NYC’s Water-Energy-Carbon Nexus

NYC’s Water-Energy-Carbon Nexus

The Paris Climate Agreement commits nations to limit global temperature rise to well below 2 degrees Celsius and to aspire to limit global temperature rise to 1.5 degrees Celsius. In support, New York City’s Mayor has committed the city to limiting global temperature rise to 1.5 degrees Celsius. 

*By Robert C. Brears

New York City faces a variety of climate change-related threats including rising sea level, increased flooding, and more frequent and intense storms. Mid-century, the city will also experience warmer, hotter days with average temperatures projected to rise by 3.7 degrees Celsius. By limiting temperature rise to 1.5 degrees Celsius it means residents will be able to breathe cleaner air, live in more comfortable surroundings, and live in a city that is more resilient to climatic extremes.

Water-Energy Nexus Tool

One tool the city has at its disposal to reduce greenhouse gas (GHG) emissions is the Department of Environmental Protection’s (DEP) Water-Energy Nexus Tool. Operation and maintenance of the city’s water supply, stormwater, and wastewater management facilities currently account for 18% of total New York City government emissions. To reduce its carbon footprint, DEP has been tracking and identifying opportunities to offset GHG emissions and/or optimize indirect energy co-benefits.

New York City aiming for low-carbon future

New York City aiming for a low-carbon future

The water-energy-carbon nexus

The Water-Energy Nexus Tool quantifies the impact of the city’s watershed protection, green infrastructure, water demand management and conservation, and wetland restoration programs on DEP’s overall energy and GHG portfolio. By analyzing these initiatives through the Water-Energy Nexus tool it helps determine which program can provide the largest energy and GHG reductions at the sewershed-level.

Energy saved and carbon sequestered

The tool can analyze energy saved due to less demand on water supply and wastewater treatment systems from reductions in water consumption, leak detection and repair, and fixture replacement programs. The tool can also analyze the decrease in energy requirements for maintaining and operating the wastewater treatment system from installations of rain gardens, green roofs, and other strategies to capture stormwater before it enters the sewer system. Finally, the tool can calculate the benefits of carbon sequestration for the added vegetation from green infrastructure and wetland restoration programs.

The take-out

Energy usage and GHG emission reductions can be achieved by reducing the volume of water and wastewater requiring treatment.

*Robert C. Brears is the author of  Urban Water Security  (Wiley),  The Green Economy and the Water-Energy-Food Nexus  (Palgrave Macmillan), and of the forthcoming title  Blue and Green Cities  (Palgrave Macmillan). He is Founder of Mitidaption, which consults on climate change risks to business, governance, and society.

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