Efficiency at the Energy-Water Nexus Offers Savings for Utilities

Efficiency at the Energy-Water Nexus Offers Savings for Utilities

The need for collaborative energy and water efficiency efforts has been recognized for at least the past couple decades, but is more important now than ever. The energy-water nexus, where energy and water needs intersect, can be a beneficial area for utilities to focus on, as it contributes to overall environmental health and savings for both water and energy utilities.

Water and energy systems are intricately connected and mutually dependent on one another. Water utilities need energy in order to carry out almost every essential task, be it extracting and delivering water to their customers or treating wastewater. On the flipside, water is necessary for almost all phases of energy production and the generation of electricity.

Water and wastewater utilities could find significant energy savings by implementing efficiency practices. The American Council for an Energy-Efficient Economy (ACEEE) released a useful report in November quantifying what these savings could look like for those that implement efficient practices at the energy-water nexus.

Water sector could save kWh by the millions

Many of their numbers are dated (a portion of the data ACEEE drew on was gathered as far back as 2002), but some data is more recent, and the numbers are still a reasonable benchmark to work from. The ACEEE report included the average energy intensity for water and wastewater utilities in kilowatt hours per million gallons (kWh/MG) for systems of various sizes to give facilities an idea of just how much electricity goes into water service (all numbers are from the ACEEE report):

• 1,621 kWh/MG for large utilities (with more than 15,000 service connections)
• 1,560 kWh/MG for medium utilities (5,000 – 15,000 service connections)
• 2,912 kWh/MG for small utilities (fewer than 5,000 service connections)

The smaller the utility, the more electricity is needed per unit of water, which translates to higher water production costs. However, all utilities, regardless of size, stand to benefit from the energy savings resulting from water efficiency measures. The ACEEE found that 313 million kWh could be saved with a 5% reduction in water supply and treatment leaks. Most significantly, 41 billion kWh could be saved if indoor residential hot water use was reduced by 20%. If we estimate the price of electricity to be roughly 7 cents per kWh (a very conservative estimate), these measures add up to $21.9 million from reducing leaks and $2.8 billion from residential hot water reduction that could be saved nationwide.

Efficiency practices pay for themselves

Sourcing, conveying, and treating water are energy intensive activities, and though many are concerned about the cost of making these processes more efficient, there are certainly cost-effective strategies for doing so. For instance, the cities of Lowell and Lawrence, MA were able to create revenue by replacing aging water meters with newer, high accuracy meters. This action alone amounted to approximately $500,000 for Lowell and $1.3 million for Lawrence in additional annual income. Both cities also installed solar photovoltaic panels on their water treatment facilities, which created yet another revenue source in the sale of Solar Renewable Energy Credits while also offsetting the cost of energy used at the facilities. Each city anticipates the resulting savings and revenue will amount to over $100,000 annually.

Additionally, aeration is a huge electricity user at wastewater treatment plants. Though aeration system upgrades might be expensive, many states and local agencies offer funding options like loans, rebate programs, and grants that will defray some of the upfront costs. And the long-term savings can pay for the costs in relatively short order.

Ultimately, for many utilities, any upfront cost for improvements at the energy-water nexus will be quickly paid off with the energy savings from a more efficient system. Whether funding is available for large upgrades or not, water conservation efforts large or small will pay for themselves, making them a savings opportunity most utilities cannot afford to miss.

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