The Water-Energy Tug of War
Inextricably linked, unavoidably interconnected and, at times, conflicted and conflagrant, the relationship between energy and water is the ultimate duality—polarized and indivisible. Those of us working in the fields of water resource management and/or energy efficiency and reliability know that while our concerns are often interchangeable and our challenges similar, we nevertheless find ourselves operating in two separate spheres, focusing only on our own specific challenges and demands and rarely glancing up to take a look at the big picture.
It’s unlikely most people really understand that it takes a lot of water to generate electricity, and that—conversely—it takes a lot of electricity to deliver the water that flows so easily out of your tap. When you start to think about the energy and resources involved in activities and products that occur far from the faucet, it only takes a few moments to grasp just how much water is imbedded in everything we do, everything we eat, and every product we make or buy.
The complicated relationship between energy and water does not stop at supply and demand. Caught in an unrelenting tug of war, water and energy push and pull each other in a never-ending cycle of supply and demand. Water delivery systems result in greenhouse gas emissions, which, in turn, can aggravate already-fragile environments and disrupt local water supplies. Decreasing water supplies require more extensive water collection and distribution systems, thereby exponentially increasing energy usage. Global climate change is an important player as well, both as an influence on water supply, and as a byproduct of water treatment and delivery. In return, as recent scientific studies continue to show, climate change is responsible for the disruption of water supplies across the globe.
On a positive note, it looks like the national dialogue about water and energy has reached a turning point. Over the summer, the American Council for an Energy-Efficient Economy and the Alliance for Water Efficiency published a white paper focusing on the complicated and codependent relationship between water and energy entitled “A Blueprint for Action and Policy Agenda”. The paper addresses three categories of interest: policy/codes, research, and programs. At the same time, Senator Jeff Bingaman (D–NM) introduced The Energy and Water Integration Act of 2011 (S.1343) for consideration by the full Senate. The bill outlines a set of processes that are designed to illuminate and facilitate the relationship between water efficiency and energy efficiency.
As long as water and energy are intertwined, we must make sure to take into account all possible consequences of any energy policy. For example, it takes about 4 gallons of water to produce 1 gallon of biofuel, including roughly 3.45 gallons of water for every gallon of ethanol. Nuclear power requires 0.62 gallons to generate 1 kWh, and coal is a close second with 0.49 gallons per 1 kWh. And don’t forget the imbedded water in fossil fuel production: A study from the Virginia Water Resources Research Center determined that “Fossil-fuel-fired thermoelectric power plants consume more than 500 billion liters of fresh water per day,” or about 95 liters of water for 1 kWh of electricity. And according to the US DOE, it takes 2 to 2.5 gallons of water to produce 1 gallon of gasoline from conventional crude, and more than 6 gallons of water to produce 1 gallon of gasoline from oil shale.
There are better alternatives. Wind power, for example, consumes about 0.15 gallons per kilowatt-hour, and solar hits just a little higher, with 0.25 gallons per kilowatt-hour
(www.nrel.gov/docs/fy11osti/50900.pdf). Microbial fuel cells offer the best of both worlds—the use of naturally occurring bacteria to convert wastewater into clean water combined with waste-to-energy systems able to produce clean, renewable electricity. As with everything, when it comes to power generation—and the imbedded water that comes with it—there’s a choice between traditionally water-intensive options and smarter, water-lean alternatives
Because of the delicate balance between water and energy, savings at one end result in conservation at the other, but we all know that when there’s disturbance in this interplay, inefficiency takes hold, and we find ourselves faced with wrangling substandard results from a costly and wasteful delivery system. Additionally, until water and energy customers begin to pay the true cost for the resources they are consuming, waste will continue to trump conservation, and true harmony between water resource management and energy efficiency will remain an unattainable dream.
Author's Bio: Elizabeth Cutright is the Editor of Distributed Energy magazine and Water Efficiency magazine