Cohoes Innovates with Municipally Owned Floating Solar Inspired by NREL Report

No U.S. cities have done anything like what Cohoes, N.Y. was proposing: a floating solar installation owned and operated by the municipality – but there was no reason it would not work. Two city employees of Cohoes, N.Y. were brainstorming how to power the city’s municipal buildings with renewable energy, but few options made sense. Cohoes has no rooftop solar and does not have acres of land that could be used for solar panels. Cohoes’ 17,000 residents were not rich due to their high level of low- or moderate-income (LMI). The solution had to be something local – something to keep cost savings within the community.

“We looked at every aspect of how to add clean energy to our working-class community,” says Theresa Bourgeois, director of operations for the city of Cohoes. “Then my colleague came upon the idea of floating solar. We considered our 10-acre water reservoir and asked, ‘Can we really utilize this?’ The more we researched, we realized yes, we can! In fact, it’s the best possible answer.”

Bourgeois and City Planner Joe Seman-Graves did their research and learned that the technology of floating solar is sound and that their reservoir could hold enough panels to power all Cohoes-owned buildings and streetlights – erasing around $500,000 in annual electricity costs – with 40% of the generated electricity remaining for civic use. Cohoes was able to complete the project with no problems, but it came at a high cost of $6million. This meant that they needed support from others.

Because municipalities are not eligible for the same tax incentives that private companies, they face a challenge in attracting clean energy investments. Instead, the city would need state, federal, and foundation funding. This is what they did in a 2018 National Renewable Energy Laboratory Report (NREL).

The NREL report that Bourgeois discovered was “Floating Photovoltaic Systems: Assessing the Technical Potential of Photovoltaic Systems on Man-Made Water Bodies in the Continental United States.” It provides coarse yet comprehensive data about potential U.S. “floatovoltaic” sites, including each reservoir’s estimated size, proximity to electric transmission, ownership status and current use. For Bourgeois and Seman-Graves, NREL’s data set was the missing link.

“NREL’s study gave us confidence and credibility in the power of this idea, that we could generate clean energy in Cohoes,” Bourgeois says. “We used the basic results in that study to provide information to Congress, to our representatives, to the public, showing that we have a viable option. It really drove our success in building support for the project.”

The report describes floatovoltaics, as a huge opportunity for renewable energy. NREL discovered that floating solar could produce almost 10% of the nation’s electricity if only a portion of the best reservoirs was covered. This includes nearly 250,000 human-made water bodies that aren’t used for recreation, tailings from mines, or fish and wildlife.

The report was valuable when Cohoes ran the idea by New York state agency representatives. Bourgeois and Seman-Graves referenced the number of possible reservoirs that could support floating solar – 492 in New York – to substantiate that not only are floatovoltaics viable, but that Cohoes could be at the forefront of a replicable model worth pursuing and funding. Cohoes was impressed enough to support it.

Similar success was achieved by Cohoes when the idea was run by elected officials. NREL’s data identifies a value proposition for renewable energy that appealed to state and federal representatives alike, with the latter advocating to fund about 50% or more of project costs.

NREL also found that many of the suitable reservoirs are in water-stressed areas with expensive land and electricity – these areas could find a shortcut to solar power with floatovoltaics. But for Cohoes, one statistic was missing in the data: What about floating solar’s proximity to low-income communities? Is this a feasible option? How many other communities could use the technology to generate clean energy in their own down-the–road reservoir?

As the Cohoes Municipal Floating Solar Demonstration project becomes a model for municipal ownership and small-city sustainability, the city is using NREL’s data to share resources, educate and advocate for environmental justice in related clean energy projects around the state, region, and country.

While pitching the project, Bourgeois wondered whether NREL’s data could be even more impactful; a visualization that breaks the data into congressional districts and economic factors might sum all 7,000 words up in a few seconds to show the economic imperative for Cohoes. Bourgeois connected with NREL and learned that no such visuals were planned, but the authors would happily provide input; so, Bourgeois teamed with nearby Rensselaer Polytechnic Institute, sending NREL’s paper to Rensselaer’s Institute for Data Exploration and Applications (IDEA) where students and faculty engage with data of imminent societal importance.

John Erickson (director of research operations at IDEA), was informed about the request. He enjoys visualizing economic and technical data. His first goal was to visualize NREL’s data overlaid with LMI maps. Bourgeois, Seman-Graves and he created the Floating Solar Explorer. The online exploration tool has a map of all the available reservoirs as identified by NREL. Additionally, it includes LMI information layered on New York from congressional districts. Erickson initially funded the data explorer as a way to share it with Cohoes project stakeholders. However, it is now a good option for undergraduate electives.

“We try to have our students be driven by questions from elsewhere. NREL’s floating solar data set is an excellent launching point for students to use data to explore topics of deep importance,” Erickson mentions.

Bourgeois & Seman-Graves have already created an exploration tool that is an example of cross-community collaboration. They plan for NREL’s data and accompanying visualization to be part of a wider virtual platform where the city can share and access information about the floating solar installation and where Cohoes can be a resource for K–12 education, university-based research, workforce development, and economic collaboration, all of which provide a roadmap for others to adopt community ownership.

In 2021, NREL started cost benchmarking floating PV system costs to determine their cost-competitiveness across the country. Another recent publication analyzed the benefits of pairing hydropower and floating PV systems around the world—a hybrid energy opportunity that could also be surprisingly cost friendly.

Read the complete story and report.