Le Meraviglie del Duemila (The Wonders of 2000), by Emilio Salgari
(Published 1907). Cover artwork by Carlo Chiostri (1863-1939)
In his prescient 1907 novel, The Wonders of 2000, Emilio Salgari described “huge floating islands… equipped with huge wheels similar to those of your old mills, and towed up to the Gulf Stream, mooring them firmly.” These turbines – for such they were – would take energy from the steady currents of the Gulf Stream and transmit that electrical power through “submarine cables, similar to those that you used for transatlantic telegraphy.”
While the prototype Gulf Stream turbines of today are not moored, like Salgari’s ‘mill wheels,’ but instead drift like kites some 80 feet down in the water column, his concept of using ocean currents to make electricity were spot on. Several projects beta-testing feasibility, turbine design, and cost effectiveness are underway to bring blue energy from the Gulf Stream to the mainland via cables – just as Salgari envisioned.
Of course, modern oceanography has revealed that the Gulf Stream is but one of many such currents in a vast global system. These oceanic rivers – some warm, some cold – transit every ocean and coastline on the planet. The Labrador Current. The North Atlantic Drift. The Kuroshio. The South Equatorial. The Mozambique and the Alaska; the warm Agulhas current flowing down the East Coast of Africa, and the cool Benguela running up the West.
Such currents are perpetuated by Coriolis winds, by variance in ocean depths, by salt gradients, and by temperature. They have been exploited over the years – for shipping routes, fishing, and comprehending global climate patterns – but never, up until now, for harvesting electrical energy.
Photo by Norman Kuring, NASA Earth Observatory.
Just as humanity harvests only a miniscule fraction of the 173,000 terawatts of solar energy continually falling on Earth, we have as yet to make use of the incredible kinetic energy produced by the world’s waters. The Florida-to-North Carolina section of the Gulf Stream alone offers an estimated 163 Terawatt hours per year (TWh/y) in renewable, carbonless power. For context, the United States uses 4,146.2 TWh/y, meaning just this stretch of the Gulf Stream, if fully exploited, could provide almost 4% of the nation’s energy needs.
That may sound small, but the Gulf Stream and others flow north along the southeast U.S. coast, while the California, North Pacific, and Alaska currents also cradle America’s shores. The Greenland current could potentially supply a significant chunk of that island’s needs, the Labrador borders all eastern Canada, while every other continent on Earth is touched at some point by these energy-rich oceanic rivers.
Unlike riverine hydropower though, oceanic turbines must be laid in salty, marine offshore environments, and the electricity harvested must be cabled to shore, a significant technical challenge. As the fastest-flowing ocean current – hence the one with the greatest electrical potential – the Gulf Stream is the logical place to start.
Artwork depicting a cable-tethered undersea turbine design.
Source: Wikimedia Commons
The U.S. Department of Energy’s Southeast National Marine Renewable Energy Center (SNMREC) at Florida Atlantic University has been studying problem and engineering equipment with an eye to accelerating commercial implementation of ocean current power generation.
There have been concerns that, as with fishing, dams, and other human activities, marine wildlife and even the Gulf Stream itself might be adversely affected by floating turbines. However, an exhaustive 2020 study by Ocean Energy Systems (OES), a subgroup of the International Energy Agency (IEA), studied this question and found that, as the Washington Post put it, such structures were “unlikely to harm marine life, change their habitats or affect the natural flow of ocean waters.”
There are threats to the Gulf Stream, however, and to its global family of currents, that could have impacts far beyond the viability of marine power generation. Some models have shown that climate change itself is destabilizing ocean current patterns planet wide. That would substantially impact climate, weather, marine migration, marine salinity, and a host of other critical systems across the globe.
In the meanwhile, Salgari, that champion of fictional swashbucklers everywhere, nailed both the need for more power, an accessible source just off the American coast, and a means for exploiting it. Bravo, signore, bravo!
 The U.S. Department of Energy estimates that all forms of marine energy – “wave, tidal, ocean current, ocean thermal, and riverine in all 50 states” – would render 2,300 terawatts annually, equivalent to “57 percent of all U.S. electricity generated in 2019,” enough energy to power 220 million households.