Gravity from the sun and moon tugs at the surface of our oceans, creating tides that move massive quantities of water across broad expanses of shoreline twice a day. All that moving water produces kinetic energy we can convert into electrical power.
Though all of the earth’s continents have shorelines and tides, we haven’t done much with all that energy. To date, tidal energy technology generally takes two forms:
- Tidal current converters. These devices are typically underwater turbines that look much like a wind turbine and capture energy from water moving past the blades.
- Coastal barrages. A barrage is a kind of dam across the opening of an estuary. It works much like a hydroelectric plant, except that it uses turbines to capture energy from rising tidewater rather than river water.
Current technologies offer only a glimpse at tidal energy’s potential. To get the whole picture, we need to weigh the pros and cons of tidal energy.
Here’s a quick summary: (more…)
It’s one thing to dream about the immense power residing in our planet’s oceans. It’s quite another to put human ingenuity to work tapping into the ocean’s powers.
That was the backdrop of the International Marine Energies Technologies Course, held in mid-March in The Netherlands. Some of the best minds in marine energy technologies gave presentations covering intriguing innovations in the sector. PMI was the only U.S. company attending the course.
At PMI, we’re fascinated with the potential of marine energy. We supply cable hardware to companies that do business in the deep sea, including seismic exploration firms that tow massive cable arrays to hunt for petroleum deposits below the ocean floor. Since we’re experts in hardware that can survive treacherous undersea environments, we’re eager to contribute to initiatives that tap the energy of our oceans.
Europe has a huge head start on marine renewable energy technologies. Offshore wind farms are now mainstream technologies along the coasts of many European nations. With that technology well understood, European companies are starting to look at other ways to draw energy from the ocean.
The course covered four technologies:
- Ocean thermal energy conversion (OTEC). This technology taps the massive amount of solar energy trapped at the surface of the ocean in the tropics. OTEC uses warm sea water to convert a liquid into steam that drives a turbine, producing electricity. After the steam passes through the turbine, it gets cooled by water pumped up from the ocean depths, condensing it back into fluid form to continue the cycle.
- Salinity gradient power. When fresh water bodies are near salt water bodies, there is a substantial energy potential that can be harvested. Through pressure retarded osmosis or reverse electrodialysis, electricity can be generated. Salinity gradient technologies are being developed in Norway and the Netherlands.
- Tidal power. The ebb and flow of ocean tides can generate substantial kinetic energy that can be converted into electricity by several kinds of technologies. Tidal energy depends on the velocities water moves. (See Massive Tides Invite Wave of Tidal Energy Research for more).
- Wave power. Where tidal relies on the velocity of water, wave power relies on the change in height of waves to harvest energy. (See Scotland’s Sunken Wave Turbines for more).
Each marine energies technology has pros and cons. While all can produce energy without the use of fossil fuels, they also face substantial challenges because of the chaotic and corrosive nature of oceans. Furthermore, they require substantial financial investments and must offer some hope of providing a return to investors.
Moreover, any devices placed in the ocean are entering an active ecosystem that must be protected. The sessions of the International Marine Energies Technologies Course addressed these challenges. The people attending included engineers, researchers and representatives of companies venturing into the emerging ocean-energy field.
So what was PMI doing in Holland for three days? Well, we supply cable hardware to companies that do business in the deep sea, including seismic exploration firms that tow massive cable arrays to hunt for petroleum deposits below the ocean floor. It’s a great business to be in, but we also recognize the necessity to tap into renewable energy sources in the years to come.
Since we’re experts in hardware that can survive treacherous undersea environments, we’re eager to contribute to initiatives that tap the energy of our oceans. Ocean energy technologies are barely off the drawing boards in the United States, but our European colleagues are getting devices in the water and starting to generate energy.
And that’s getting us energized about the power of our oceans.
Related: “Tidal and Wave Energy Industry Struggles With Harsh Ocean Environments”
Want more information about our experience at International Marine Energies Technology Course? Schedule to speak to a representative.
Fundy Bay is famous for pictures of fishing boats tilted on their hulls — run aground by the immense power of the world’s largest tides.
The waters of this scenic coastal inlet along Canada’s Nova Scotia and New Brunswick provinces rise and fall by more than 50 feet twice a day, every day of the year. That predictability is one of the key reasons why green-energy researchers are fascinated with the potential of converting tidal movements into electricity. Solar power goes dark after sunset and wind power rises and falls with moving weather patterns. But tides rise and fall like clockwork, creating the potential for an extremely reliable stream of electric power.
The Trouble with Tidal Energy
Unfortunately, the ocean is one of the worst places on earth to install mechanical equipment. Saltwater is extremely corrosive, and working on machinery underwater is incredibly dangerous and expensive.
Some wave and tidal energy projects are mounting turbines on the sea floor. This keeps the turbines out of sight, which is a boon to coastal views, but it also dramatically increases the costs of upkeep precisely because they are so difficult to access.
Floating Platforms: A Tidal Energy Alternative
Fundy Bay’s epic tides have made it a hub for working out these kinds of challenges in wave and tidal energy research. One alternative researches are exploring is mounting a turbine beneath a floating platform that’s moored to the ocean floor via cables. A turbine connected to a floating platform could have all of its machinery easily accessible from the platform rather than mounted on the sea floor, where the only way to reach it is with scuba divers or remote-operated vehicles (or both).
In March 2016, a Canadian firm called Dynamic Systems Analysis (DSA) helped launch a floating research platform called EcoSPRAY that will document how highly turbulent tides work. This, in turn, will provide clues to the best ways to deploy floating tidal energy platforms that have been moored to the ocean floor.
The platform is operating in the Grand Passage between Freeport and Westport, Nova Scotia, in the Outer Bay of Fundy. Sensors on the EcoSPRAY will track wind speeds, tidal currents and wave actions. A drag plate mounted on the bottom of the platform will simulate the thrust of an underwater turbine, DSA says.
Protecting tidal ecosystems
While floating tidal power platforms would be less visually pleasing than turbines mounted on the sea floor, they have the potential to be less disruptive to underwater environments. Mounting an underwater turbine is a major construction project, whereas placing anchor points on the sea floor for mooring cables could be far less disruptive to the coastal environment.
Protecting that environment is very much on the minds of Fundy Bay researchers. Fundy Ocean Research Center for Energy (FORCE), the Offshore Energy Research Association (OERA) and the Nova Scotia Department of Energy are all working together on a half-million-dollar program to determine the effects of tidal energy turbines this year.
This points to the future of wave and tidal energy, which may well depend on finding the best mix of high energy output, low cost and minimal impact on the subsea environment.
Related articles:
• EcoSPRAY tidal platform inspects moorings in high-tidal flows
• Fundy tidal energy study to look at seabirds, lobster, acoustic environment
Learn more about our Tidal and Wind Energy Efforts today:
The ocean is a big place. The equipment and tools we build for working in the subsea is pretty big too. And apparently there’s room to continue to grow – because projects like the massive Delta Stream Turbine by Tidal Energy are going to prove how big things are going to get. They built one the world’s first demonstration devices connected to the grid to generate green, renewable and predictable tidal power in an attempt to reduce the UK’s carbon emissions.
It weighs 150 tons, has a 52ft by 66ft frame, and each turbine has a 49ft diameter rotor which is connected to a generator to produce electricity both the ebb and flood tides.
Watch how it works:
Read our thoughts on the wave and tidal industry here.
Read more about Tidal Energy’s project here.
Although we are located in the States, we assist companies world-wide with marine cable hardware, deployment, and management. Therefore, we’ve had a front row seat watching Europe position itself as a leader and pioneer in addressing climate change, creating jobs in the offshore wind sector, and reducing fossil fuel imports.
And while offshore wind is years behind onshore wind, the industry is displaying one of the fastest growth rates in the industry. The pace of growth, however, needs to be matched by an equal pace in reducing costs. Success will depend not only on how much it can reduce costs, but also how fast it can reduce costs.
As the U.S. starts installing the foundations for their first offshore wind farm, they will have these same issues to contend with as well as the struggling opposition found along our coast.
Read more about offshore wind here.
Read more about North America’s first offshore wind farm:
Rhode Island’s Deepwater Wind will start installing the foundations for North America’s first offshore wind farm on Monday, a milestone the company says could pave the way for an industry long established in Europe but that is still struggling with opposition in the United States.
There is no shortage of new technologies and ideas in the wave and tidal energy business. New floating tidal platforms in the Netherlands are already feeding electricity to the Dutch grid almost upon deployment. The results are amazing and not yet seen in the tidal industry until now,
Their recipe for success is one we share – minimize the impact of equipment costs and grow with minimized risk. That’s exactly how we work customers to find a solution within budget and create top-quality cable hardware maintaining cable integrity in extreme underwater environments.
In a recent interview with Tidal Energy Today, Allard van Hoeken, Head of New Energy at Bluewater Energy Services, echoed our beliefs.
“Learn with low costs, grow with minimized risk, and keep offshore access easy in the early phase.” This recipe for success in tidal energy industry was shared with [Tidal Energy Today] by the Head of New Energy at Bluewater Energy Services, Mr. Allard van Hoeken.
Read the interview with Allard van Hoeken here.
There’s no shortage of bad news these days, but looking at the trends in renewable energy, there’s plenty of hope. Last year, the world broke a record for new wind installations, installing nearly three wind turbines each hour. At that rate the need for proven subsea equipment will certainly increase as well. At PMI, we are focused on this market, the trends that will lead the energy revolution and helping these customers realize a significant return on investment.
Wind energy is surging back to stronger levels of investment is just one of the trends. Read about all them here.
As engineers, we naturally love to innovate. That’s what is so exciting about what the future holds for us in alternative energy. While our subsea hardware has been proven for over 40 years, we are also equally proven in custom-engineering parts for unique cable innovations and ready to tackle what the future has in store for us.
Turbines designed in the UK aim to harness tidal energy to produce cheaper electricity − without endangering marine life.
Kepler Energy, whose technology is being developed by Oxford University’s department of engineering science, says the turbines will in time produce electricity more cheaply than off-shore wind farms.
It hopes to install its new design in what is called a tidal energy fence, one kilometre long, in the Bristol Channel. Read more…
