Energy security and sustainable water use in a green economy

World Water Day (WWD), focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources being celebrated each year, on 22^nd March.  In 2014, World Water Day is on "Water and Energy".

Worldwide, 1.3 billion people cannot access electricity, 768 million people lack access to improved water sources and 2.5 billion people have no improved sanitation. Water and energy have crucial impacts on poverty alleviation.

Water and energy are closely interlinked and interdependent. Energy generation and transmission requires utilization of water resources, particularly for hydroelectric, nuclear, and thermal energy sources. Conversely, about 8% of the global energy generation is used for pumping, treating and transporting water to various consumers. An important consideration in the stationary energy sector is the water requirement for electric power generation. Lower water availability in coming decades will increase the risk that there will be insufficient water for this purpose, particularly as energy demand increases. Currently, maximum quantity of water is consumed by the electricity and gas sector, mostly for steam make up and cooling of coal and gas fired power stations. When evaporative cooling is employed, 90 per cent of the water consumption of a power station is used for that purpose. Hydroelectricity is the largest renewable source for power generation and its share in total electricity generation is expected to remain around 16% through 2035. Most of the water used for hydro power generation is returned to the river.

Many industries/ municipalities dispose of waste water into natural fresh water systems. Rivers and lakes can process small quantities of waste that can be broken down by nature. However, when these limits are exceeded, water quality deteriorates and the downstream water is no longer useable without expensive treatment.  Individuals must have clean water for drinking or they fall ill and die (3,900 children die each day due to dirty water; 1.8 million people die every year from diarrhea diseases, including cholera – the equivalent of 15 killer tsunamis each year or 12 Boeing 747 crashes every day). People also need fresh water for cooking, washing, and sanitation. This is possible only with effective and efficient treatment of both industrial and domestic effluents prior to discharging into natural water bodies. Controlling the waste water generation at the source itself can leads to the energy saving. Identifying the best practices those can make a water and energy efficient green industry a reality, few examples to name are, A modern paper mill in Finland has reduced the amount of water used per unit of output greater than 90% during the last 20 years: changing from chemical to thermo-mechanical pulp, and installation of a biological waste water treatment facility that permitted recycling of water; A textile firm in India reduced its water consumption more than 80%, by replacing zinc with aluminum in its synthetic fiber production, by reducing trace metals in waste water thereby enabling its reuse, and also for irrigation by local farmers. A plant converting sugar cane into sugar in Mexico reduced its consumption of water by over 90% by improving housekeeping and segregating sewage from process waste water.

The available options present different opportunities and challenges. Greater use of dry cooling can reduce water consumption in thermal power plants by up to 90 per cent. Few more opportunities to address the energy water challenge, including increasing water use efficiency, recycling plant waste water, dry cooling, and use of purified recycled water, saline water cooling, desalination and regional water management schemes. In addition to these options, introducing the smart network technologies and systems can increase reliability of supply, maximize energy and water delivery efficiency, and provide higher levels of user choice and flexibility. These networks could eventually extend right across the delivery spectrum, from the extraction or collection of the resource, through the chain of processing and distribution at the highest possible efficiency, to its eventual use and recycling. All of this would be enabled by taking advantage of leading edge ICT systems. Water is a finite, renewable resource. The goal is to ensure that finite resources are used effectively, efficiently and in ways that are consistent with long-term sustainability and resilience.

Reference: 

•  Facts and trends- UN Water