IT'S IMPOSSIBLE TO OVERSTATE DEFLATIONARY PRESSURES:

 Our guest today is Brad Plumer, a New York Times climate reporter specializing in policy and technology efforts to cut carbon dioxide emissions. He's also covered international climate talks and the changing energy landscape. [...]

MOSLEY: You write about this transition to clean energy, that it's happening faster than we might think. Can you paint a picture of your findings?

PLUMER: You know, things are moving at such an astonishing pace. So just a few things - renewable electricity, globally, is now expected to overtake coal by 2025 as the world's largest source of electricity. We keep seeing automakers openly talk about expiration dates for the internal combustion engine, talking about how they're going to make more and more miles go electric.

An astonishing stat was this year, about $1.7 trillion worldwide was going to be invested in clean energy technologies - wind, solar power, electric vehicles, nuclear batteries - compared with $1 trillion on fossil fuels. So the amount of money going into it is just staggering. And we keep seeing these records broken. You know, the International Energy Agency, for years, they would put out this forecast of how much wind, how much solar, how many electric vehicles they expect in the coming years. And every year, it would turn out that they just way underestimated the speed of the transition. So it's something that's caught even the experts who study this for a living by surprise.

Allwright says renewed interest in windships started to gain steam in the early 2010s, and today there are about 30 large commercial ships using one of a number of such technologies. Shipping giants Maersk and NYK are already experimenting with such systems. As many as 20 more are expected in the months ahead. So far, they are mostly "testbeds" to see if the concept is commercially viable.

In one recent trial, the 751-foot bulk carrier Pyxis Ocean operated by Cargill was retrofitted with two rigid sails, known as WindWings, inspired by those found on modern America's Cup racers. The vessel, carrying only water ballast, arrived in Paranaguá, Brazil, last month after an approximately 10,000-nautical-mile journey from Singapore.

The articulated fiberglass and metal wings, which stand 123 feet tall, use the force of the wind to create lift and move the ship forward. The wings can be folded on deck in case of unsuitable wind or heavy weather and while in port, where they would interfere with loading and unloading operations.

John Cooper, the CEO of BAR Technologies, which developed the WindWings, says it took considerable engineering and computer modeling to move the concept from high-tech racing boats to a commercial bulk carrier. On the America's Cup boats, "the hydrodynamic resistance is quite low," he says, compared to the "humongous" dynamic drag of a commercial ship.

On its first voyage last month after it was retrofitted, the 5-year-old Pyxis Ocean hit 16.2 knots (18.6 miles per hour) with the WindWings working in tandem with the ship's engine running at minimum power, Cooper says.

Before departing for Brazil, the ship even sailed briefly without the engine. "We pulled the anchor up, we put the wings up, turned them into their flying shape, and we cruised our way off berth," he says. "The crew were dumbfounded."

Variations on the rigid wing concept are being tried elsewhere. One system, first developed in the 1920s, is a bigger departure. "Rotor sails," or large carbon-fiber cylinders, move a ship along using a principle known as the Magnus effect, an aerodynamic force perpendicular to both the direction of the airstream and the axis of the rotor.

"I would say there's a competition right now," says Matthew Collette, a naval architect who teaches ship design at the University of Michigan. The wings on Pyxis Ocean are "more complicated, [but] potentially more efficient. The rotor sails are very simple, a little bit more limited in what you can do with them."

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