Mixing Oil and Water

This blog has previously discussed the merit of talking about peak oil in terms of electricity conservation in our Making Up The Difference series (parts 3 and 3A). We’ve also talked about how careless water consumption in America and elsewhere results from the abundance of local sources and pressure to provide at below market value (see here).

Because of all the pumping, managing, and cleaning that must be done to the water supply, wasting potable water is also wasting energy. Just how much energy is wasted will vary drastically, and seemingly almost no information is available on the subject. The one truly comprehensive study found on the subject takes place in Iowa. This should be a good estimate, though the exclusion of special-cases like Arizona and Hawaii means it might underestimate the true nation-wide cost.

The study, put together by Pat Sauer and Anne Kimber, is a comprehensive examination of every municipal water system in Iowa. The overview section lists the relevant means. 1,000 gallons of water can be provided at a cost of only 2.77 kilowatt-hours, and wastewater can be treated at a cost of roughly 1.6 kilowatt-hours per 1,000 gallons1. Water that is used and then returned for treatment would then be consuming 3.37 kilowatt-hours per 1,000 gallons. Remember that ordinary United States consumers use roughly 43,300 millions of gallons per day from their municipal water supply2. That means that a lower bound on the energy consumed by the US providing the water used in homes and small businesses alone is roughly 95,836 barrels of oil per day.3 That means plenty of room to conserve.

Besides being a cruel joke at the expense of the parts of the world lacking potable water, this water waste is also energy waste. Individual users however, are not as much to blame as is the ignorance of economic principles that drives people to believe that per-unit subsidies are preferable to keeping inequality in check. Remember too that artificially cheap municipal water often comes at the expense of infrastructure investment, hurting public water supply quality. Inferior public water is just going to make more people drive to the store to buy heavily packaged bottle water.

  1. Iowa municipal water energy usage.
  2. US water usage (public figure only). [calculation: 43,300 * 1,000,000 * 3.37/1,000 /1700]
  3. As before, the conversion from energy to a barrel of oil equivalent came from this site.

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