Dream of green ocean paradise at hand
It is the stuff of the greenest of dreams: interlocking artificial islands outfitted with almost every renewable-energy technology imaginable, flowing thousands of megawatts of power along submarine cables to shore while supporting fish and hydroponic vegetable farms, and each day pumping millions of litres of salt-free water on to docking supertankers.
This is the future according to London-based architecture and engineering group Energy Island, which has taken on the mantle of 19th-century renewable-energy pioneer Jacques Arsène d’Arsonval in the hopes of yoking together ocean thermal-energy conversion (Otec) technology with wind turbines, solar-power towers and wave-energy devices to create multi-megawatt (MW) offshore-generation and desalination plants.
Energy Island — a consortium involving father-and-son architect team Dominic and Alex Michaelis, Vega Consulting, the University of Southampton, Halcrow Group, Noble Denton and Parsons Brinkerhoff — has designed a 50MW ‘float-alone’ concept that combines electricity created using Otec — a technique that uses ‘flash evaporated’ seawater to drive turbine generators — with arrays of off-the-shelf renewable-energy technology.
The concept goes far beyond power generation, as a 250MW Otec plant would produce just under 600m litres of drinking water a day. Designed as hexagonal structures, the concrete-and-steel island platforms could be bolted together to form self-sufficient archipelagos complete with housing developments, fish farms, greenhouses, harbours and eco-tourism complexes, with huge volumes of surplus water and electricity flowing to shore via submarine lines.
Though building the grandest vision of the one-gigawatt (GW)-plus energy island may still be decades ahead in the future, discussions are progressing to float out a first, smaller-scale unit off the Philippines or the Maldives, according to Energy Island managing director Alex Michaelis.
“We’ve had initial meetings with the owner of a couple of the islands [in the Maldives] who is committed to doing something by 2020,” says Michaelis.
“Though you are looking at an area of around 300,000sq km, it would actually take only one or two [energy] islands feeding water and electricity to these two. Added to this are the possibilities for much-needed land reclamation by pumping up sand. It is entirely feasible, and would be quite interesting to work out.”
The Maldives project, he notes, has the “ideal conditions” for a maiden outing for the technology, as the Otec plant depends on tropical offshore environments where surface water is higher than 25°C and deep-water temperatures at least 20° cooler to drive steam-powered turbines while producing desalinated water via a cold-heat exchanger. “Until we have some further meetings, we can’t say exactly what megawattage of project we are looking at, but it will be pilot-scale,” suggests Michaelis.
While Energy Island is keen to press ahead with its plans in the Maldives, it is also in negotiations with numerous national public-water authorities — including those of China, Brazil, Mexico, Oman, India and Pakistan — with a view to getting a first industrial-scale development off the drawing board.
Though US president Barack Obama has sanctioned grants to two Otec projects in recent months, Michaelis reckons the energy island concept “fully realises” the greater potential of ocean thermal energy by combining it with existing renewable technologies.
“People are beginning to prick up their ears [to the potential of Otec], but we are saying let’s go further,” he stresses. “Let’s take wind, wave, solar — everything and anything we can use in terms of renewable-energy technology — and use it.”
Current thinking leans towards using concentrating solar-power towers and compact wind turbines installed topside on the energy islands, while wave-energy converters will feature on the ‘shorelines’, and cowled ocean current turbines will sit below the surface.
The island could also build in marine geothermal-energy generation by using a modified oil-drilling kit to tap into warm aquifers or sub-surface rock channels offshore.
Despite the ambitious scope of Energy Island’s project, there is a perceived value in starting small, according to Michaelis.
“The advantage of starting with a relatively small-scale project would be in tweaking anything that may go wrong [with the various technologies], rather than leaping straight into a 50MW one and finding one component or another is exactly the right thing.”
That said, no technology foreseen for installation on an energy island is actually unproven. Even Otec has been successfully put through its paces at a sizeable scale, with an open-cycle, 210-kilowatt facility designed and built off Hawaii by Luis Vega, having generated electricity for five years in the 1990s.
“Otec is one of those rare renewable-energy technologies that has provided power on a base-loaded level,” emphasises Energy Island head of business development Michael Khoury.
“This is why we conceptually put it up there as something that could compete with nuclear power.” Khoury points to the fact that, unlike most other forms of renewable-energy technology that vary in output according to cycles of day and night, and of changes in weather conditions, Otec-based energy islands can flow power and desalinated water 24 hours a day, all year round.
“We have been discussing the potential [of the energy island] with utilities from around the world,” he continues. “The prototype has been proven [through Vega’s Hawaii project]. We now only need our first commission — and we feel that’s not far off.” Promisingly, the price tag on an energy island project is coming down. Early costing put capital investment at more than $500m for a 50MW development, but already Michaelis is thinking that the possibility of using off-the-shelf technologies — whether pumps, pipelines or solar-power towers — means the outlay needed to bring on line a large-scale energy island “will be substantially lower than first calculated”.
“Clearly, there is a nervousness about spending these sums of money,” Michaelis acknowledges, “but for many of the countries we are talking about — China, India and so on — water supply is absolutely critical, and our concept produces energy and water, as much as you will ever need, so the investment will be paid back.
“There is definitely a great deal of good will [being shown].”
And well there might be — present energy-demand levels could be met by 52,000 250MW energy island plants dotted about the world’s oceans.
“When I started working on this project two years ago, I thought it would be matter of weeks before someone came up and said: ‘Here’s why it won’t work.’ But no-one has,” says Michaelis. “It [the energy island] is an entirely viable idea, and I think in 25 years, we are going to wonder why it took so long to the get the first one going.”