The recent news reports concerning the trial use of second-generation biodiesel for the June through August runs of the Island Home is a small but encouraging step for the Steamship Authority. The use of hydrotreated vegetable oil (HVO diesel or RD99) will indeed reduce greenhouse gas emissions, but some of the claims in the various news articles could in fact confuse the issues for the general public.

The claims regarding greenhouse gas emission reductions are true but potentially misleading. The quoted 60 to 90 per cent reductions in CO2 emissions refer to the complete fuel cycle from feedstock through refining and finally combustion. This measure is of global importance in combating climate change.

Tailpipe (or our case, smokestack) CO2 emissions, though, are essentially the same for HVO diesel and fossil diesel. Thus, unless we grow and refine the feedstock in Massachusetts this doesn’t help in achieving the Commonwealth’s 2030 goals. It should be noted that HVO combustion eliminates sulfur compound emissions and lowers particulates by as much as 30 per cent and nitrous oxide compounds by about 10 per cent.

The news reports imply that the Island Home will use HVO diesel exclusively for the upcoming three summer months at a stated cost of $62,400 at $2.99 per gallon. The Island Home is the least efficient vessel of the SSA fleet at 12.9 gallons/mile (per 2024 SSA data), and using the miles per WH-MV crossing and the number of trips per day for the 90-day period, it’s clear that the $62,400 cost represents less than 20 per cent of the runs.

Finally, there is the problematic refrain that we can’t have electrified ferries because Eversource cannot supply enough shoreside power or the SSA cannot afford to pay for such infrastructure. Even if that were true, the recent purchase and refitting of the Barnstable, Aquinnah and Monomoy vessels represents a major lost opportunity to deploy hybrid diesel-battery electric ships. Hybrid vessels do not require shoreside power, though without this the improvement in energy efficiency will be 20 per cent or less — still a real environmental positive as a bridge to plug-in hybrids and eventually all-electric boats.

In 2023, the Texas Department of Transportation put a new 293-foot, 70-car, 495-passenger hybrid ferry in operation that serves the city of Galveston. It does not currently use shoreside power, but was designed to use such power when it is eventually installed. A new-vessel strategy for the SSA should be formalized that includes this path toward future electrification.

The bottom line here: the HVO fuel trial is a laudable step forward. The use of this renewable fuel won’t get us to the Massachusetts goals for 2030 by a long shot. But hybrid boats plus the rapid introduction of renewable fuels will at least make it possible to meet the 2050 goals as part of our contribution to help mitigate the already-underway climate crisis.

Rob Hannemann

Chilmark