This year’s United Nations World Water Day, taking place March 22, is dedicated to the theme of “Water for Cities: Responding to the Urban Challenge.” Around the world, many cultures are undergoing a tectonic shift from largely agrarian and rural living to dense urban living. According to Triumph of the City, more than half of the global population in 2011 will be urban.
Along with the benefits of urbanization, including lower environmental impact, come challenges such as how to provide large, dense and growing populations with clean water for an increasingly growing middle-class society with corresponding expectations.
Chances are you are at least somewhat aware of the growing water scarcity problem, particularly for urban populations, but if you aren’t, here is a quick recap:
- Under an average economic growth scenario and without efficiency gains, global water requirements will grow from 4,500 billion cubic meters today to nearly 7,000 billion cubic meters -- representing more than half of all the water in Lake Superior and a 50 percent increase -- in only twenty years.
- By 2030, some analysts predict that available water supplies will satisfy only 60 percent of demand.
- According to the World Economic Forum, nearly 60% of the world’s population will be living in cities by that time, causing a shortage of clean water for people and businesses in urban environments worldwide.
- In that same time period, one-third of the global human population will have only half the water required to meet basic needs, a situation that is likely to impact food production and agriculture, which account for more than 70 percent of water usage.
- Ceres, an environmental research and sustainability group, 24/7 Wall St., and the National Resources Defense Council have all stated that 10 of America's biggest cities are in severe danger of water shortages in the relatively near future.
The bulk of the conversation around water today focuses on the scope of the problem, governance and policy. In terms of clean technology, the focus is disproportionately placed on energy over water.
However, now more than ever, a focus on innovation is necessary to tackle our water problems throughout the world. Not only do we need to think about innovation in water processing, but we also need to look through an energy lens when we consider water solutions. Water and energy are deeply intertwined in what is referred to as the 'water-energy nexus.' In short, energy is required to generate clean water and a great deal of water is used to generate energy (accounting for almost 40 percent of all fresh water withdrawals in the U.S., according to NREL). There are some forward-looking cities that are leading on solving the energy-nexus equation -- some out of necessity. These examples are instructive to other communities facing the same issues of growing population, shrinking water supplies and increasing energy costs.
- Ashkelon, Israel boasts the largest desalinization plant in the world, which provides more than 15% of the water needs of Israel from the Mediterranean Sea. This plant is an example of how water-energy innovations can work in concert to reduce cost. Energy costs are greatly reduced by using outgoing effluent to help pressure incoming seawater. As a result of this and other innovations in reverse osmosis, the plant produces clean water at a cost of 60 to 70 U.S. cents/m3 compared to most desalinization plants, which cost out at 80 to 90 cents/m3.
- Singapore recovers a high percentage of its water from domestic use, which it purifies and sells to industry. This allows the island nation to effectively manage a closed loop on industrialized and urbanized water. As a self-contained city state, this measure has helped reduce reliance on water imported from Malaysia and has been deemed an important development for national resource independence. Although primarily produced for industrial use, the water is purified to drinking quality using dual membrane microfiltration and reverse osmosis technologies, and is marketed as bottled water for human consumption under the consumer brand NEWater.
- Chandler, Arizona, as part of its LEED certification process, partnered with Intel to achieve aggressive water conservation goals that would benefit both the business community and the residents of the arid region whose water supply that Intel and other area businesses draw upon. As a result of internally reclaiming much of its own industrial wastewater for uses ranging from its fab to its cooling towers and even its landscaping irrigation, Intel’s Ocotillo campus recycles and reuses upward of 75 percent of its water. Intel has also worked with the city’s own reverse osmosis plant to recharge upward of 3.5 billion gallons of drinking-quality water and put it back into Arizona's aquifers. Over the last ten years, that $100 million water conservation investment has recycled some 90,000 acre-feet of water -- enough water for more than 280,000 homes for a year and the equivalent of all the water that goes over Niagara Falls in 11 hours.
As we can see from these examples, our water problems can’t be solved without the types of innovations that simultaneously reduce the energy impacts of generating clean water, provide new technologies targeted to populations with low-grade sources or infrastructure, and combine a number of technologies together so that any source of water can be converted to any required quality level at an optimized water and energy cost.
For more details on the water-energy nexus as it relates to urban growth, please see “A Different Look at Water Part I – Water for Cities and the Water-Energy Nexus.” http://www.dowwaterandprocess.com/
Snehal Desai serves as the Global Marketing Director for Dow Chemical Company’s Water and Process Solutions Business
 Edward Glaeser. Triumph of the City (New York: Penguin, 2011)
 Snehal Desai, “The Sustainability Challenge: Meeting the Needs of the Water-Energy Nexus” (Whitepaper for Dow Water & Process Solutions, January 2011).
 World Economic Forum Water Initiative, “The Bubble is Close to Bursting: A Forecast of the Main Economic and Geopolitical Water Issues Likely to Arise in the World During the Next Two Decades” (Draft for discussion at the World Economic Forum Annual Meeting, Davos, January 2009).
 Daily Mail Reporter, “Water demand will ‘outstrip supply by 40% within 20 years’ due to climate change and population growth,” Daily Mail, March 1, 2011, accessed March 15, 2011 http://www.dailymail.co.uk/sciencetech/article-1361374/Water-demand-outstrip-supply-40-20-years-climate-change-population-growth.html#