Energy Recovery from Wastewater Treatment Plants in the United States: A Case Study
A Water and Marine Sustainability Month Feature Article
Ashlynn S. Stillwell (University of Texas at Austin ), David C. Hoppock (Duke University) and Michael E. Webber (University of Texas at Austin) have published a paper highlighting the potential for energy recovery from wastewater treatment plants through the optimization of collection and use of biosolids and biogas. The abstract to this interesting analysis:This manuscript uses data from the U.S. Environmental Protection Agency to analyze the potential for energy recovery from wastewater treatment plants via anaerobic digestion with biogas utilization and biosolids incineration with electricity generation. These energy recovery strategies could help offset the electricity consumption of the wastewater sector and represent possible areas for sustainable energy policy implementation. We estimate that anaerobic digestion could save 628 to 4,940 million kWh annually in the United States. In Texas, anaerobic digestion could save 40.2 to 460 million kWh annually and biosolids incineration could save 51.9 to 1,030 million kWh annually.
The introduction to this paper reads:
Wastewater treatment plants represent a portion of the broader nexus between energy and water . Collecting, treating, and discharging municipal wastewater to acceptable permit standards requires energy, mostly as electricity, but also as natural gas or other fuels. Nationwide, wastewater treatment represents 0.1 to 0.3% of total energy consumption and within local city and community government, water and wastewater treatment operations are often the largest consumer of energy . Furthermore, energy for wastewater treatment is likely to increase in the future due to increasing population, stricter discharge requirements, and aging infrastructure. Possible future standards for removal of currently-unregulated contaminants, such as pharmaceuticals and personal care products, might require significant increases in energy consumption at wastewater treatment plants . Fortunately, most wastewater treatment facilities can significantly reduce their energy costs, by up to 30% or more, through energy efficiency measures and treatment process modifications . Through optimized aeration and improved pumping alone, wastewater treatment plants could save 547 to 1,057 million kWh annually, reducing overall energy use in the wastewater sector by 3 to 6% . Wastewater treatment process modifications considered in this case study include anaerobic digestion with biogas utilization and biosolids incineration with electricity generation. Our analysis provides a top-level estimate of energy savings within the wastewater sector in the United States via these two process modifications. We first examine potential energy recovery from anaerobic digestion with biogas utilization on a national scale. Since the state of Texas produces and consumes more electricity than any other state in the nation, we then use Texas as a testbed for analysis of energy recovery from biosolids incineration with electricity generation. These energy recovery strategies could help offset the electricity consumption of the wastewater sector and represent possible areas for sustainable energy policy implementation. Our analysis considers energy consumption and potential savings only; the economics of energy recovery from wastewater treatment, while highly relevant, is reserved for a separate analysis. Energy recovery at wastewater treatment plants represents an important policy lever for sustainability. However, to the best of our knowledge, no one has ever created a model of its potential. This work fills that gap.
Read the full paper in PDF format by clicking here.
Citation: Stillwell A.S., Hoppock D.C., Webber M.E. Energy Recovery from Wastewater Treatment Plants in the United States: A Case Study of the Energy-Water Nexus. Sustainability. 2010; 2(4):945-962.
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Check out what others are saying...[...] and the University of Texas at Austin estimates that exposing wastewater to anaerobic digestion could save 628 to 4,940 million kWh annually in the United States. And the potential gains seem even larger for the developing countries, [...]
[...] and the University of Texas at Austin estimates that exposing wastewater to anaerobic digestion could save 628 to 4,940 million kWh annually in the United States. And the potential gains seem even larger for the developing countries, [...]