ENW recognises that the following sectors and thematic priorities are directly and/or indirectly modified by the energy-water Nexus and thus will be directly impacted by the project and partnership activities, these include:
Water is essential for irrigation of high-value agricultural produce, along with the entire agri-food supply chain. Water is equally essential for cleaning and disinfection (dairy, potatoes etc.) in the food sector. Water is used during primary and secondary processes in the food sector and therefore its management is essential for process optimisation and energy consumption.
Energy is needed to supply and distribute water and food for example groundwater abstraction and surface water pumps require energy to operate. Energy is also needed to power agricultural machinery such as tractors, harvesters and irrigation machinery, as well processing and transport of agriculture produce to market.
There are however many trade-offs which must be considered and carefully managed, for example using water to irrigate agricultural crops when locally abstracted can reduce river flows and by extension hydropower generation potential, as well as create conflict with other sectors for this vital resource including the domestic and industrial market.
Replacing water inefficient irrigation practices and technologies with more efficient pressurised and smart systems may decrease water use but simultaneously increase energy use needed to sustain a network of smart sensors and control systems. Growing bio-fuel crops provides energy benefits, but if they require regular irrigation and compete with other land uses they can increase water demands as well as jeopardize food security.
While the volume of water used during the extraction and processing of coal and other raw materials is relatively low, it can have significant impacts on both the quality and quantity of water resources. Water withdrawal (de-watering) is required for both mining and during the reclamation mined land. Additionally, underground mining may require water to be pumped away which an associated energy has cost. This water may become degraded, contaminated and require treatment, requiring a similar energy cost.
The discharge of pollutants from mining can have significant impacts on the energy-water Nexus which requires appropriate low-energy treatment solutions, capable of addressing point source and diffuse pollution sources. There are however many opportunities for innovation which can simultaneously reduce the water and energy impacts arising from mining and the extraction and processing of other raw materials.
Water reuse technologies are increasingly seen as the solution, simultaneously reducing the need for freshwater withdrawals but also the total water and energy impact of mining. However, these technologies may also have an associated energy cost.
The energy sector requires water for many processes including fuel production, hydro-power generation and the thermoelectric power plant cooling. Water is an essential resource for fuel production which is difficult and costly to substitute and as it becomes progressively degraded, it can create management and disposal challenges. Additionally, oil and gas exploration can negatively impact groundwater aquifers and impact marine and mangrove environments.
The emergence of unconventional energy sources in recent years such as shale gas has had both direct impacts on the energy sector as well the water sector. Demand for water for unconventional fuel production has risen which has had significant impacts in areas with already strong competition for resources, pre-existing water resource issues or areas which have abundant ecological sensitive surface water resources. Increasing energy production will require greater access to freshwater. These considerations must be taken into account during the planning and operation of new energy facilitates, particularly when this concerns the abstraction and discharging of potentially harmful pollutants.
Industrial cooling requires varying degrees of water use depending on the technologies and industrial processes involved. Conventional ‘once-through’ systems use the most water whereas older power plants tend to use closed systems, which can use large amounts of water through evaporative cooling. There are alternatives such as dry cooling, which relies on air rather than water for cooling although this has a lower fuel efficiency and a higher carbon impact, demonstrating the trade-offs and conflicts which exist at the water-energy Nexus.
Water and energy infrastructure is arguably the most essential public services in any city. Both systems are intrinsically linked, a significant portion of energy is consumed for the purpose of pumping, heating and cooling water in the domestic and commercial sector. Electricity utilities can directly support water utilities in helping them to become more energy efficient. There is arguably an untapped potential to improve energy-water management efficiency at the Nexus by integrating real-time monitoring into water and sewage distribution systems.
Smart cities and communities utilise transformative technologies such as machine-to-machine (M2M) communications, data analytics, cloud computing and high speed data networks to manage infrastructure more holistically and in an integrated way. Similar systems can be installed to better monitor and manage residential heat harvesting in domestic and commercial buildings, whilst simultaneously reducing water and energy use. Water and energy utilities are continually looking to improve the efficiency of their network by reducing energy requirements and operating costs.
Wastewater treatment uses a large amount of energy to comply with current discharge consents. Wastewater also contains a wealth of potential resources, which if treated and recovered effectively and be potentially valuable. There is currently a lack of low energy technologies, while the application of renewable energy is currently hindered by low efficiency. Many water treatment processes consumer large amount of energy such as activated sludge. There are however many opportunities for energy recovery and greater energy efficiency including aerobic waste biogas production and the integration of ICT systems which can improve performance and reduce energy consumption.
Water abstraction and conveyance consumers a large amount of energy through pumping from source (ground or surface) to reservoirs and treatment plants. Wastewater treatment processes often require large amounts of energy to process, physically segregate, chemically treat, discharge treatment effluent and landfill sludge. New low energy treatment technologies are beginning to emerge such as reed beds, micro-algae bioreactors and anaerobic ponds.
Until recently, seawater desalination was limited to a countries with predominately desert climates. However, new technological developments combined with a reduction in water production costs has expanded the use of technology into new markets which have traditionally been supplied with fresh water resources. The energy consumption of desalination is still greater than other supply alternatives, however the development of high efficiency reverse osmosis and energy recovery devices and reduced the energy consumption.