The Energy-Water Nexus Challenge

Water treatment is essential for public health and environmental protection, but it comes with a significant energy cost. In the UK, water and wastewater services account for approximately 3% of total electricity consumption—a figure that represents both a challenge and an opportunity for innovation.

As climate concerns intensify and energy costs continue to rise, water utilities and industrial facilities are increasingly focused on reducing the energy intensity of their treatment processes. At PuriTech Energy, we've been collaborating with water treatment operators across the country to implement innovative approaches that deliver cleaner water with less energy.

The Current Energy Profile of Water Treatment

To understand the opportunity for improvement, we need to first examine where and how energy is used in typical water treatment facilities. The energy profile varies based on the facility type, but generally includes:

  • Pumping: Often the largest energy consumer, accounting for 25-60% of total energy use in many facilities
  • Aeration: Particularly in biological treatment processes, aeration can consume 25-60% of plant energy
  • Chemical systems: Mixing, dosing, and related processes
  • UV disinfection: An increasingly common but energy-intensive treatment method
  • Filtration and membrane systems: Especially energy-intensive in desalination and advanced treatment
  • Solids handling: Processing and transport of treatment residuals
  • Heating and cooling: Facility climate control and process temperature management

Each of these areas presents opportunities for energy optimization, and leading facilities are making remarkable progress by addressing them systematically.

Case Study: Thames Water's Energy Revolution

Thames Water, serving 15 million customers across London and the Thames Valley, has implemented a comprehensive energy optimization strategy across its treatment facilities. At their Mogden Sewage Treatment Works, which processes waste from approximately 2 million people, several innovative approaches have reduced energy consumption by 45% while increasing treatment capacity.

Key initiatives included:

  • Installation of advanced variable frequency drives on pumping systems, reducing pumping energy by 30%
  • Implementation of fine-bubble diffusion aeration systems with real-time dissolved oxygen controls, cutting aeration energy by 40%
  • Conversion of anaerobic digesters to generate biogas, which now powers approximately 50% of the facility's energy needs
  • Heat recovery systems that capture thermal energy from effluent to heat buildings and process tanks

Perhaps most notably, Thames Water has shifted from viewing their facilities as energy consumers to seeing them as potential energy producers—a paradigm shift that more utilities are beginning to embrace.

"The most sustainable kilowatt-hour is the one you don't use. But the second most sustainable is the one you generate from your own waste streams."

— Olivia Chung, Chief Sustainability Officer, PuriTech Energy

Innovative Technologies Driving Efficiency

Beyond the Thames Water example, several emerging technologies are transforming energy use in water treatment:

Advanced Monitoring and Control Systems

The application of Internet of Things (IoT) sensors and artificial intelligence to water treatment is perhaps the fastest-growing area of innovation. These systems can:

  • Continuously monitor water quality parameters and adjust treatment intensity accordingly
  • Predict demand patterns to optimize pumping schedules and chemical dosing
  • Detect inefficiencies and equipment failures before they impact operations
  • Optimize process parameters in real-time based on changing conditions

One UK water utility implementing PuriTech's smart monitoring system reported a 23% reduction in energy consumption with no decrease in water quality—in fact, compliance metrics actually improved.

Energy-Efficient Membrane Technologies

Membrane filtration is increasingly common in advanced water treatment, but conventional membranes can be energy-intensive. Recent innovations include:

  • Forward osmosis systems that use significantly less energy than reverse osmosis
  • Biomimetic membranes inspired by natural water filtration processes
  • Nanomaterial-enhanced membranes with higher flux rates and lower pressure requirements
  • Self-cleaning membrane systems that reduce energy-intensive backwashing

These technologies are particularly promising for desalination and water reuse applications, where energy intensity has traditionally been a limiting factor.

Energy Recovery Devices

Modern water facilities are increasingly incorporating systems to recover energy that would otherwise be wasted:

  • Pressure exchangers that capture hydraulic energy in high-pressure systems
  • Turbines installed in discharge pipes to generate electricity from flowing water
  • Heat exchangers that capture thermal energy from treatment processes
  • Biogas capture and utilization from anaerobic digestion

Together, these recovery systems can significantly offset the energy footprint of treatment operations. Some advanced facilities now approach net-zero energy operation through a combination of efficiency measures and energy recovery.

Process Optimization: The Low-Hanging Fruit

While new technologies are exciting, many facilities can achieve substantial energy savings through optimization of existing processes. Common approaches include:

  • Hydraulic optimization: Reducing friction losses, optimizing pump selection, and improving pipe design
  • Aeration system tuning: Ensuring oxygen is delivered only where and when needed
  • Chemical optimization: Precise dosing control and selection of less energy-intensive treatment chemicals
  • Load shifting: Moving energy-intensive operations to off-peak hours when possible
  • Equipment maintenance: Ensuring all systems operate at peak efficiency

One regional water utility working with PuriTech reduced energy consumption by 18% simply through optimizing existing systems—with a payback period of less than two years.

Renewable Integration: The Path to Net-Zero Treatment

Beyond reducing energy consumption, many water facilities are integrating renewable energy generation. This approach is particularly effective because:

  • Water treatment facilities often have significant land assets suitable for solar installation
  • Treatment processes with storage capacity can be designed to run when renewable generation is high
  • Wastewater contains embedded energy that can be captured through various processes
  • Many facilities operate 24/7, making them ideal candidates for continuous renewable generation

Severn Trent Water's Minworth treatment works near Birmingham has installed a 5MW solar array that supplies approximately 30% of the facility's electricity needs, complementing biogas generation from their anaerobic digesters. Together, these renewable sources now provide over 50% of the facility's energy requirement.

The Economics of Energy Efficiency

The business case for energy efficiency in water treatment is increasingly compelling. With rising energy costs, carbon pricing mechanisms, and regulatory pressure to reduce emissions, investments in efficiency typically show attractive returns:

  • Process optimization measures often show payback periods of 1-3 years
  • Equipment upgrades typically demonstrate ROI within 3-7 years
  • Renewable energy installations generally pay for themselves within 5-10 years, with decreasing timeframes as technology costs fall

Beyond direct financial returns, utilities are finding additional benefits:

  • Improved operational resilience and reduced vulnerability to energy price volatility
  • Enhanced regulatory compliance as more stringent energy and carbon regulations emerge
  • Positive public perception and stakeholder relations
  • Workforce benefits, as modern energy-efficient facilities often provide better working environments

Implementation Challenges

Despite the clear benefits, several barriers can impede the adoption of energy-efficient practices:

  • Capital constraints: Upfront costs for efficiency upgrades can be substantial
  • Risk aversion: Concerns about new technologies affecting treatment reliability
  • Regulatory frameworks: Some regulatory structures don't adequately incentivize efficiency
  • Knowledge gaps: Limited awareness or expertise in energy management
  • Split incentives: When those responsible for capital investments aren't the same as those managing operating costs

At PuriTech Energy, we've found that addressing these barriers requires a combination of innovative financing approaches, comprehensive training, and clear demonstration of technology reliability.

The Path Forward: Toward Net-Zero Water Treatment

The future of water treatment is moving toward a net-zero energy paradigm, where facilities produce as much energy as they consume. This vision is being realized through a combination of:

  • Aggressive efficiency improvements across all treatment processes
  • Energy recovery from water and waste streams
  • On-site renewable energy generation
  • Integration with smart grids to optimize energy usage timing
  • Decentralized treatment approaches that reduce energy-intensive water transport

Several pilot facilities in the UK are already approaching this net-zero vision, providing valuable templates for broader industry adoption. These pioneers are demonstrating that environmental protection through water treatment doesn't need to come with a large carbon footprint—in fact, the two goals can be pursued simultaneously.

As water utilities and industrial facilities continue their energy efficiency journeys, the potential benefits extend far beyond cost savings. By transforming the energy profile of water treatment, we're contributing to the broader transition to a low-carbon economy while ensuring this essential service remains affordable and sustainable for future generations.