University and college campuses are places where young minds are shaped, and groundbreaking research is conducted. Cities are often the places where recent graduates gather to put those ideas learned in the classroom into action. Both are also sources of innovation for the technology that is literally powering the work being done on campus and in office buildings. Business districts and campuses often rely on combined heat and power (CHP) district energy systems, also referred to as cogeneration, to provide heat and electricity to academic, research, office, and residential spaces.
Unlike a typical power plant that exhausts surplus heat to the local environment after generating power, a CHP system recovers heat to produce additional electricity, drive pumps and compressors, and supply space heating and hot water to buildings on the district energy piping network, essentially doubling the fuel efficiency of the system. CHP systems are able to convert up to 75% or more of fuel input into usable energy, compared to a traditional power plant typically operating at 35% to 40% efficiency. Even more importantly, having a fuel flexible source of nearby power, configured as a microgrid, can dramatically enhance reliability and resiliency for the local economy.
Staying Flexible, Adaptable, and Reliable
As higher education institutions, utilities, and cities around the world look to meet net-zero goals, they must also maintain reliable and resilient energy for their communities. Because of its flexibility and adaptability, district energy is a versatile way to decarbonize and deliver heating and cooling to communities, clusters, and cities. These systems are often deployed in dense urban central business districts, healthcare and research campuses, airports, and military bases, where there is a cluster of buildings, or a district, where nearby buildings can be connected through a network of underground pipes to a thermal energy source. District energy systems work in arctic, sub-zero settings, as well as in sweltering, humid locations like the Middle East.
Along with flexibility, these systems also have another strength—their ability to adapt and deliver renewable or cleaner energy at scale. Dozens, or even hundreds, of buildings can be connected to the central plant in a city or on a college campus. By aggregating the thermal energy needs of multiple buildings, economies of scale enable integration of renewable or low-carbon resources at the central plant, delivering the lower-carbon thermal energy downstream to the connected community. For example, surplus or waste heat can be recovered from a nearby sewer or wastewater line, an industrial facility, or data center, and integrated into the supply mix. This may not be technically or economically feasible on a building-by-building stand-alone basis.
The First Environmental Solution for Cities
When initially introduced about 140 years ago in cities like New York, Boston, Cleveland, and Philadelphia, district energy was often a primary environmental strategy to improve urban air quality and reduce the risk of fires. Among the first power generating stations in cities, CHP facilities not only produced local power near the users, but were able to provide steam to dozens or hundreds of buildings, eliminating hundreds of individual building boilers, cutting pollutants, and reducing harmful particulates in the air. By turning to district energy, cities were able to aggregate to cleaner, safer, and more efficient infrastructure. Now, similar air quality objectives are motivating community leaders in countries like China, Chile, and other emerging economies seeking to make the shift to cleaner solutions for public health along with economic development objectives.
Today, here in North America, those same district energy facilities that were built downtown to supply local power are often still connected to the regional power grid at a wholesale level. Downtown district energy providers in cities are evaluating and implementing electrification at scale through investments in large industrial heat pumps, electric to steam or hot water boilers, and leveraging access to renewable energy supplies. Technologies are readily available to convert renewable power to high-temperature heat or steam, enabling hundreds of connected customer buildings to leverage grid-scale renewable power and reducing disruption and heating, ventilation, and air conditioning (HVAC) transition risks at the building level. Moreover, buildings avoid the challenges of managing cost exposure to retail power volatility, which can be exacerbated during periods of extreme temperatures or grid constraints.
Weathering the Storm with District Energy
Extreme weather events are happening with greater frequency and ferocity. College and university utility systems must be able to withstand supply curtailments or grid interruptions from extreme heat and cold, and still protect people as well as assets such as precious medical research. In addition to actively cutting carbon emissions, campus energy professionals have a duty to design, operate, and maintain highly reliable energy services for their communities. During named storms, like Sandy, Harvey, or Uri, the district energy microgrid systems at Princeton University, New York University, the University of Texas, Austin, and Texas Medical Center all maintained operations supplying critical power, heating, and cooling to ensure the safety of the local population and continuity of the local economy.
Pittsburgh’s Microgrid Takes Off. In Pittsburgh, a first-of-its-kind microgrid is maximizing resilience, reliability, and sustainability at Pittsburgh International Airport. The microgrid will allow the airport to operate in conjunction with, and as needed, independent of the electric grid, with power generated through five natural gas–fueled generators and nearly 10,000 solar panels spread across eight acres of land—giving the airport a source of sustainable, renewable energy to integrate with the natural gas sourced from underground on the airport property. With the microgrid, the airport is able to provide more resilient and reliable power—keeping flights on schedule and avoiding the ripple effect of delays that may otherwise impact travelers.
Negawatts and Megawatts—Chicago’s Carbon-Free District Cooling System. As much as cities and campuses appreciate the importance of producing local power, much can also be said for avoiding or shifting huge swaths of power demand through the scale of large district cooling networks. Central district cooling plants produce chilled water that is circulated through underground supply and return piping networks, allowing customers to avoid peak demands caused by air conditioning equipment while reclaiming valuable building space for electrical vaults, chiller rooms, and high-value rooftops for other tenant uses or amenities. In Chicago, for instance, the district cooling system produces more than four million pounds of ice overnight that is stored in five interconnected district cooling plants, discharged during daytime hours for customer cooling, and shifting more than 10 MW of peak power demand off the local distribution grid. Moreover, the electric-driven chiller plants have contracted for carbon-free power and are harvesting ultra-filtered Chicago River water for condenser cooling and seasonal free-cooling, reducing use of potable city water by more than 250 million gallons per year.
A Sustainable Solution for Our Net-Zero Future
The energy transition is well underway and, in many cases, is following the path of local food and farm-to-table, where resources that are available nearby often represent a more efficient and sustainable model. Power, heat, and cooling are being re-integrated at scale, especially in cities and campuses, to reduce waste, optimize reliability and resilience, and accelerate the shift to a lower-carbon economy. District energy systems are a valuable and viable solution that are gaining ground and helping cities, communities, and campuses to mitigate and mobilize more effective climate adaptation.