Harold McGee, frequent dropper of food science, says that the home cook can prepare pasta using much less water than traditionally called for.
Heartened by the experts' willingness to experiment, I went back to work, this time starting with hot water. I found that it's possible to butta la pasta in 1 1/2 or 2 quarts of boiling water without having the noodles stick. Short shapes just require occasional stirring. Long strands and ribbons need a quick wetting with cold water just before they go into the pot, then frequent stirring for a minute or two.
McGee also comments that the energy equivalent of "250,000 to 500,000 barrels of oil" could be saved per year by using less water and the resulting pasta water is thicker and "very pleasant tasting".