The questions of our individual and societal water footprint and virtual water are of ever increasing importance as we approach peak freshwater in regions around the globe. With all my attention to energy and environmental issues, including more than a little to water issues (including Energy COOL ways to cut one’s own water consumption), I’d never actually tried to calculate my water use. (Just did so, see H2O’s water calculator.) And, while having read on ‘virtual water‘, I remain(ed) somewhat confused about real implications. (Okay, raspberries are 18+ gallons per cup produced except, I wonder, what is the real “virtual water” calculation for those 15 pounds that I gathered with my kids in a wild patch, that we walked to, that has never seen irrigation?)
With knowing that I didn’t “know” this subject well, I welcomed a pre-publication (scheduled for 10 March 2010) chance to look at Thomas Kostigen’s the green blue book, advertised as “the simple water-savings guide to everything in your life.”
Sigh, this review is going to be a short one as the book fell far short of expectations and requirements. Most notably, there does not seem to be any discussion of the intersection of energy and water. We’re not just talking dams, but the water going up in steam (pdf):
In the United States, approximately 89% of the energy produced in power plants is generated by thermoelectric systems, which evaporate water during the cooling of the condenser water
With dams, there is the issue of evaporation.
final result for typical thermoelectric power plants was 0.47 gal (1.8 L) of fresh water evaporated per kWh of end-use electricity. Hydroelectric power plants evaporated 18 gal (68 L) of fresh water per kWh consumed by the end user. Combined, these values give an aggregate total for the United States of 2.0 gal/kWh (7.6 L/kWh).
GOOD magazine’s excellent graphic on direct/indirect household water footprint provides a good visual on how, energy sources impact our water use. The “average” household, as per this graphic, has an energy water use of 255 gallons/day using nuclear power as source or 24.5 gallons with solar power. (Honestly, don’t know where the 24.5 gallons comes from if this is rooftop PV.) Moving from nuclear to solar power provides 10% of GOOD’s example of potential water savings through personal choice in the household. (Note, there is analysis that concentrated solar thermal power (CSTP) plants require more water than nuclear power plants.)
Let’s however, look at this in a slightly different way in terms of that 2 gallons per kilowatt hour average, across the United States, of energy use. In other words, reducing energy demand (whether due to conservation or energy efficiency or a combination) has a direct impact on reducing water requirements. (And, by the way, vice versa. California is somewhat the extreme, but something like 19% of the state’s electricity is dedicated to moving and purifying water. Water at the tap has an energy footprint, just as energy has a water footprint.)
In terms of the blue green book, “in the laundry room” suggests using a machine rather than hand-washing (one handwashed garment using as much water as a machine load), an energy-star front-loader rather than a top-loading washer, and advocates cutting down on the number of loads (full machine). Okay, but what about line drying, rather than using a dryer, to cut on electricity use and, therefore, cut down on water use?
And, the lack of energy as part of the discussion makes me wonder at conclusions/recommendations. For example, the recommendation to “choose a refrigerated air conditioner instead of an evaporative cooler” because “Air conditioner units … use more energy but they save water.” Well, would that be true if we looked at the energy footprint of that larger water use.
the green blue book disappointed this reader and isn’t on the recommended list for any reader.
NOTE: Perhaps they regret it, Rodale provided a pre-publication version of the book for review.