Gulf Stream gold: Mining green energy from Atlantic currents

Scientists hopeful for renewable potential from sea turbines, environmentalists concerned about impact on marine life

A rendition of the experimental test configuration to be deployed to measure effects of turbines on a marine environment.
Sharks and other fish circle in Atlantic waters.
Stephen Frink / Corbis

The Gulf Stream meanders clockwise from the Gulf of Mexico, past the mid-Atlantic coast toward Europe. It is one of the most powerful currents in the world, and it is full of life.

Many species of pelagic fish, endangered marine turtles and other marine organisms roam the relentless conveyor belt of warm blue water unhindered, flowing beyond the shores of Florida. Their travels were relatively unhindered — until now.

Landbound humanity is hoping to capitalize on the Gulf Stream’s fast-flowing waters, eyeing them as a potential source of endless power and a possible solution to Florida’s energy needs. A pilot project to test a variety of electricity-generating turbines right in the middle of the Gulf Stream has been given the go-ahead in the form of a five-year lease to Florida Atlantic University (FAU). The lease covers 1,000 acres right in the flow of the current.

The environmental upside is obvious. It is believed the Gulf Stream has the potential energy — from a clean and renewable source — to supply Florida with 35 percent of its electrical needs, according to the U.S. Bureau of Ocean Energy Management (BOEM).

However, there is also concern that there might be an ecological downside. According to a detailed report issued last summer by BOEM, the environmental impact would be minimal. But no one wants to take any chances as the global quest for clean energy aims to bring full-scale commercial deployments of devices, turbines and cable-to-shore systems in the ocean. Many believe it still remains uncertain how life in the current will respond if the industry takes off in a big way and suddenly turbines become a common part of the underwater world.

So the FAU project is aimed at finding out exactly how marine life might react, and prove if it is possible to generate power from the ocean current. “Because there is so little known in certain areas, there is a tendency for everybody to protect everything at all costs when the data may say something else,” said Susan Skemp, executive director of FAU’s Southeast National Marine Renewable Energy Center (SNMREC).

One area of research looks at how schools of fish approach the structures. After all, neither the fish nor the turbine companies want any marine life caught up inside the machines' whirring parts. “It may indicate that the fish are naturally curious, but once they get within a certain distance of an operating system, they may be repelled by it and may move away from it, so that's all part of the research,” Skemp said.

FAU’s project is going to be a serious test bed for a whole new industry. The scheme is trying to bridge the gap from lab to market by encouraging private companies to launch their turbine prototypes from FAU research vessels, which will be moored for weeks at a time, collecting measurements of ocean conditions. Three floating test berths will be connected to buoys anchored to the ocean floor. So far, the center has nondisclosure agreements with over 40 private companies, but “six to 10 have prototypes that are ready for field testing,” said Gabe Alsenas, program manager of SNMREC.

Companies are lining up for offshore testing, which is to take place later this year. That’s when FAU plans to prove that its 5,000-pound turbine will generate electricity. “What is realizable will depend on the systems that are built, and also what environmental regulatory processes we need to have in place,” said Skemp.

SNMREC's test turbine.

But environmentally, very little is known about life from the seafloor to the surface. SNMREC hopes that by deploying these single-device prototypes, it will be more able to predict how an array of permanent industrial equipment in the water column would put the ecosystems at risk.

One company that has already signed an agreement with FAU is Minesto, a Swedish firm that has produced electricity from its prototype, called Deep Green. The unit resembles an underwater kite and a turbine that is tethered to the ocean floor. While the current lifts the kite, a rudder is supposed to guide it in a trajectory shaped like a figure 8. A quarter-scale model is currently undergoing sea trials in Strangford Lough, Northern Ireland.

“Theirs is a tidal system, and they haven’t done it with ocean currents yet. So they will have to revise the design to make it applicable to this type of system,” said Skemp.

A distinctly different design would use a combination of small turbines encased in a large honeycomb-shaped device made of Kevlar and carbon fiber. Bruce Heafitz, CEO of Ocean Current Energy, said the lightweight turbines would have much lower maintenance costs than their competitors. “We’ll suspend this honeycomb structure from the ocean floor and bring it up to the top, where the current is equivalent to 200-mile-an-hour wind force,” said Heafitz.

But even as the focus is on designing the most efficient turbines — which undoubtedly produce “clean” renewable energy — the emphasis on environmental protection is also key. “Environmental groups really do support what we’re doing in terms of renewable energy, because it’s green and clean. But they are concerned about any ancillary affects to corals, marine species, and we’re trying to alleviate those fears in terms of development,” said Camille Coley, associate director of SNMREC.

Several years ago, when wave energy farm proposals were contemplated in California, the research and tracking of gray whales as they migrated past the San Francisco shoreline helped provide key information.

In Florida’s waters, all 16 populations of marine turtles are on the endangered species list, yet their lives remain mostly a mystery.

Jeanette Wyneken, an FAU marine biologist, is heading up a long-term, systematic study of marine sea turtles to answer basic questions about how these protected animals use the Gulf Stream.

“We need to know what is normal. And it’s complicated, to say the least. These species take 25 years to mature, and we have to look at variations in population over 10 years. Water temperature is a major factor in determining the sex ratio of the population — not only that, but climate and seasonal effects too,” said Wyneken.

Many believe the best approach to avoid negative environmental impacts will be some sort of adaptive management system as described by a 2009 U.S. Department of Energy report. As projects expand from small to commercial-scale developments, repeated evaluations of monitoring results will be crucial.

Skemp, who spent nearly three decades in the aerospace industry before heading SNMREC, said the state of ocean current technology is comparable to where space research was decades ago.

“We’ve got to be able to answer that question: What will be the interactions between the developer’s hardware and the marine ecosystem?" asked Skemp. "We don’t have the answers yet.’’

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