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A New Decarbonization Strategy Rises from the Streets of New York City: How Con Edison’s District Steam System is Planning for a Carbon-free Future

By District Energy posted 11-15-2023 17:20


If you’ve ever watched an old movie set in New York City and seen steam rising from the street at night or out of the subway system while a private detective slinks through the streets trying to solve the crime, or you’ve been a tourist in the city that never sleeps and walked by one of those orange and white tubes with steam billowing out the top, then you are familiar with New York’s iconic district steam system, even if you may not have realized it.

The district energy system in New York City is in a unique position. Unlike many of IDEA’s members, its system is not only comprised of a massive network of plants and pipes that provides reliable and efficient heating to hundreds  buildings, but it is also a part of one of the country’s largest utilities – The Consolidated Edison Company of New York. Con Edison, as it’s known, is a provider of electric and gas services, as well as steam. The company relies on steam as part of an integrated energy system that strengthens New York City’s energy resiliency – helping to reduce demand and strain on the electric grid and providing a lower-carbon alternative to on-site fossil gas or oil. The Con Edison team will continue to work with existing gas/oil customers so they can understand their energy options as well as available incentives associated with potential conversions.

Con Edison’s district energy system itself is also unique. It’s the largest steam system in North America, with 105 miles of pipes running from Battery Park in the southern tip of Manhattan, all the way to 96th street, serving 3 million people and more than 1,500 buildings along the way. The system also provides heating and cooling to some of New York’s most iconic landmarks, including the Empire State Building, the Chrysler Building, Grand Central Terminal, the United Nations building, Rockefeller Center and the Museum of Modern Art – where it helps keep some of the world’s most famous paintings at precisely the right temperature and humidity levels.

Now, the venerable system that started providing steam to buildings in the city in 1882 faces a new challenge as well as an opportunity – to decarbonize. As the recent flash floods in Brooklyn illustrate, climate change-driven extreme weather events are very real and potentially devastating to the daily lives, health and livelihoods of people in New York, as elsewhere around the world.

Due to the effects of climate change, customer demand and regulations such as Local Law 97, Con Edison’s goal is to be net-zero by 2050, and the steam system will play a large role in those plans. To reach that goal, the company has identified several decarbonization technologies in its long-range plan that it proposes to employ throughout the system over the next decades. 

The technologies are:

·         Industrial heat pumps

o   Once implemented, these would be some of the largest heat pumps in the world, and among some of the first to use river water for heating rather than cooling. Using water from both the East and Hudson Rivers, the heat pumps would essentially take BTUs (British Thermal Units – a measure of the heat content of fuels or energy sources) out of the river water (as well as other waste heat sources potentially) and funnel them into the steam system. This process would also cool the rivers, which is beneficial for the fish and the river ecosystem.

·         Low carbon fuels

o   These fuels would include renewable natural gas and potentially hydrogen. Con Edison is working with New York City to procure anaerobic digester plants, and is also working with the New York State Energy Research and Development Authority (NYSERDA) to determine the most effective processes for green hydrogen production and delivery.

·         Thermal energy storage

o   Another option Con Edison is exploring is thermal energy storage. While a number of IDEA’s members use ice and chilled water thermal storage in district cooling systems, Con Edison would employ thermal storage for heat, through the use of hot rocks that heat up bricks, molten salt and sand batteries.  Thermal storage extends the utility and functionality of renewable resources by enabling district energy systems to store intermittent supplies for periods of higher demand. This technology will also reduce the need for additional production assets to meet the limited peak load hours of the system.

·         Electric boilers

o   This is an electric technology that generates steam without fuel combustion. They can also be paired with energy storage to optimize their renewable benefits. Electric boilers essentially transform dedicated steam plants into net-zero greenhouse gas emission generators. However, these are very electricity-intensive, and will be feasible  if more renewable sources such as off-shore wind come online and connect with the grid.

·         Carbon capture

o   Technology that absorbs carbon from point-sources (such as steam boilers), or directly from the air, to offset carbon emissions from other activities, reducing greenhouse gas emissions and supporting larger net-zero goals. The main challenge with carbon capture is figuring out what to do with the carbon once it is captured, and Con Edison is currently exploring several different solutions.

Each of these  technologies will likely have to be used in conjunction with the others.  There is no single solution to transitioning the way we heat and cool our buildings a carbon-free future.  Especially in a dense energy environment of cities, it will involve a mix of technologies and renewable sources to deliver lower-carbon energy services at scale with an emphasis on reliability and resilience.