MMWEC Uses DEED Grant To Develop Model To Undergrounding Cost-Benefits

July 28, 2022

by APPA News
July 28, 2022

The Massachusetts Municipal Wholesale Electric Company (MMWEC) has completed an in-depth study of the costs and benefits of the combined undergrounding electric and broadband internet lines in metropolitan areas with a grant from American Public Power Association’s Demonstration of Energy & Efficiency Developments (DEED) program.

MMWEC’s research team used the grant to build a model that optimizes construction of new utility corridors based on estimated cost and projected benefits, including enhanced reliability of electric service and access to broadband.

MMWEC’s researchers conducted a literature review to collect background information on electricity and broadband cost elements. They also collected data on undergrounding from public and commercial sources, including member utilities such as Shrewsbury Electric and Cable Operations and Concord’s public power utility, as well as the 2020 Underground Distribution Systems Reference Book (Bronze Book) from the Electric Power Research Institute and real estate data from Zillow that was used to assess aesthetic benefits from undergrounding in the form of increased property values.

The researchers analyzed the co-deployment of electric and broadband lines to develop data-driven cost and benefit models. “Our synthetic and disaggregated approach is readily deployable to other similar study areas and provides effective decision-making capabilities with limited amounts of data,” the MMWEC researchers said in their report.

MMWEC also took into consideration costs beyond the plainly financial, such as environmental damage caused by undergrounding from soil erosion and the disruption of ecologically sensitive habitats, as well as safety hazard for crews attempting to locate and repair failed equipment that has been undergrounded.

In their preliminary analysis, the MMWEC researchers found that the per-mile cost of underground installation is a major cost driver. The lifespan expected from underground cable is also a key cost factor, and they found that commonly assumed lifespan values may be significantly underestimated.

“Undergrounding electric and broadband cables is a viable approach for improving resilience,” MMWEC said in its final DEED report, noting, however, that there are many variables that have to be taken into consideration. “The massive investment costs [of undergrounding] require frameworks to analyze costs and benefits of competing strategies. Prior efforts have been too generalized and not accounted for broadband.

Thus, we present a framework that demonstrates a localized approach, using Shrewsbury, MA, as a case study.”

The researchers also found that aggressive conversion strategies, that is, those that convert to underground from overheard well before the lifespan of the overhead cable is reached, lead to greater aesthetic benefits, yield higher avoided economic losses, and, in the Shrewsbury case study, netted benefits totaling over half $500 million.

On the other hand, the researchers said, moderate conversion strategies exhibited benefits toward the end of the simulation. Optimal potential benefits can be achieved by undergrounding after the complete lifespan of the overhead lines has been reached, they said.

Looking forward, MMWEC said it plans to publish a paper with the detailed models and results of its research and another paper that will use a Monte Carlo simulation to analyze competing strategies. “This will also allow us to improve the generalizability of the model by incorporating additional factors critical to the estimation process,” such as segment length and type and the effect of a variety of conditions on the network’s sustainability and resilience, MMWEC said.

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