Resource analysis: Water and energy as linked resources

Abstract

Energy and water are linked resources. This pilot study examines the relationship between energy and water from a direction opposite to that of studies. We are concerned here with evaluating the energy required to supply and treat water, rather than with the water requirements of energy production. The primary energy requirements for three sectors of water management--municipal water supply, municipal sewage treatment, and water for irrigation--are evaluated. Six major cities, Chicago, Denver, Los Angeles, New Orleans, San Antonio, and St. Louis, are used as indicators of the national trend in energy requirements to supply water to municipalities. Nationwide data provided by the federal Environmental Protection Agency for 1977 and 1990 are used to determine the rate of change of energy required to treat municipal sewage over this period. The energy required to supply water for irrigation is estimated for three regions in the Southwest: Kern County, California; the Texas high plains; and San Carlos, Arizona. Historic trends and prospects for future development are used to estimate future energy requirements for each of these water sectors. The projections are compared to expected increases in national energy consumption. The results indicate that: 1. Regional differences in the amount of energy needed to supply water are very large, increasing in some places and decreasing in others. 2. Significant nationwide increases are likely for the energy required to treat sewage. 3. Noncritical short-term increases will occur in the total energy requirement to supply irrigation water, but after the year 2003, the Southwest faces an extremely difficult choice in balancing its resources of energy, water, and agricultural land, particularly in light of its growing urban demands.