Quantifying the energy required for groundwater pumping across a regional aquifer system

Groundwater pumping can be a substantial source of energy expenditure, particularly in semiarid regions with large depths to water. In this study we assessed the energy required for groundwater pumping in the Denver Basin aquifer system, a group of sedimentary rock aquifers used for municipal water supply in Colorado. In recent decades, declining water levels in the Denver Basin aquifers has resulted in increased pumping lifts and higher energy use rates. We quantified the spatially variable energy intensity for groundwater pumping by analyzing spatial variations in the lift requirement. The median energy intensities for two major aquifers were 1.2 and 1.8 kWh m-3. Considering typical municipal well production rates and household water use in the study area, these results indicate that the energy cost associated with groundwater pumping can be a significant fraction (>20%) of the total electricity consumption for all household end uses. Pumping at this scale (hundreds of municipal wells producing from deep aquifers) also generates substantial greenhouse gas emissions. Analytical wellfield modeling conducted as part of this study clearly demonstrates how multiple components of the lift impact the energy requirement. Results provide guidance for water management strategies that reduce energy expenditure.