Three ways to reduce water industry energy use

Pumping and treating water and wastewater uses a lot of energy, costing water companies huge sums of money and making it harder for them to meet tough economic and environmental targets. Water industry specialist David McCune proposes three innovative ways to make water processes more efficient and less energy hungry.

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Around the world, water companies are under pressure to cut their energy use, not only to reduce costs but also to increase resilience and reduce their environmental impact.

Across the island of Ireland, public water utilities spend an estimated €100 million of their annual operational budgets on energy needed to abstract, treat and pump water and wastewater to and from customers. This produces carbon emissions and ties up money that could otherwise be invested in improving their asset base.

All energy-hungry industries are affected by global energy market fluctuations, leading to uncertainty around operational costs. This uncertainty makes it hard for water companies to deliver affordable and reliable services to customers, impacting on their overall resilience.

Certainty of operational costs and the need to build resilience are two key drivers for water companies to reduce their energy dependence. This is no small challenge considering the island’s continuing population growth and that water companies face increasingly tough environmental standards driven by the Northern Ireland Environment Agency and Environmental Protection Agency. When we also consider the ever-increasing scrutiny of public expenditure, as governed by the Utility Regulator and the Commission for Regulation of Utilities, it is clear that local water utilities need to take a multifaceted approach to cutting their energy use and costs. 

TO REALLY DRIVE DOWN LONG-TERM ENERGY USE, THE INDUSTRY MUST MAKE ITS PROCESSES MORE EFFICIENT.

Northern Ireland Water — NI’s largest electricity user — is uniquely positioned to make a positive impact in cutting the country’s energy consumption and reducing carbon emissions. For example, the company’s recently completed £7 million solar farm at Dunore Point'Belfast Telegraph' is expected to save £500,000 in energy costs and around 2,000 tonnes of carbon every year.

Meanwhile, Irish Water continues its multi-billion euro capital investment programme to bring its aging assets up to current standards to comply with environmental requirements. Across the region there are still towns and villages without wastewater treatment facilities, discharging largely untreated effluent into the environment. Tackling this will inevitably lead to greater energy consumption. But this also presents an opportunity to shape the future and make energy efficiency a key driver from the concept stage of new projects, resulting in long-term efficiency savings. Irish Water has already dedicated significant investment in this area of its operations with approximately 200 distinct energy efficiency projectsIrish Water Annual Report and Financial Statements 2017 progressed in 2017 including pumping, lighting and heating.

While progress is good so far, there is more that can be done. To really drive down long-term energy use, the industry must look at ways to make its processes more efficient. Here are three innovative ways how.

CERTAINTY OF OPERATIONAL COSTS AND THE NEED TO BUILD RESILIENCE ARE DRIVING WATER COMPANIES TO REDUCE THEIR ENERGY DEPENDENCE.

1/ Reuse industrial water

In 2018, the Commission for Regulation of Utilities Water and Energy, CRU Ireland, published Irish Water’s proposals for a new tariff framework which will apply to Irish Water’s non-domestic customers. The framework will ultimately lead to a review of pre-treatment and licensing with corresponding cost impacts affecting hundreds of businesses. For water-intensive industries such as fish production and pharmaceuticals, the potential to re-use water represents a significant opportunity.

AECOM has worked with a paper mill to develop a new system that both recovers water and fibre from its main process and reuses treated effluent as part of its paper production process. Using this system, the paper mill discharges less water back into the sewer or environment and has reduced supplied water by as much as 65 per cent.

This means industry can avoid treating larger volumes of wastewater to increasingly high standards as required by regulators, while continuing to meet discharge consents. The knock-on benefit for water companies is that they too have to treat and supply less water. This provides existing treatment works and networks the extra capacity to cope with future demands such as population growth without having to spend money on costly upgrades.

FOR WATER-INTENSIVE INDUSTRIES SUCH AS FISH PRODUCTION AND PHARMACEUTICALS, THE POTENTIAL TO RE-USE WATER REPRESENTS A SIGNIFICANT OPPORTUNITY.

2/ Invest in more efficient kit

Another way to tackle high energy use is to invest in more energy-efficient equipment. For example, water companies use a lot of electricity to pump air into wastewater, which is needed to treat it. Microbubbles, or miniature gas bubbles, can speed up sewage break down because they have a large surface-area-to-volume ratio.

In partnership with the University of Sheffield, AECOM is testing a fluidic oscillator device, which rapidly pulses air through conventional wastewater treatment diffusers to generate microbubbles, without using more energy. Fast vibrations caused by the fluidic oscillator ‘flick’ air bubbles off the diffuser into the water before they increase in size — a key problem for standard systems. The technology can be easily fitted to existing and new-build wastewater treatment plants. 

65%

A new system developed by AECOM and a paper mill reduces supplied water by as much as 65 per cent and discharges less water back into the sewer or environment.

While still in development, the results indicate a 40 per cent improvement in the rate of oxygen transfer. This significantly reduces the amount of energy used to breakdown the sewage, drastically cutting costs and carbon emissions.

3/ Learn from other industries

For decades, the manufacturing and pharmaceutical industries have been using statistical process control methods, a branch of mathematics, to intelligently measure and monitor their production systems to make them more efficient. It is a transferrable approach.

For example, in the water industry, too much dissolved oxygen (DO) in an activated sludge plant can lead to wasteful electricity consumption. However, too little oxygen reduces the quality of effluent produced. This fine balance is difficult to maintain using current water industry control methods as they do not take into account multiple variables such as the concentration of what enters a system, or equipment wear. Through statistical analysis, which we’re currently applying within the water industry, it is possible to intelligently manage oxygen levels to break down sewage as efficiently as possible — optimising energy use.

This approach gives stretched operational and maintenance teams the foresight to prioritise and direct their resources toward solving issues before failures occur, avoiding potential regulatory penalties. Water companies can also use statistical control methods to determine average failure rates to inform whole-life cost decisions and benchmark equipment, leading to better capital investment risk management decisions. As an example, does process equipment brand ‘A’ cost more in whole-life terms because it needs more manual intervention or energy than brand ‘B’, despite being cheaper to buy? Statistical control can be applied to any control variable, not just DO, including chlorine doses in water networks, pumping station levels and booster pressures in potable mains, to name a few.

WE’RE TESTING A MICROBUBBLE TECHNOLOGY INDICATING IMPROVED OXYGEN TRANSFER OF 40 PER CENT, SIGNIFICANTLY REDUCING ENERGY USED TO BREAK DOWN SEWAGE.