by Larry Smith
Well-known shipping expert Bill Bardelmeier spoke to a group of Rotarians last week about getting power from the sea. It's something he's been touting since the 1960s.
A retired marine consultant, Bardelmeier has lived here for half-a-century and was a director of the Bahamas Maritime Authority for over a decade. One of his pet interests is something called ocean thermal energy conversion, and, curiously, there's a lot of local lore behind it.
OTEC is a 19th century idea that uses the sea as a gigantic solar collector, but it has proved difficult to implement - for both technical and economic reasons. Some experts are now saying that its time may have come.
They argue that technical advances and economic changes have made OTEC a cost-effective alternative to fossil fuels for many tropical island communities. And in addition to electricity, these systems offer the bonus of producing fresh water and hydrogen, as well as nutrients for mariculture and agriculture.
"It has long been known that some of the sun's energy can be re-captured at sites where there is a substantial difference in sea water temperature (say about 40 degrees Fahrenheit)," Bardelmeier told Rotarians. "This re-captured heat energy can be used to generate electricity."
Essentially, an OTEC plant pumps warm surface sea water into a tank. The air in the tank is pumped out to create a vacuum, which vapourises the water. The steam spins a turbine to generate electricity, and then passes through a heat exchanger where it is condensed - by cold water pumped up from the ocean - into fresh water.
And from the sound of things, the Bahamas is just about the best place on Earth to locate such a facility. As Bardelmeier pointed out, the ideal OTEC site must be within the tropics, have a steep drop-off where the water plunges to over 3,000 feet, and be close to a power grid.
"In essence this describes the southwest corner of New Providence," Bardelmeier said. And in fact, that's where E. P. Taylor's New Providence Development Company planned to build an OTEC plant about 40 years ago.
Taylor was the Canadian investor who developed Lyford Cay. And in 1966 his NPDC was run by an engineer named John Bainton - a long-time friend of Bardelmeier, who shared his interest in ocean thermal energy conversion. Bainton died in 1989 at the age of 63, but his widow, Aileen, still lives at Lyford Cay.
In fact, Bainton went so far as to charter a Deepstar research submersible to dive to the bottom of the Tongue of the Ocean. And in 1967 he commissioned one of Canada's top engineering firms to study the feasibility of an OTEC facility at Clifton - just west of the BEC power plant.
The idea was to develop a 10,000 kilowatt sea thermal power plant that would also produce 6 million gallons a day of fresh water. Back then, the construction cost was estimated at about $19 million (assuming duty-free imports).
"Jack gave a talk about it to one of the service clubs," Bardelmeier told Tough Call. "But no-one got very excited. They spent a lot of money, and had some innovative design ideas, but it never lit off. Jack was ahead of his time."
One of the stated reasons for Bainton's interest was the possibility that NPDC might get into the aragonite mining business, which needed a supply of low-cost power. Aragonite is a sand formed by chemical precipitation in the ocean and huge amounts are deposited onto the Bahama Banks. Mining of this resource was introduced near Bimini in 1969.
Lerner Marine Labs of Bimini had the initial concession but turned it over to Union Carbide, which sold it to the Dillingham Corporation, a big US construction and engineering firm. The idea was to supply millions of tons of pure Bahamian sand to cement manufacturers and glassmakers on the US eastern seaboard. Bardelmeier was Dillingham's shipping advisor at the time.
"Cement-making was a cheapy big market," Bardelmeier recalled. "You had to deliver a ton of aragonite to General Portland Cement in Tampa for $2. That meant 90 cents per ton for freight, which was pretty skinny. So the netback to Ocean Cay was maybe $1.10 per ton. Profitability lay in producing at least five million tons a year."
And coincidentally, in 1979 Dillingham was involved in building a floating OTEC prototype plant off Hawaii. That was soon after the Arab oil embargo of 1973 had spurred intense interest in renewable energy systems.
After Dillingham sold its Bahamas aragonite operation, Bardelmeier tried to enlist Willard Rockwell, the chairman of one of America's largest technology companies, who had become famous for his role in building the Space Shuttle. Rockwell owned a vacation home at Cat Cay, an upscale resort close to the aragonite concession at Ocean Cay.
"He came to Nassau in his 'copter one day and landed right across from our office at the Pilot House, climbed our fire escape and pounded on the door." Bardelmeier said. "Unlike the other Cat Cayers who didn't welcome the industrial sights at Ocean Cay, Rockwell thought he might buy the aragonite project, but after a lot of research he backed off."
Bardelmeier exploited the contact with Rockwell to present his own proposal for an OTEC plant at Clifton. In 1984 he told Rockwell that such a facility would be capital intensive, but once built would have virtually no maintenance, labour or fuel costs.
"At the southwest corner of New Providence is an area of shallow heated sand flats which adjoin a 6,000-foot-deep underwater canyon," Bardelmeier wrote in his proposal. "Onshore at this point is the government-owned electricity plant with its existing distribution systems...and the cost of electric power in Nassau is among the highest in the western world."
His proposal called for a private corporation to negotiate a 40-year contract with the government to build a 40,000kw OTEC power station at Clifton Cay, both as a demonstration project and to sell power to BEC. He added that the US government might be willing to help fund the project. But Rockwell turned him down.
In those days the most expensive parts of an OTEC plant were the large-diameter cold water pipes which would have to extend for a length of 14,000 feet to a depth of 3200 feet to draw cold water. There was no experience then in laying pipe to such depths, but nowadays engineers can lay large-diameter pipe to much greater depths.
This became evident a few years ago when investors proposed replacing the barging of fresh water from Andros to New Providence with a 30-mile undersea pipeline through the Tongue of the Ocean. But independent experts said the pipeline was an untried technology compared to the reverse osmosis plants favoured by the Water & Sewerage Corporation.
"We know exactly what an RO plant costs, how to build it, and how it works. They operate worldwide and produce drinking water in 10 Caribbean countries successfully."
This is essentially the same argument used when comparing ocean thermal energy with conventional fossil fuel power generation. Despite the fact that French Scientist Jacques D’Arsoval described the OTEC concept over a century ago, there has been slow progress in developing the engineering systems to realize its potential.
But at least one Bahamas-based investor is interested. Frank Crothers of Island Corporate Holdings is a major shareholder of Caribbean Utilities Company in the Cayman Islands (as well as serving on the board of a zillion other companies).
Cayman's proposed plant will produce 10 megawatts of electricity and 3 million gallons of fresh water per day. The utility has a memorandum of understanding with the Baltimore-based Sea Solar International, and officials are saying that OTEC electricity could be produced within three years.
Currently, no OTEC plant operates at a commercial scale equivalent to conventional power stations or wind and mini-hydro plants. But there is a lot of interest in Pacific islands like Hawaii, which has a leading-edge OTEC laboratory where working models have been proven and a deep cold water pipe is already in place. In fact, Hawaii exported about $17 million worth of desalinated deepsea water in 2005, marketed as healthy, pure, mineral-rich drinking water.
Experts say OTEC facilities can reuse cold outfall water for air-conditioning, refrigeration, agriculture and mariculture. For example, David Melville, a long-time investor on Rum Cay, grows organic wheat grass at his Port Nelson home using only the nutrients contained in deepsea water provided by a Florida company in which he owns shares (www.oceangrown.com). And a few years ago, another American investor proposed an OTEC scheme for Inagua that would have used deepsea water to grow several commercial marine species on land.
But Bardelmeier says the Bahamas is not tracking scientific developments in the renewable energy field: "Perhaps it would be a worthy role of government to create a small, non-political entity to monitor the global scientific community and disseminate studies to the public domain, rather than treating them as secrets or leaving them to gather dust on a shelf," he told Rotarians.
"It is only a matter of time before some of the venture capitalists who constantly pass through or live here take a hard look at building a modest OTEC plant to sell power to BEC and get in on the ground floor of what may well be a widespread island industry around the globe in the next two decades."