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Berkeley Lab outlines options for Block Island energy future, finds large solar potential but key constraints
Summary
A Berkeley Lab team presented a 2040 roadmap for Block Island showing roughly 736 acres of potentially viable land (about 43 MW) for community solar, sizable rooftop potential and a steep set of trade-offs driven by the island—s undersea cable, seasonal demand swings and storage costs.
Pete Kaspers, a lead scientist on the Berkeley Lab Energy Transition Initiative Partnership (ETIP) project, told the Block Island Utility District on Monday that the island has technical space for large-scale community solar but faces integration and resilience trade-offs.
"The undersea cable ... maximum carrying capacity is 30 megawatts," Kaspers said, noting that is "way more demand than you all need" compared with the island—s recent one-hour peak demand of about 5.4—5.7 megawatts and a low-season minimum near 0.7 megawatts. That capacity, he said, cannot be back-fed: any power generated on-island must be consumed locally, stored or curtailed.
Kaspers described a parcel-level GIS screen that excluded wetlands, buffers, building footprints, slope and other constraints to identify what he called an "upper bound" of about 736 acres that could support ground-mounted community solar — a conversion the team estimated at roughly 43 megawatts of capacity. He emphasized that the number is an upper-bound technical estimate, not a siting directive: "You obviously are not gonna develop all this because you don't need it," he said.
On distributed rooftop systems, the team sampled about 25 houses with the National Renewable Energy Laboratory—s PVWatts tool and estimated an average future system of about 5.1 kilowatts. Under the study—s simplifying assumptions, that implies roughly 9.4—9.5 megawatts of additional rooftop capacity is technically possible, though the utility enforces an export/capacity cap that limits how much can interconnect without further upgrades.
Kaspers also presented demand-side scenarios through 2040. Under an aggressive "established goals" case aligned to state decarbonization targets, winter peaks could rise substantially because of building electrification (air-source heat pumps) and electric vehicles, potentially multiplying peak capacity needs and requiring major infrastructure changes.
Jeff, a Block Island utility representative, acknowledged the trade-offs and flagged future cable responsibilities: "I can tell you what our portion is right now, and it's about $3,500 a month," he said, describing the island's current monthly O&M share for the cable. Board members and residents urged the project team to include lifecycle O&M and replacement costs in scenario comparisons.
Kaspers recommended including batteries or other storage in scenarios where significant on-island generation is pursued, saying that without storage the island would at times have to curtail production. "You can store it. ... Or it has to be shut off and wasted," he said, listing the three practical outcomes for locally produced energy.
The Berkeley Lab team proposed six 2040 scenarios that trade off reliability, affordability, sustainability and equity — from a fully self-reliant island to low-cost, off-island renewable purchases with targeted local programs — and said the final roadmap will provide stakeholders an interactive model to compare those options.
Kaspers said he will return in the spring with refined results and an Excel model stakeholders can use to test combinations of community solar, storage, program design and off-island power purchases.
