Boston outer-harbor barrier could generate tidal power
The Sustainable Solutions Lab at the University of Massachusetts Boston produced the “Feasibility of Harbor-wide Barrier Systems” report for flood damage reduction in Boston in May 2018. Two scenarios were studied that combined shore-based systems and a barrier-wide system in terms of the time when barrier construction would be complete.
Scenario 1 was for completion in 2070 with shorebased systems needing damage protection to elevation +14 ft. Scenario 2 finished construction in 2050 with shore-based systems protection reduced to elevation +12 ft. Also considered was whether “shore-based systems” were successful or not in reducing flood damage.
When evaluating the outer-harbor barrier benefits, even if the shore-based systems failed completely, the sooner the barrier could be constructed (Scenario 2 in 2050) the greater its benefits ($27 billion). For complete success of the shore-based systems, outer-harbor barrier benefits were $8.4 billion.
We propose Scenario 3. Barrier construction would be finished 20 years sooner — in 2030 — so needing 0.5 ft for sea level rise requires shore-based systems protection to elevation +10 ft. This provides 70 years of flood damage reduction benefits from a harbor-wide barrier to year 2100. Now the barrier benefits would be $50 billion if no shore-based systems can be finished in 10 years (2030) and even about $16 billion if they are all successful.
The SSL scenario analysis considered the integrated benefits of a combined shore-based system and harborwide barrier system. It recommended the shorebased systems approach for “the next several decades” but also recommended monitoring world-wide technology for storm surge barriers to determine if and when “re-examination of the feasibilty is needed.”
We believe its now time for re-examination.
To meet present-day and future flooding events due to rising seas, a design that combines flood damage reduction benefits of storm surge barriers with tidalflow turbines for renewable energy generation will make better economic justification. How does the outerharbor barrier work to reduce flood damage?
Sector gates rotate horizontally to seal the navigational channels. And secondly, vertical walls with multiple openings with gates permit daily tidal flows in the Mystic, Charles and Neponset rivers and harbor bays to minimize ecological change. Both types of gates would be closed only for a short duration, and within hours of a storm passing, the gates would reopen. Dunes further to the north and south sides would be strengthened to withstand the design storm.
This system is exactly what the Dutch employ to protect against flooding of the Netherlands. All five storm surge barriers in the Netherlands were closed during a North Sea storm of January 3, 2018.
By modifying the design of the tidal-flow gates to incorporate turbines that generate electricity, an endless source of funding is created to help pay for the cost of the project. Each opening in the barrier wall would contain both a gate for closure during storms and one (or more) turbines. Tidal-flow turbines in the East River between Manhattan and Queens in New York City have been generating electricity since 2006. The Dutch have operated five tidal-flow turbines within one gate openings of the famous Eastern Scheldt storm surge barrier to generate electricity since 2015.
Tidal energy is the most efficient renewable energy source with no downtime for no sun or no wind or no waves. Now is the time to adapt the outer-harbor barrier design to include tidalflow turbines to generate electricity. By constructing the country’s first combined storm surge barrier to reduce flood damage with tidal-flow turbines to generate electricity, Boston would become known for how it helped — for the first time in the U.S. — to solve the problem of funding the high cost of a storm surge barrier.