Navigant Research Blog

Rethinking Water Use in Buildings

— September 8, 2014

Bad news about the water supply keeps rolling in.  In July, a study on the groundwater in the Colorado Basin found that 53 million acre-feet of water (65 billion cubic meters) had been depleted between December 2004 and November 2013.  The historic drought in the western United States is so severe that it is causing mountains to rise.  And ominous signs of water scarcity are not limited to the United States.  Farmers in Vietnam are converting rice paddies to shrimp farms as the dry season gets dryer and the rising South China Sea turns coastal freshwater ponds salty.  Water scarcity threatens much of the world economy, from the food industry to the mining industry to the petrochemical industry.

Though climate change accounts for a part of the unfolding water crisis, water management practices are driving the problem.  Water has long been treated as a free and inexhaustible raw material.  As a result, it’s used inefficiently.  While great progress has been made in increasing awareness of energy efficiency, water continues to be taken for granted.  Without major changes, two-thirds of the world’s population could be living in water-stressed conditions by 2025.

Water Scarcity and the Built Environment

Buildings account for about 12% of water use in the United States.  Already, water conservation efforts and greater efficiencies in using water have led to a reduction in water withdrawals.  But, for further gains, fundamentally rethinking the built environment is necessary.  For the most part, everything that needs water in a building is provided with potable freshwater.  Similarly, all wastewater is treated the same.  But not everything needs potable water.  And rather than being disposed of, some wastewater can be recycled.  Water from a sink can be reused to flush a toilet.  Water from a bathtub can be used for landscape irrigation.  When water is cheap and abundant, it makes sense to have a single system for all water needs and a single system to dispose of all “used” water.  But meeting all water needs with potable water may soon no longer be an option.

Similar recycling efforts can be achieved with stormwater runoff.  Many municipalities treat stormwater runoff and domestic sewage the same, using a combined sewer system to transport them in a single pipe to a sewage treatment plant (though heavy rainfall or snowmelt can create undesirable outcomes for combined sewers).  Rather than building infrastructure to capture and transport stormwater through gutters and sewers, capturing it to recharge groundwater or for direct nonpotable consumption can directly improve the water situation.  Indeed, the Pacific Institute estimates that urbanized Southern California and the San Francisco Bay region have the potential to increase water supplies by 420,000 to 630,000 acre-feet per year simply by better managing stormwater runoff.

One Word: Graphene

Of course, when we talk about water scarcity, we refer to only freshwater, which accounts for only 2.5% of total global water.  Desalinating abundant seawater is a seemingly attractive workaround, a way to solve water scarcity without the difficult task of changing water use habits.  Unfortunately, desalination, for now, is expensive and energy-intensive.  The most common form of desalination, reverse osmosis, forces seawater through a polymer membrane.  The membrane allows water molecules to pass, but blocks salt molecules.

Graphene, an allotrope (i.e., a different structural form) of carbon, which shows promise in battery technology, quantum computing, health monitoring, and solar cells, could reduce the cost and energy associated with desalinating water.  The gaps in polymer membranes are determined by the physical and chemical properties of the polymer used.  Gaps in graphene must be punched, so they can be sized to reduce the amount of pressure needed to pass water through but still prevent salt from passing through.  Lockheed Martin and the Massachusetts Institute of Technology are both working on overcoming the engineering problems associated with graphene membranes.  Commercial viability may still be several years away, but graphene may make desalination accessible enough to meet the world’s needs for clean water.

 

Silicon Valley Tackles the Energy-Water Nexus

— June 18, 2014

No two systems in the built environment are more tightly linked than energy and water.  It’s hard to identify a pathway of conversion, conveyance, and utility of energy and water that does not touch the other system in one way or another.  This is commonly referred to as the energy-water nexus.  A recent Navigant Research report, Smart Water Networks, touched on this topic, in the context of water network innovations and their link to recent changes in the smart grid.

A recent blog by my colleague Eric Woods emphasized the future trends in water at a global scale.  According to the United Nations, water demand will increase by 55% by 2050, with drastic increases in the manufacturing sector.  At the same time, more than 40% of the global population is projected to be living in areas of severe water stress through 2050.  On the energy side, energy consumption is set to grow as well.  According to the 2013 International Energy Outlook, world energy consumption will grow by 56% between 2010 and 2040, mostly in the developing world.

(Source: U.S. Energy Information Administration)

Stresses on the System

And where do energy and water meet?  For consumers, look no further than your daily shower or dishwasher.  Heating water consumes 7% of commercial and 12% of residential energy in the United States.  With common appliances, it’s clear that making them more water or energy efficient cascades to savings of the other resource.

Another clear linkage in the energy-water nexus is hydropower.  In 2010, 16.1% of the world’s energy was generated using hydropower, and four countries – Albania, Bhutan, Lesotho, and Paraguay – generated all of their power from this source.

Looking back upstream in both energy and water, the linkages are equally impressive.  15% of all water is used for the energy sector.  Conveyance or pumping consumes more than 3% of the world’s energy, and in California alone, 7.7% of energy is used for water infrastructure.  Both systems are under stress from increases in demand, as mentioned earlier, but also from droughts, energy scarcity, and in some regions, political vulnerability (virtually all major river systems pass through more than one country).

Open Water Dive

Industry is taking notice.

At a recent Silicon Valley Leadership Group Energy and Sustainability Summit, I moderated a panel on how the cleantech space is making strides to manage the energy-water nexus in California and globally.  Chris King from eMeter (a Siemens company) discussed the need for open water data, analogous to the Green Button initiative.   Cynthia Truelove of the Center for Collaborative Policy argued that the disruptive technology that has made Silicon Valley so successful should carry over into creating disruptive policy that enables joint energy-water regulation that accounts for carbon impacts.  David Koller, from the Coachella Valley Water District, chronicled a pilot study that enabled customers to drastically cut down on water by providing them with smart water meters and relevant feedback in their bills.  From Imagine H2O, a water startup accelerator, Scott Bryan identified how WaterSmart, a company in its portfolio, is demonstrating success at becoming the “Opower for water.”  Some utilities are achieving a 5% reduction in residential water use in 6 months.

The discussion highlighted the need for a concerted effort among industry, policymakers, and end users to tackle the multifaceted challenge of the energy-water nexus of the present and the future.

 

Drought-Plagued California Looks to Smart Water System

— February 4, 2014

In drought-stricken California, an effective approach for helping people curb their energy consumption has shown similar results in helping them reduce their use of water.  It could also be a forerunner of similar programs in other regions that suffer from chronic water scarcity.

The 1-year pilot was conducted among residents living within East Bay Municipal Utility District’s (EBMUD’s) service territory, which includes Oakland and its surrounding suburbs.  Results from an independent study showed that when participants received information comparing their water consumption to neighborhood averages, usage decreased by 5% on average.

The pilot employed a “behavioral water efficiency” approach that has been used by numerous U.S. electric utilities to encourage customers to reduce consumption.  Opower, for example, uses this behavioral-based approach for energy utilities.  In EBMUD’s case, the technology provider was WaterSmart Software, which applies analytics and behavioral science tools to crunch data and provide consumers with feedback information and tips for cutting consumption.

Perma-Drought

The 10,000 EBMUD residential customers involved in the pilot received easy-to-comprehend water use reports for their home and compared consumption to similar-sized homes in the nearby area.  There was a control group set up to make sure other factors, like weather or other customer behavior, did not affect the estimated water savings.  It should be noted that the East Bay pilot was the first large-scale implementation of this type of technology by an urban water utility.

The pilot was partially funded by the California Water Foundation, which concluded that this type of behavior-based water use report, if implemented by other water utilities in California, could help meet state requirements to shrink per-capita water use by 20% by 2020.  And with Governor Jerry Brown’s recent declaration of a state of emergency due to drought, wider implementation of this reporting approach could spread rather quickly.

The East Bay study shows that saving water by providing more granular, timely, and actionable consumption data is an approach that can work.  This solution is bound to be used elsewhere in the United States, especially the Southwest and other regions where drought is an ongoing threat.  In a larger context, the pilot strengthens the case for using data analytics to help drive greater efficiency in water systems, as noted in a previous blog and in Navigant Research’s report, Smart Water Networks.  This is not to say upgraded hardware such as smart water meters and leak detecting sensor aren’t helpful, too.  The best practice will be to integrate both big data and smarter equipment to bring greater efficiencies to water systems.

 

New Discoveries Change Notions of Fresh Water

— December 30, 2013

Two new water discoveries have the potential to significantly alter our understanding and future use of this increasingly scarce resource.  One involves semi-fresh water located under the ocean, and the other is a find below the frozen surface of Greenland.

First, scientists have determined that an estimated half million cubic kilometers of low-salinity water (low enough to be turned into potable water) are trapped beneath the seabed on continental shelves around the world, according to a new study published in the international scientific journal Nature.   The amount of potentially useful water is staggering: a hundred times greater than the amount extracted from the earth’s sub-surface since 1900, according to Dr. Vincent Post, the study’s lead author and a professor in the School of the Environment at Flinders University, which oversees Australia’s National Centre for Groundwater Research and Training (NCGRT).

This offshore groundwater has been found off Australia, North America, South Africa, and China.  It could be utilized to supplement existing water sources for coastal cities and surrounding areas, and could potentially sustain some regions for decades. There are two methods of extracting this water, according to Dr. Post:  build an offshore drilling platform and pipe the water to shore, or drill from the mainland or from islands near the aquifers.  Previously, scientists thought this water only existed under rare and special conditions.

Under the Ice

The second discovery was made in Greenland, where researchers drilling through an ice core found something very surprising about 30 feet down: a giant aquifer estimated to be 27,000 square miles, larger than the state of West Virginia.  Details of the discovery were published recently in Nature Geoscience.

The Greenland aquifer is not considered as a water source for human activity; however, the environmental significance of this finding could be very important.  Scientists theorize the aquifer connects to a network of crevasses and streams that flow to ice sheets and helps lubricate the flowing glaciers.  They also suspect that the aquifer acts like a giant storage area, which could burst at some point, sending a large volume of water out of the ice sheet.  It may be a little of both phenomena taking place, according to Richard Forster, a glaciologist at the University of Utah whose students were among those drilling the core.  Forster has applied for more research funding to study the huge aquifer and how it might affect future ocean levels.  Given the amount of water – perhaps more than 100 billion tons – it could be enough to raise global sea levels by 0.4 millimeters, if it all flowed into the sea at once.  The melting of Greenland’s ice sheet adds about 0.7 millimeters of sea-level rise each year, under current conditions, so a 0.4 millimeter increase would be significant.

Uncharted Seas

These revelations come on the heels of the earlier discovery this year of aquifers in Africa, where large underground reservoirs could help ease drought conditions in North Kenya, as noted in a previous blog.

At this point the implications of these two latest discoveries are not fully known, and neither offers a panacea for the many issues surrounding water.  One could be a big boost for coastal areas in need of additional water sources, and the other could help deepen our understanding of fluctuating ocean levels.  Both are worthy of further study to determine what course of action, if any, makes sense.  Clearly, the aquifers under the sea could pay dividends by helping to reduce the effects of drought or water shortages on land.  But it will require careful drilling techniques and, among other things, the application of smart distribution technologies (some of which are described in Navigant Research’s report, Smart Water Networks).  As Dr. Post warns, “These water reserves [under the sea] are non-renewable,” and “we should use them carefully – once gone, they won’t be replenished until the sea level drops again, which is not likely to happen for a very long time.”

 

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