Thermal energy networks are emerging as a sustainable solution to help decarbonize neighborhoods in the United States. These systems, which employ networks of underground pipes to transport steam or water among nearby buildings, have traditionally been used for heating and cooling institutional campuses, military bases, and densely built urban environments worldwide. However, a new generation of thermal energy networks, focused on low-carbon solutions, is making inroads in various U.S. cities, thanks in part to significant support from the U.S. Department of Energy (DOE).
Overview of Thermal Energy Networks
District Energy Systems
Historically, district energy systems have relied on central cogeneration plants that burn fossil fuels or biomass to generate heat. These systems leverage the proximity of buildings within a network to efficiently distribute thermal energy. The traditional approach has been effective in densely populated areas, providing a reliable source of heating and cooling.
However, the reliance on fossil fuels has raised concerns about emissions and sustainability. As a result, there is a growing interest in transitioning to low-carbon alternatives that can provide the same benefits without the environmental drawbacks. This shift is driving innovation in the design and implementation of thermal energy networks.
Advancements in Thermal Energy Networks
The new wave of thermal energy networks in the U.S. seeks to break away from combustion-based systems by employing low-carbon sources of heat energy, such as municipal wastewater, geothermal energy, and other renewables. These advancements are not only reducing emissions but also improving the efficiency and reliability of heating and cooling systems.
One of the key innovations is the use of geothermal energy, which harnesses the stable temperatures found underground to provide consistent heating and cooling. This approach is being tested in various pilot projects across the country, demonstrating its potential to replace traditional fossil fuel-based systems.
DOE Initiatives and Support
Funding and Design Proposals
In an effort to spearhead the next generation of thermal energy solutions, the DOE awarded $13 million to 11 communities in 2022 to design community-scale thermal energy networks. The goal of these projects is to harness heat energy from non-combustion sources, providing a cleaner and more sustainable alternative to traditional heating methods.
A notable example is a project in Framingham, Massachusetts, which aims to connect to a networked geothermal system that has been operating since June, serving municipal buildings, small businesses, and residential homes. This project highlights the potential for geothermal energy to be integrated into existing urban infrastructure, providing a scalable solution for other communities.
Potential and Benefits
Proponents highlight the potential of thermal energy networks to serve as a safer and more efficient alternative to traditional utility gas services. These systems could significantly reduce local air pollution and greenhouse gas emissions, contributing to broader efforts to combat climate change.
Thermal energy networks use electricity to move heat, rendering on-site fossil fuel combustion unnecessary. They are notably more efficient than traditional heating methods, such as electric baseboard heating and air-source heat pumps. This efficiency translates into cost savings for consumers and reduced strain on the electrical grid.
Diverse Heat Sources
Ground and Surface Water
Thermal energy networks can draw from various heat sources, including the ground, surface water, and waste heat from municipal wastewater. For example, Toronto’s district cooling network utilizes the cold depths of Lake Ontario, providing a renewable and reliable source of cooling for the city’s buildings.
Similarly, a project in Duluth, Minnesota, plans to use wastewater effluent as the heat source for a network serving commercial and residential buildings. This innovative approach not only reduces emissions but also repurposes waste heat that would otherwise be lost, enhancing the overall efficiency of the system.
Hybrid Heat Sources
Some designs, such as the one proposed in Carbondale, Colorado, use a hybrid approach, supplementing ground-source loops with gas-powered boilers and solar thermal systems to meet peak demand. This approach reduces the size and cost of geothermal systems, making them more accessible for smaller communities and individual buildings.
By combining multiple heat sources, these hybrid systems can provide a reliable and flexible solution that adapts to varying energy demands. This versatility is crucial for ensuring the widespread adoption of thermal energy networks, particularly in regions with diverse climate conditions.
Technological and Logistical Challenges
Customization and Education
One significant challenge is designing systems that are both replicable and customizable to specific sites. Proponents also need to educate customers, city planners, and stakeholders about the benefits and scope of these networks. This education is essential for gaining public support and ensuring the successful implementation of projects.
Customization involves tailoring the design of thermal energy networks to the unique characteristics of each site, including the local climate, building density, and available heat sources. This process requires careful planning and collaboration between engineers, architects, and city officials.
Financial and Health Benefits
According to the Applied Economics Clinic, homes using networked geothermal systems in Massachusetts spend significantly less on heating annually compared to homes using gas furnaces. These cost savings can make a significant difference for households, particularly in regions with high energy costs.
By eliminating on-site fossil fuel combustion, thermal energy networks can alleviate environmental burdens in communities that traditionally suffer from high levels of air pollution. This improvement in air quality can reduce rates of asthma, cancer, and heart disease in these areas.
Building Support and Collaboration
Utility Involvement
Growing public awareness of the health benefits of decarbonization is crucial for driving the deployment of thermal energy networks on a large scale. Some utilities are already supporting these efforts. For example, Eversource has rebranded its gas sales team to focus on “customer thermal solutions,” reflecting a shift towards geothermal projects.
This involvement from utilities not only helps in promoting thermal energy networks but also in providing technical and financial support for their deployment. Utilities have the resources and expertise to implement these projects efficiently, ensuring that they are accessible and beneficial to customers.
City Government Roles
City governments can enhance the viability of thermal energy networks by collaborating with other successful projects. Examples include Yale University’s planned geothermal system and the Meriden Housing Authority’s deployed network in Connecticut. Engaging closely with project developers, including utilities like Eversource, can ease the burden on city employees during construction and ensure community support.
City governments play a crucial role in facilitating the development of thermal energy networks by coordinating with stakeholders, securing funding, and promoting public awareness. Their involvement is essential for overcoming regulatory and logistical barriers that can impede the progress of these innovative projects.
Future Prospects
DOE Pathways to Commercial Liftoff
The DOE plans to release a report by the end of the year outlining pathways to commercialize utility- and community-scale geothermal networks. This report aims to showcase the scalability and adaptability of these systems to different geographies and community needs. The report will provide guidelines and best practices for deploying thermal energy networks, helping communities across the country to leverage this technology for sustainable heating and cooling solutions.
With increasing support from the DOE and successful pilot projects in various cities, these networks have the potential to become a mainstream solution for reducing emissions and improving air quality. The future of urban energy could very well be rooted in the ground beneath our feet, providing a cleaner and more sustainable way to heat and cool our communities.
Next Steps
Thermal energy networks are gaining traction as a sustainable way to decarbonize neighborhoods across the United States. These systems use networks of underground pipes to transfer steam or water between nearby buildings, serving functions like heating and cooling. Traditionally, such networks have been deployed in institutional campuses, military bases, and densely populated urban settings globally.
However, a new generation of thermal energy networks focusing on low-carbon technologies is spreading to various U.S. cities. Much of this progress is supported by significant backing from the U.S. Department of Energy (DOE). The objective is to reduce carbon emissions and promote cleaner, more efficient energy use in urban environments. This emerging technology represents a pivotal step toward achieving nationwide sustainability goals.
By adopting these advanced thermal systems, cities can harness renewable energy sources more effectively, reducing reliance on fossil fuels and curbing greenhouse gas emissions. These networks not only provide a reliable and efficient way to manage energy for heating and cooling but also play a crucial role in the broader effort to combat climate change. As part of the ongoing drive to create greener cities, thermal energy networks stand out as a viable and innovative component of the clean energy landscape.
