Optimization Approaches in the Era of the Water-Energy Nexus

By Pragya Kirti Gupta and Markus Duchon

Conservation of conventional energy and integration of renewable energy resources with advanced energy storage technologies interests many researchers and investors. To support increased energy demand using clean energy resources, the use of advanced techniques will lead to a high impact in the areas such as smart mobility, district-wise temperature control and water management.

The fundamental shift in the area of smart grids must consider the fact that even though the renewable energy is in abundance, the cost for planning and maintaining the advanced infrastructure is still quite high. This trend is evident in our perception in the change of water availability. Water was once considered as free and in abundance. In many parts of the world, now water is conceived as a limited resource with a certain price tag. To serve clean water for free, it is important to make the water processing cheaper. Widespread effort has gone into the research and technology development for energy efficient and sustainable access to water. The limited amount of energy from fossil fuel is driving technological changes in not only energy management but also in water management. This water-energy nexus is most intrinsically linked to the core of sustainability.

Smart grids are expected to support all possible load types. Following the energy management system loads, water management system loads should be considered as the most critical. Advanced and novel techniques are continuously being developed to conserve, treat water and minimize water wastage. These technologies often require uninterrupted power supply and show high-energy demand. Therefore, advanced coupling and modularization of electricity and water infrastructures are required.   Thus far, water management applications have focused on improving the water distribution by enacting faster control actions and conserving the available water by recycling of the wastewater. On the other hand, smart grids have focused on clean energy access by optimal utilization of distributed energy resources (DERs). Design of advanced optimization techniques for managing the water infrastructure using cheap and sustainable energy will result in affordable access to quality water supply. Hence, there is a lot of scope for advanced optimization techniques for the water-energy nexus due to their complementary nature. 

Design of advanced optimization techniques for energy efficiency that deals with the water infrastructure management must consider the infrastructural, operational, environmental and economic constraints. To ensure continuous operation of water infrastructure, related water technologies must be considered as critical services that must be supported at all times. The pervasive deployment of the advanced ICT, especially smart metering, will generate big energy data in terms of volume, velocity, and variety. Use of advanced machine learning and artificial intelligence algorithms can provide extensive benefits in energy efficiency and management. 

Current management of water and energy is carried out predominantly by centralized controlling with limited information access. As the area of distribution network increases, the centralized control is often prone to downtime due to network latency, connection loss, damage, etc. A refinement or reconfiguration mostly requires the shutdown of whole system and leads to overall degradation of performance. Betterment in both water and energy management requires distributed monitoring and controlling of the loosely coupled distributed infrastructure (both water and electrical). A distributed control with a centralized coordination can yield a localized and robust control among loosely coupled infrastructure with a platform for more information gathering and analysis.

Optimization strategies for the water-energy nexus, must identify infrastructure that benefit the population, but without posing threat to their privacy. The energy demand of infrastructure such as the water treatment plant and street lighting which are common to the community should be covered mainly by renewable energy sources, as it does not require information of the individual consumer. The use of storage technologies is essential since renewable energy is not available at all times. Surplus energy can be stored and made available when demand exceeds supply. A framework is required to support this optimized use of energy by monitoring and controlling both distributed electrical and water infrastructure, supported by smart storage infrastructure. 

From the magnitude and complexity of the problems around the water-energy nexus arise the need for interdisciplinary and collaborative research on developing an advanced and unified framework for modeling, computation, concept development and decision making for water/energy resource management. The collaborative research would provide the benefits to the utilities across the value chain. A multi-disciplinary research is required to develop a technological unified framework for hardware-software architecture to integrate advanced technologies such as Internet-of-Things (IoT) and Information and Communication Technologies (ICT) for addressing the challenges of efficient management of water and energy in the smart cities. To develop online monitoring and resource management for improving reliability and quality of a water/energy network in smart sustainable city the following aspects must be considered:

• Integration of on-site distributed clean energy resources and energy storage devices for better network efficiency and reduced carbon footprint.
• ICT interface and IoT devices for online monitoring and management system for improving reliability and quality of a water/energy network.
• Optimization and decision-making algorithms to provide load and energy storage scheduling based on the energy price, demand, load profiles and energy storage status for water/energy network efficiency. 
• Hardware and software platforms to improve energy efficiency and water management by real-time monitoring and demand side resource management.

The water-energy nexus requires a huge amount of initial investment. Coupling of cross commodity infrastructure and the integration of energy storage is a challenge with respect to an optimized usage. The true benefits of this coupling can only be achieved by using ICT to bring intelligence closer to the device, leading to a distributed yet synchronized controlling. In such a system, highly integrated components from different sectors interact with each other to use available resources more efficiently and increase the overall performance. Even though the risks and costs of developing these solutions are high, clean and sustainable water supplies and low carbon energy access are essential for economy and quality of life.

This article was edited by Mehmet Cintuglu.

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