This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I don't doubt that you can extract energy from the ocean a little easier than from flying kites in the sky. It's the maintenance aspect of such devices that will be their downfall. Maintaining an onshore windmill isn't all that terrible (it is still required). Offshore windmills are more challenging. Underwater windmills? How much more expensive is it?
My boss learned a nasty lesson about seawater the first year he had his boat in the water. Barnies. Painting the hull solved this problem, but it is still necessary to clean the hull once a year or so to get the barnies the paint couldn't prevent.
Truly this is a well known problem. A variety of solutions are available to deal with them. All of the solutions are means of delaying the attack of the amazing array of ions available in the ocean.
Put an experience Marine Engineer into the room with this newest group of enginasters see if he can help them overcome the mundane issues surrounding the earths saving energy source.
The CNN article provides a good example of a propaganda trick used by Green-leaning journalists (I would assume Matthew Knight is an environmental journalist, but CNN don't seem to categorise their journalists), which is to make it look as though any not particularly well-known Green technology idea is brand new. I would assume they do this because politicians and funding agencies are more likely to throw money at something the newer they think it is, and it generally contributes to the overall bluff that some breakthrough in renewable energy is just around the corner.
The underwater kite idea has been around since the 1970s. It was invented by a Canadian ex-jeweller called Philippe Vauthier and he formed a company called UEK (Underwater Electric Kites) in 1981. This 2005 news article gives some details of the history:
You could even turn this journalistic practice into something that might go on JEB's list of laws:
The first rule of hyping of Green technology: If a Green technology is not yet established, present it as though it has just been invented in the last two years.
The second rule of hyping of Green technology: If a Green technology has somehow managed to become established (like wind turbines and solar panels), the technology is presented as making substantial technical progress from year to year and its costs are always on the verge of plummeting. By contrast any non-politically correct technology (like fossil fuel and nuclear power) is presented as though it is frozen in time and no technical progress has been made in the last fifty years.
You are so right about your "first and second rules of hyping of Green technology!
Yes. And judging by what one reads about nuclear power developments on the net, the greenies are in for a nasty shock in the next few years!