Be it eco-districts or district energy, the result is the same—independent power. In place for decades across the country, district energy is evolving. Eco-districts, a newly coined term, have priorities that often extend beyond energy. Both are being deployed to meet many challenges including building a smarter grid, increasing green power use and withstanding extreme weather, and both provide opportunities for the electrical contractor.
Sometimes the terms “eco-district” and “district energy” are synonymously used, but they can be different animals.
Eco-districts often focus on neighborhood sustainability that advances urban regeneration and community development. They scale up sustainability at a community level. A few examples are in Brooklyn, N.Y.; Denver; Portland, Ore.; and Seattle. San Francisco and Washington, D.C., are developing workable districts.
District energy has a specific infrastructure. The International District Energy Association (IDEA) describes it as a system delivering heating and cooling to several buildings within a downtown district, college or hospital campus, or even airports and military bases. This thermal energy is delivered through cogeneration, also known as combined heat and power (CHP). It can operate using waste heat from industrial processes, coal- or gas-fired boilers, and renewable energy such as geothermal, hydro, solar, biogas, municipal solid waste, or other types of biomass. IDEA estimates there are more than 700 district energy systems in the United States (at least one system per state), some dating back to the 1800s. The greatest number is located on university campuses, followed by healthcare properties and community utilities.
“District energy is similar to eco-districts as the benefits are relativity the same, including being more energy-efficient, water-efficient and economically productive,” said Carol Werner, executive director for the Environmental and Energy Study Institute (EESI) in Washington, D.C. “Eco-districts speak to the greater livability of the community overall. We’ve seen an explosion in interest and concern within community energy efforts to provide greater resilience and incorporate a variety of energy sources. Superstorm Sandy and Katrina before that changed the conversation. Ensuring reliable and reliant energy to keep central services online has become keenly important.”
Werner cited a number of power sources and tactics that can provide local power across the United States, including energy storage, demand response and distributed generation, tapping one or a collection of clean-power producers such as fuel cells, integrated wind and thermal, geothermal, bio fuels, and small-scale hydro. She feels ECs are well-positioned to play an active role in this renewed interest in independent power and should be attuned to district-power efforts in their region.
“Contractors are a vital part in the design and crafting of district solutions where it may not be business as usual in the use and delivery of power,” Werner said. “Those electrical contractors who know how to install and wire solar, work with integrated power systems, and optimize building operations are coveted.”
New out of old
Trent Berry, principal at Reshape Infrastructure Strategies Ltd., Vancouver, Canada, works with U.S. clients pursuing eco-districts and district power. He offered an interesting perspective.
“When it comes to power delivery in North America, we started out as energy districts with electric in tandem with a thermal network,” he said. “We changed as utility power to all was favored. The practice of heat recovery was lost as well. Fast-forward to today, and district energy is getting a second look. Drivers include a demand for cleaner energy and a lowering of greenhouse emissions. Maintaining reliable power is another need based on the precarious nature of big grid systems. Microgrids and power islands are emerging.”
Eco-districts and district energy can be found in urban areas or densely populated pockets.
“If you visualize different-sized bubbles based on density, an eco-district is the largest bubble,” Berry said. “But there’s a challenge. Districts require political planning and a clear conception, the required infrastructure, and may entail nonenergy-related considerations, such as reducing pollution from transportation or devising a water conservation plan. Maybe there is a formal retrofit program to deliver higher building performance. I deal more with the infrastructure side. That might include a mix of energy supplied by a microgrid and perhaps thermal. Maybe graywater usage, storm-water management or a local sewage treatment plant is incorporated.”
Green energy is a driver in today’s eco-districts but can vary in emphasis.
“I’m on the West Coast and observe an environmental emphasis for eco-districts,” Berry said. “One of my projects added biomass green power to California’s Stanford University’s stream energy grid. In contrast, the City of Berkeley is interested in resilience because of earthquakes. In New York City and state, resiliency and reliability of power have often become the primary need and interest because of recent storms.”
EcoDistricts is an advocacy organization formed three years ago by CEO Rob Bennett to promote neighborhood sustainability to give planners and others the tools to meet their objectives. The Portland, Ore.-based organization further defines self-sustaining districts as ones that embrace the so-called “triple bottom line” to achieve social, economic and ecological unanimity.
Joining LEED for Neighborhood Development, the Living Building Challenge and others, EcoDistricts introduced its own sustainability protocol in April 2016 to help committed communities achieve their goals. While eco-district activity is strong in Europe and Canada, Bennett wants to help stimulate activity here in the United States and sees ECs playing a part.
“Eco-districts need to turn to electrical contractors who can deliver high energy performance in buildings and across a neighborhood,” Bennett said. “Contractors can provide backup power, storage and other redundancies to create power reliability. They can work with nontraditional energy sources, and green building has created a lot momentum for energy efficiency now being translated for neighborhood-scale projects.”
Codes, standards and other governance are needed to further stimulate eco-districts and district energy. Customers also need to be on board with independently delivered energy.
“Certainly, there are tremendous opportunities for district energy within dense, mixed-load neighborhoods,” he said. “And though districts exist, they need a demonstrable franchise area, a local partner to require hook up to their systems. If thermal is the preferred choice, what does it look like? Planners need guidance. Also, property owners haven’t historically wondered who generates their power as long as it’s reliable and low-cost. Owners need to be engaged to move district power forward.”
A success story of note
District Energy St. Paul evolved while adhering to a triple-bottom-line philosophy and has its own eco-district within its territory. The community energy provider is highly regarded for its embrace of renewable energy and energy conservation measures that supply district heating and cooling, CHP, solar-thermal and thermal storage. It serves an estimated 800 customers representing commercial, residential multiunit, light industrial and other buildings within and outside St. Paul’s central business districts. Moving to eliminate coal (now less than 20 percent), biomass, natural gas and solar are the majority of its energy mix.
The evolution is noteworthy. Beginning in the early 1980s, St. Paul offered district heating to some 83 customers and added district cooling (using chilled water) 10 years later. In 2003, it became a green-energy service provider, constructing a CHP plant fueled by clean, urban wood residuals producing about 65 megawatts (MW) of thermal energy for district energy and 25 MW of electricity for utility Xcel Energy. It is the largest wood-fired plant serving a district energy system in the nation.
In 2011, a 23,000-square-foot solar-power system composed of 144 flat-plate collectors was added, resulting in one of the country’s largest hot-water solar projects and the first in the United States to be integrated into a district heating system. The system peaks over 1.2 MW and generates an estimated 1,000 megawatt-hours of heat each year.
“The renaissance in district energy is now,” said Ken Smith, president and CEO of Ever-Green Energy, St. Paul, Minn., which operates and manages District Energy St. Paul. “You are seeing growth in district energy because it’s a low-carbon delivery system, it taps wasted energy and uses CHP. Each feature has some electrical component, ranging from the mechanics of a plant delivering the thermal energy, to the controls and other infrastructure. We spend a lot of money using electrical contracting services. As the electricity system transitions to more integrated and distributed power including storage, wind, solar and microgrids, it’s going to take place in districts, communities and campuses. This relationship between thermal and electrical is joined. There are a lot of intersections.”
Smith sees opportunity for ECs even if a system is solely thermal; such systems demand powering sophisticated pump work. Markers are expanding for district energy, including data centers, an electricity-intensive power user. By capturing the heat generated with a heat or air exchanger into a thermal source (maybe water or glycol), you create a smart and efficient reuse rather than releasing the heat into the atmosphere.
“A lower carbon future and a smart flexible grid closer to the load makes the case for district energy as a more efficient, increasingly primary energy provider,” Smith said. “We are finding we can do more with it, too. For instance, you’re seeing the integration of storage. Thermal energy storage is a technology that allows excess thermal energy to be collected for later cooling or heat. We’re never done in progressing district energy.”
To learn more about eco-districts and district energy and to identify current and future activity, visit ecodistricts.org, districtenergy.org, sustainablecommunities.gov, eesi.org and the Urban Directors Sustainability Network at usdn.org.