The water-energy nexus for sustainable cities

We live at an incredible juncture in the history of water management. We are facing new water supply challenges, a growing population that is more globally connected than ever, and dramatic variations in climate and precipitation patterns that have disrupted our definition of “predictable” rainfall.

Because of this, our traditional thinking about water management is changing rapidly.

We are seeing traditionally arid global regions face the dual challenge of accommodating growth while stretching their limited water supplies. These same regions often face deep, prolonged droughts with periods of intense flooding — events that take place almost simultaneously.

And, we’re seeing that North America is no exception, as many sectors of the U.S. are water scarce and flood prone.

So sustainable water supplies, which have always been at the heart of our cities and urban areas, are more important than ever. They are the essential building blocks for economies, health and quality of life.

Throughout history, nearly every major urban area has required policies, planning, engineering, construction and operations of its major infrastructure to be dedicated to bringing “water to the people,” which can be seen from ancient Rome to New York City, Hong Kong to Los Angeles.

A new model

As the world continues to grow, we are facing a population that will reach nine billion within the next generation’s lifetime. This growth is limiting our resources and real estate options, and traditional urban growth models no longer meet our cities’ needs.

While we have traditionally built cities around a center with expanding urban rings, this model is no longer sustainable. Rather, sustainable water supplies must be incorporated into city plans to create a new “smart city” paradigm.

Now we are seeing that our basic infrastructure will need to be created around a “spinal cord” that more efficiently carries critical supplies of water, energy and transportation infrastructure, allowing for individual city “nodes” to tap into this cord, alleviating the need for each new city to create its own, standalone infrastructure and water supply.

Smart city models are already in the advanced planning stages in some areas, especially in India with the Delhi-Mumbai Industrial Corridor. For India in particular, the smart city model offers the ability to meet the challenge of providing for multiple cities with populations that are already in excess of 10 million people.

Desalination

As we move forward, desalination is one very key component to address both the requirements of new smart cities and water scarcity.

If we focus on the key areas of innovation, delivery and energy, we can ensure that desalination is a robust, sustainable solution for the world.

For more than 40 years, desalination has been at the forefront of water treatment technology to meet the needs of water-scarce regions. The presence of oceans immediately adjacent to large urban centers with some of the greatest demand for water has been motivation for the technology in and of itself.

In addition to these thermal desalination plants, we have seen large-scale reverse osmosis (RO) technology proving itself on seawater in water-scarce regions. This same RO technology is commonly used to treat other alternative-source waters, such as brackish groundwater and reuse water, to provide drought tolerant water sources.

However, just implementing these current technologies is no longer enough.

Essential partnership

We need to move toward the next stage of desalination invention, with the “mature” industry — including engineers, manufacturers, regulators and planners — coming alongside the entrepreneurs and innovators who are now driving the industry forward.

To bring desalination to market, a combination of planning, regulatory approval, construction ingenuity and community buy-in is required. Partnerships that break down the traditional boundaries between parties are essential. Design-build, design-build-operate, public-private partnerships and other innovative delivery methods are effective at building integrated teams to get the job done. Globally, these delivery options are a reality, and North America is now following the global lead.

Water and energy

A sustainable world involves achieving “water independence,” and it requires that we strive to become energy independent with less reliance on fossil fuels. It is possible to address the water-energy nexus by utilizing renewable and sustainable energy — such as wind, solar and pumped storage — along with technological advancements in seawater desalination and renewable energy.

The combination of desalination facilities, in conjunction with energy generation and storage, is one avenue that looks promising for our future, as the energy currently required to run the desalination process can be mitigated by these couplings.

For example, the newest generation of wind turbines can produce power as inexpensive as four-and-a-half cents per kilowatt hour, while energy recovery within an RO plant is increasing with each new facility, allowing us to reclaim a significant portion of the energy used by the plant.

The need to pair energy and water is great, and thankfully, we have great resources to draw upon. If we work together to couple sustainable, renewable desalinated water with sustainable, renewable energy, innovation and delivery, we can achieve sustainable cities.

Vahid Ownjazayeri is chief growth officer, Design and Consulting Services, AECOM.