More about this energy-water nexus

You could describe my job as an environmental engineer as getting clean water to people and dirty water away from people. As mentioned in Chapter 2 of “The Carbon Efficient City,” this takes some energy, and so it can be expensive. We try to take advantage of the fact that water goes downhill – especially on the Columbia and Snake rivers, from which the Pacific Northwesterners get the majority of our energy (followed by coal and natural gas).

Wikipedia defines the water-energy nexus as “the relationship between how much water is evaporated to generate and transmit energy, and how much energy it takes to collect, clean, move, store, and dispose of water.” Some quick Google searching turns up some cool emerging technologies to extract energy from water, such as ocean thermal energy conversion.

“The Carbon Efficient City,” the Water Efficiency online journal and others that are for aligning water resource management with climate change action cite strategies such as: public and private investments in water conservation and recycling; increasing the value of a gallon of water in the market; and providing consumer choices that reduce our individual water footprints.

It seems like most of what we hear about increasing water efficiency relates to domestic supply and use. But what about agriculture? Agriculture makes up a much larger portion of our total freshwater use – 70 percent is often the number cited. Running irrigation equipment, creating and transporting fertilizers and pesticides all require water, as well as energy. High-pressure jet sprinklers can be replaced with low-pressure and microirrigation systems, which reduce the amount of water lost to evaporation and use less energy. Sometimes wastewater can be recycled (reclaimed) and used for irrigation –which increases water efficiency, but costs more energy for treatment and distribution.

Agriculture’s efficient water and energy use directly impacts food security, especially with the uncertainty of climate change and the price of fuel. So it seems reasonable to prioritize water use efficiency in agriculture, as well as in domestic water, particularly in developing nations. The Huffington Post Water Blog recently explored this global issue, and calls on the U.S. to take a leading role in the solutions, which could include growing specific crops to make the best use of water and energy resources to meet global and local food needs.


Photo credit: U.S. Geological Survey



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