Study Finds Water Reuse Could Help Lower Carbon Footprint

“Carbon footprint” is a relatively new term – at least to me – and recently I’ve begun hearing discussions about the carbon footprint of the water industry in general and individual pieces of equipment in particular.

by James Laughlin, Editor

“Carbon footprint” is a relatively new term – at least to me – and recently I’ve begun hearing discussions about the carbon footprint of the water industry in general and individual pieces of equipment in particular.

Pumps and aeration systems have the big shoes in the water industry, but certainly utility fleet vehicles, lighting systems, air conditioning and everything else that makes up a water system contribute to a utility’s carbon footprint.

Carbon footprint is a measure of the impact human activities have on the environment in terms of the amount of green house gases produced, measured in units of carbon dioxide.

Greenhouse gases typically are linked to energy consumption and tied to the production of CO2. However, the methane and N20 generated by traditional wastewater treatment process also contribute to global warming and the greenhouse effect. A significant amount of research has already begun to lower greenhouse gas emissions from wastewater plants, and utilities are working to lower energy consumption – although at most utilities rising fuel costs are a bigger driver than concerns about the environment.

One interesting concept I encountered recently was the idea of water reuse and recycling as a means of reducing a utility’s carbon footprint.

The California Sustainability Alliance has released a new study entitled, “The Role of Recycled Water in Energy Efficiency and Greenhouse Gas Reduction.” The study estimates the potential energy and carbon benefits of accelerating and increasing the development and use of recycled water in the state of California.

Southern California wants to add more than one million acre-feet of additional water per year to replace imported and other water supplies that are no longer available. The study found that more than half of the water shortfall could be met by existing supplies of highly treated wastewater that is currently discharged to streams and the ocean.

According to the study, the long-term incremental water supply required to meet California’s needs is expected to come from seawater desalination projects. While desal can provide a drought-resistant and reliable supply, it can be energy intensive. The study concludes that using secondary and tertiary recycled water could save enough energy to power 150,000 homes.

“The energy savings from currently available recyclable water exceeds 15 percent of California’s total annual energy efficiency goal,” according to Laurie Park, Associate Director with Navigant Consulting and principal author of the study. “Equally important, this energy savings would reduce annual carbon emissions in California by half a million metric tons annually.”

The study recommends creating combined incentives that recognize both the water and energy benefits of recycled water as a way to offset the cost of creating and maintaining separate recycled water pipes and plumbing systems. The study contains additional findings on the cost of recycled water, measures that can be taken to accelerate its use, and the benefits of accelerated implementation.

To download a copy of The Role of Recycled Water in Energy Efficiency and Greenhouse Gas Reduction, go to the California Sustainability Alliance’s website: www.sustainca.org.

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