sustain

A fantastic article from Scientific American exploring the intrinsic relationships between water and energy in modern society. The article was written by Michael E. Webber, an assistant professor in Mechanical Engineering at the University of Texas, Austin and the associate director of the Center for International Energy and Environmental Policy. A few highlights from the article (my headings):

Water and Energy

Water and energy are the two most fundamental ingredients of modern civilization. Without water, people die. Without energy, we cannot grow food, run computers, or power homes, schools or offices. As the world’s population grows in number and affluence, the demands for both resources are increasing faster than ever.

Woefully underappreciated, however, is the reality that each of these precious commodities might soon cripple our use of the other. We consume massive quantities of water to generate energy, and we consume massive quantities of energy to deliver clean water. Many people are concerned about the perils of peak oil—running out of cheap oil. A few are voicing concerns about peak water. But almost no one is addressing the tension between the two: water restrictions are hampering solutions for generating more energy, and energy problems, particularly rising prices, are curtailing efforts to supply more clean water.

The Cost of Storing, Treating and Delivering Water

The earth holds about eight million cubic miles of freshwater—tens of thousands of times more than humans’ annual consumption. Unfortunately, most of it is imprisoned in underground reservoirs and in permanent ice and snow cover; relatively little is stored in easily accessible and replenishable lakes and rivers.

Furthermore, the available water is often not clean or not located close to population centers. Phoenix gets a large share of its freshwater via a 336-mile aqueduct from, of course, the Colorado River. Municipal supplies are also often contaminated by industry, agriculture and wastewater effluents. According to the World Health Organization, approximately 2.4 billion people live in highly water-stressed areas. Two primary solutions—shipping in water over long distances or cleaning nearby but dirty supplies—both require large amounts of energy, which is soaring in price.

We use a lot of energy to move and treat water, sometimes across vast distances. The California Aqueduct, which transports snowmelt across two mountain ranges to the thirsty coastal cities, is the biggest electricity consumer in the state. As convenient resources become tapped out, provi­ders must dig deeper and reach farther. Countries that have large populations but isolated water sources are considering daunting megaprojects. China, for example, wants to transport water from three river basins in the water-rich south over thousands of miles to the water-poor north, consuming vast energy supplies. Old-guard investors such as T. Boone Pickens who made their billions from oil and natural gas are now putting their money into water, including one project to pipe it across Texas. Cities such as El Paso are also trying to develop desalination plants positioned above salty aquifers, which require remarkable amounts of energy—and money.

In addition, local municipalities have to clean incoming water and treat outgoing water, which together consume about 3 percent of the nation’s electricity. Health standards typically get stricter with time, too, so the degree of energy that needs to be spent per gallon will only increase.

Water and Power Generation

Nationwide, the two greatest users of freshwater are agriculture and power plants. Thermal power plants—those that consume coal, oil, natural gas or uranium—generate more than 90 percent of U.S. electricity, and they are water hogs. The sheer amount required to cool the plants impacts the available supply to everyone else. And although a considerable portion of the water is eventually returned to the source (some evaporates), when it is emitted it is at a different temperature and has a different biological content than the source, threatening the environment. Whether this effluent should be processed is contentious; the Supreme Court is set to hear a consolidation of cases about the Environmental Protection Agency’s requirements that power plants retrofit their systems to minimize impact on local water supplies and aquatic life.

Cars and Water

Plug-in vehicles are particularly appealing because it is easier to manage the emissions from 1,500 power plants than from hundreds of millions of tailpipes. The electrical infrastructure is already in place. But the power sector swallows water. Compared with producing gasoline for a car, generating electricity for a plug-in hybrid-electric or all-electric vehicle withdraws 10 times as much water and consumes up to three times as much water per mile, according to studies done at the University of Texas at Austin.

Biofuels are worse. Recent analyses indicate that the entire production cycle—from growing irrigated crops on a farm to pumping biofuel into a car—can consume 20 or more times as much water for every mile traveled than the production of gasoline. When scaling up to the 2.7 trillion miles that U.S. passenger vehicles travel a year, water could well become a limiting factor. Municipalities are already fighting over water supplies with the booming biofuels industry: citizens in the Illinois towns of Champaign and Urbana recently opposed a local ethanol plant’s petition to withdraw two million gallons a day from the local aquifer to produce 100 million gallons of ethanol a year. Resistance will grow as ranchers’ wells run dry.

Warning: There is No Replacement for Water

Regardless of which energy source the U.S., or the world, might favor, water is ultimately more important than oil because it is more immediately crucial for life, and there is no substitute. And it seems we are approaching an era of peak water—the lack of cheap water. The situation should already be considered a crisis, but the public has not grasped the urgency.

The public has indeed become more open-minded about the risks of peak oil, which vary from the dire (mass starvation and resource wars) to the blasé (markets bring forth new technologies that save the day). Supply shortages and skyrocketing prices have ratcheted up confidence in the claims of the “peakers.” Policy levers and market forces are being deployed to find a substitute for affordable oil.

What will it take for us to make the leap for water and, better yet, to consider both issues as one? When the projections for declining oil production are overlaid with the increasing demand for water, the risks become severe. Because water is increasingly energy-intensive to produce, we will likely be relying on fossil fuels for pumping water from deeper aquifers or for moving it through longer pipelines. Any peak in oil production could force a peak in water production. Peak oil might cause some human suffering, but peak water would have more extreme consequences: millions already die every year from limited access to freshwater, and the number could grow by an order of magnitude.