Impact

Facts:

  • In the United States, approximately 62.5 billion gallons of wastewater are treated per day by centralized WWTPs.  Globally, wastewater production is expected to increase by 24% by 2030 and 51% by 2050.
  • Through a network of over 800,000 miles of public sewers
  • The average age of these pipes is 45, while some systems have more than a century-old components. The typical lifespan expected for wastewater pipes is 50 to 100 years.
D Plus

It isn’t surprising that the 2021 Infrastructure Report Card  www.infrastructurereportcard.org  gave the wastewater infrastructure a D+.

In 2020, Bluefield Research estimated that utilities nationwide will spend more than $3 billion on wastewater pipe repairs and replacements, addressing 4,692 miles of wastewater pipeline. This value translates into more than $18 per wastewater customer, a cost projected to grow by an average of 5% annually.

State and local entities shoulder the majority of capital projects and O&M expenses, which were approximately $20 billion in 1993 and increased to $55 billion by 2017.   In 2019, 90% of the nation’s $104 billion O&M funding need was met, leaving an annual gap of $10.5 billion. If trends continue, the country will face a single-year O&M shortfall of $18 billion in 2039. These expenses contributed to the 24% rate increase reported from 2008 to 2016.

Public utilities are looking to recoup savings and generate profits by implementing innovative technologies that reuse water, recover energy, and recycle nutrients.  Of these three, thermal energy is the most plentiful and valuable. 

The value of wastewater thermal energy

Energy Embedded in Wastewater. Chemical - 20%, hydraulic less than 1%, thermal 80%. Source: Energy from Wastewater ENERG6C13-Factsheet
  • 80% of the energy embedded in wastewater is thermal, indicating that a significant portion of recoverable energy in wastewater is currently unexploited.
  • Compared with other traditional sources for heat pumps (groundwater, geothermal heat, or outdoor air), wastewater usually has a higher temperature and a relatively constant temperature, generally between 50ºF/10ºC and  77ºF/25ºC. 
  • Thermal energy could yield about 5.8 kWh/m3 for a drop of 41ºF/5ºC in wastewater temperature.
  • Buildings can be both heated and cooled using energy from wastewater
  • The heat from wastewater is CO2-free and represents a major opportunity for the energy transition in the heating market.
  • The heating market accounts for well over 50 % of the ultimate consumption of energy, even in a moderate climate
  • It has the potential to generate 851 trillion BTU of energy annually – enough to heat approximately 13 million homes, nearly the number of households in California