Technical Director Bill Barber is an outspoken proponent of the need for water utilities to reinvent themselves for the 21st century, shifting their focus from wastewater treatment to energy and nutrient recovery. Triggering that shift though, he said, will likely require either financial or regulatory pressure.
He said many consumers currently take water services for granted and use them unsustainably, but this can be changed.
“People expect clean water and wastewater treatment as a right and don’t give it any value, which is unfortunate for the utilities themselves,” he said. “But 50 years ago, Singapore’s water industry was very, very far behind; now it’s among the most forward-thinking on the face of the earth.
“That came from the government basically saying energy and water are resources that were undervalued, and they were not going to continue to subsidise them. That creates a huge amount of incentive to save water and energy.”
Barber said solving many water-energy nexus challenges will require strong dialogue between both those working in the industry and regulators.
“People say, ‘We’re going to treat water to this standard, because that’s what we’ve been told to do’. But if industry can speak with regulators about how that standard affects other aspects of the process, then they have the opportunity to better balance local and global pollution.
“You can treat water to an extremely high level, but it might cost 10 times the energy to do that. In a global
picture, is that actually the right thing to do?”
In the mix
One major Australian provider already jointly manages water and power supply: Power and Water Corporation in the Northern Territory (NT). While the small customer base in the NT has facilitated the joint management and provision of power and water, the utility has also been able to collaborate and share in research and technical expertise across both their water and power divisions of the business.
“We’ve got common databases and IT support. In Darwin and Alice Springs, we operate out of common sites, which provides us with both scale and efficiency,” John Pudney, Water Services General Manager at Power and Water, said.
While the utility is able to integrate services and thus work towards reducing duplications, Pudney does point out that it can sometimes be difficult to make a case for reducing water or energy use.
“We have worked with colleagues in the power side to put cases for water efficiency within the power plants, but the difficulty is, without regulation, they will simply look at whether it is good financially, and generally it won’t stack up,” he said.
Yet the kind of streamlining that Power and Water Corporation currently uses can be the basis for power
and water savings that would take some of the strain off Australia’s precious water assets while also helping the nation achieve reductions in greenhouse gas emissions.
With the Victorian Government now requiring water corporations to work towards zero net emissions by 2050, such savings are increasingly vital. California is currently running multiple pilot programs using advanced metering technology across water and power utilities to drive efficiencies in both. Smart water and energy meters have been rolled out across multiple states in Australia, and could be the basis for similar programs.
Importantly, water and power efficiency at the household level has the potential for the largest impact on Australia’s water-energy nexus. While many assume water distribution and treatment are the biggest users of energy in water provision, residential water use accounts for four times the energy consumption of water utilities.
In fact, a 15% saving in residential hot-water heating would offset the entire energy consumption of supplying urban water.
Fit for purpose
Australia faces a particular challenge in the water-energy nexus in that the fossil fuels used to provide electricity are the most water-intensive form of power generation.
Our abundance of coal and natural gas has seen the country lag behind other developed nations in the uptake and shift to renewable sources of energy. But adopting the right types of renewables is key to reducing water consumption in the energy sector, particularly given that Australia has such a harsh climate.
UQ Advanced Water Management Centre’s Steven Kenway said once one factors in the irrigation needs for biofuel crops, or the high rate of evaporation from hydropower dams in Australia’s hot climate, the water savings compared to fossil fuels often aren’t as significant as one would expect. And even though dry-cooling gas-fired power stations might take less water, they also return less water to the system, resulting in a similar net loss of water as traditional cooling techniques.
Wind turbines in combination with pumped-hydro storage and sheets of floating solar cells are possible solutions that fit Australia’s unique climate.
“Floating solar reduces evaporation from water storage, while also providing a cooling effect that means the panels perform better as well,” Kenway said.
Ultimately, it is the complexity of Australia’s water and energy markets that will make integration and co-regulation a significant undertaking. Managing the Murray-Darling Basin is an example of the innate complexity of water management, and the importance of getting it right.
Crises like the South Australian electricity blackout, or the contribution of dry weather patterns and infrastructure outages to blackouts in Tasmania, have led to discussion and investigation that could see a more systems-based approach to managing such sectors, and ultimately that is what is needed to combat the constraints of the water-energy nexus.
“This nexus is important,” the Future Earth Program’s Imran Ahmad said. “You can’t just delineate each separately; water, energy, food – all are important and you need to really look at the integrated picture and then take a policy direction.”
First published in Current magazine February 2017.