The offshore wind industry has fresh guidance on using reliable standards to determine the best depth for burying offshore wind farm cables.
In February 2016, the Offshore Wind Accelerator based in the U.K. published advice to offshore wind farm operators to help them ensure they are burying their power cables at a safe depth. This is a serious concern because power cable damage is one of the most common costs that threaten the success of offshore wind farms.
The advice is in the “Application Guide for the Specification of the Depth of Lowering using CBRA.” CBRA means “Cable Burial Risk Assessment Guidance” — which uses predictive modeling to help offshore wind operators get a greater handle on the risks of offshore cable burial. The hope is that CBRA will help the entire industry thrive by addressing the need for reliable, consistent cable-burial practices that are the standard across the industry.
Standardized offshore cable burial also can help fishing fleets, shipping lines and offshore oil developers reduce the risk that their operations will damage the cables tethered to offshore wind farms. Read more on the promise of new CBRA guidance in this update from Maritime Journal.
As a leading provider of subsea equipment, PMI is helping the offshore wind power industry address its cable safety concerns. Contact us for the facts on offshore wind cable hardware designed to withstand the rigors of the deep sea.
Have questions about your offshore wind power cables? Need tips on how to extend the life of your subsea cables? PMI has the answers – check out our free guide to Extending the life of you subsea power cables:
Perhaps, though it’s probably a decade away. A recent article in the Virginian-Pilot of Norfolk, Virginia, explained that scientists are studying the waters off Cape Hatteras, North Carolina, one of the most powerful flow points in the Gulf Stream, to see if there is a way to harness that energy.
Figuring out how to do that would be a triumph of offshore energy engineering. While ocean wave energy is considered a promising source of renewable power, drawing energy from individual currents within our oceans is still mostly an idea on the drawing board.
The Virginian-Pilot article sounds a note of caution: “So far, no commercially connected turbines operate in the Gulf Stream, according to the Bureau of Ocean Energy Management. A few prototypes have been tested off the coast of Florida. Challenges include turbine maintenance in a harsh, salty environment and long distances to run cable connections.”
One expert quoted in the article said the Gulf Stream’s flow is strong enough to power all of North Carolina (population 9.5 million) and more. That’s makes sense, given that the Gulf Stream transports more water per second than all the world’s rivers combined, according to National Oceanic and Atmospheric Administration.
At PMI, we are monitoring all the developments in marine renewable energy. Companies are already proposing turbines for inland rivers, so it stands to reason that ocean current development could follow in that path. As these technologies advance, we’ll be poised to provide tough, durable cable hardware to ensure that power finds its way to land safely.
The offshore wind industry made significant strides in Europe last year, according to the European Wind Energy Association (EWEA). This growth has broad implications both for the renewables industry and the subsea cable market.
EWEA’s “Wind in Power: 2015 European Statistics” report published in February 2016 said European offshore wind installations more than doubled in 2015 from the year before. Germany had by far the most wind-power activity in 2015, adding 6,013 megawatts of generating capacity — and 38.4% of that was offshore.
Offshore wind installations accounted for 33.4 percent of all installations in 2015, according to EWEA’s data, up from 13.7% year before. Furthermore, investments in wind power hit an all-time high in 2015, EWEA said, with offshore wind leading the charge.
“Financial commitments in new assets reached a total of €26.4 billion, a 40 percent increase from 2014,” the report said. “While investments in new onshore wind generating assets increased by 6.3% in 2015, those in the offshore wind sector doubled compared to the previous year.”
A summary of the report in the website OffshoreWIND.biz notes where most of the capacity was added in 2015:
- Germany: 2,282 megawatts (75.4%), a four-old jump from the year before
- UK: 566 MW (18.7%)
- Netherlands: 180 MW (5.9%)
Another EWEA report, “The European Offshore Wind Industry — Key Trends and Statistics 2015,” drills deep into the details of the continent’s offshore power industry. It notes that “total investments for the construction and refinancing of offshore wind farms and transmission assets hit a record level of €18 billion.”
At PMI, we’re watching the growth of offshore wind closely because it has the potential to affect all the players in the subsea cable market. After all, those wind turbines depend on offshore cables to transmit power back to the mainland (the average turbine site was 43.3 kilometers from shore in 2015, in 27.1 meters of water). As sites near shore become more fully developed, offshore sites will inevitably move farther away and into much deeper water.
Those developments mean offshore cables and equipment like subsea cable terminations will need to be extremely tough and reliable — the two signature qualities of PMI cable equipment.
The coast of Scotland has some of the world’s strongest waves, which makes it a vital testing ground for wave turbines that convert wave movements into electricity.
So it’s no surprise that the Pentland Firth region of the Scottish coast is the site of the $1.5 billion MeyGen turbine project, where offshore cables are being laid in the opening phases of an initiative that aims to install 279 wave turbines below the surface of the ocean. As a recent Quartz.com report noted, the project could provide up to 400 megawatts of electric juice that could power 175,000 homes.
The wave-power turbines look much like wind-power turbines. Moving waves turn the turbine blades, generating electric power. Some observers say wave-power technology is about three decades behind wind power. But the MayGen project could signal the arrival of wave technology power, once it gets up and running.
Wave power technology is taking a wide array of shapes. Some devices look a bit like mechanical eels floating on the surface of the water; others are more like paddles that flow back and forth with the waves, moving a piston that generates power.
The ocean is an alluring power source, because it is so much denser than air and can therefore generate far more movement that can be converted into electricity. But even with 800 times more density than air at the surface, the water in the ocean creates an extremely problematic environment for energy development.
“People say this is not rocket science,” says Neil Kermode, managing director of the European Marine Energy Centre. “No. You fire a rocket into a nice, cold vacuum. We’re trying to do things in a salty, grit-filled electrolyte that’s got animals in it.”
Indeed, waves flow in multiple directions, unlike the wind, and the undersea environment could potentially be damaged by these kinds of projects. These and other factors vastly complicate wave-power generation.
Right now, cable-laying equipment is installing the offshore cables that will convey power to the people of Scotland after the wave turbines are up (well, down) and running. While power cables may not seem as exciting as subsea turbines, they still represent one of the most vital components of the project.
As wave power advances, PMI will be poised to provide durable ocean cable hardware to help these kinds of projects succeed. We have the experience and knowhow to design and manufacture rugged cable accessories that can last for years in the most difficult ocean environments. As the energy world transitions from fossil fuels to renewables, PMI cable hardware will be there every step of the way.
Elsewhere on the PMI blog: Tidal and Wave Energy Industry Struggles With Harsh Ocean Environments
Related article at Environment360 published by Yale University: Will Tidal and Wave Energy Ever Live Up to Their Potential?
Subsea power grids require two major kinds of ocean equipment: subsea power cables to convey electricity to the grids, and generating equipment to distribute electricity to pumps and other devices required to find and extract crude oil.
Even in a time of depressed petroleum prices, oil companies still value deep ocean engineering and they like the prospect of placing power grids on the sea floor because the grids improve the efficiency of the extraction process, which helps hold the line on production costs. When the oil market inevitably rebounds, companies with the most efficient production processes will reap the greatest rewards.
Let’s look at some of the ocean hardware that will go into these subsea systems:
- Transformers: These take power from the surface — either from the mainland or a floating platform — and convert it into the voltage needed at the undersea grid level.
- Switch gear: Switches adjust the flow of electricity to the deep-sea components that need it. If a pump needs different voltage than a compressor, switch gear takes care of that job.
- Variable-speed drives: An oil-drilling pump needs to run at multiple speeds to achieve maximum efficiency. VSBs make this happen.
- Cables: Cables carry energy from the surface to the grid and distribute it to the transformers, switch gear, variable-speed drives and any other ocean hardware in the grid.
Why deep-sea power grids are so attractive
Oil drillers need a lot of power to extract oil from below the deep sea. A deep-sea power grid allows power to be distributed to dozens of pieces of subsea hardware across a wide expanse of the sea floor.
A site developing a deep-sea oilfield becomes much easier to operate if power sources are on the sea floor near the point of extraction. Without a grid, power can be sent down via cables to equipment within a very limited expanse. A grid dramatically expands the area of sea floor that has available power.
Challenges for deep-sea equipment
Companies are designing subsea grids that can operate for up to 30 years in up to 10,000 feet of water. That places immense pressure on the equipment and requires precise engineering to protect delicate electrical components.
Saltwater is extremely corrosive, and undersea creatures like to attach themselves to any structures they can find. Fishing fleets drag deep nets that can become entangled in deep-sea equipment, and ship anchors have the potential to damage or cut subsea power cables.
Robust ocean equipment is the answer
Subsea energy companies understand the extreme terrain and know they need to build robust gear to provide reliable systems that can last decades. That also means they need to rely on proven ocean hardware that is high quality, highly reliable and fully flexible.
Offshore renewable energy solutions might be new to the world, but we know that all ocean equipment requires deep ocean engineering experience. And for over 60 years, PMI Industries has provided ocean hardware that increases efficiency, reduces failures, and improves installation and deployment time.
Waves and tides offer some of the most predictable, consistent, and just generally big energy resources available. However, rollouts of actual wave and tidal energy power installations have been slow. Part of the reason for this is that there is no consensus at all on what represents the best device designs to actually harness waves and tides and therefore on what subsea equipment is necessary to use.
Any subsea equipment needed to harness tidal energy is going to be expensive – and will tend to drive building costs to be anywhere between 3 to 15 million dollars and sometimes more. But in the long run, the investment will pay off.
Now the pros and cons of tidal energy always bring debate – but tidal energy has a lot going for it:
Consistent Power – Tides move constantly throughout the day, which provides a consistent stream of electricity generation capacity.
Pollution-Free – By taking advantage of only the tide, tidal power creates no greenhouse gas emissions or water pollutants.
Renewable – No material resources are used or changed in the production of tidal power, making it a truly renewable power form.
Minimal Visual Impact – Tidal power devices are fully or nearly completely submerged in water well offshore. This reduces the “damaging of water views” that has been associated with offshore wind turbines.
Efficient – Tidal Power converts roughly 80% of the kinetic energy into electricity, as opposed to coal and oil which convert only 30% of the energy held within.
Locations – There are numerous locations for tidal power around the world. Other websites online have this number at 40, however the coast of British Columbia, Canada has 89 alone.
And most importantly it offers low operating costs – Once installed, there are few ongoing operating costs or labor costs. By making investments at the forefront and building these systems properly with reliable equipment, tidal energy power plants offer a long lifespan, ultimately reduce costs, and make tidal energy more cost-competitive in the long run.
Whether they are lifting oil from deep below the seabed or experimenting with data centers on the ocean floor, anybody getting work done below sea level lives in perpetual fear of subsea equipment failures.
This is especially true as oil-development machinery equipment installed decades ago reaches the end of its projected operating life. What do you do with 20-year-old machinery that was built to last 20 years? Replace it now or wait for it to fail?
Either way, it will not be cheap. How can companies mitigate the risk of subsea equipment failures? A few tactics spring to mind:
Dive deeper into predictive maintenance
With today’s high-powered computers, databases, and networks, it’s getting much easier to collect data that will provide authoritative data on the likely expiration of subsea equipment. Of course this requires sensors that measure the conditions of equipment, and cabling to convey all that data to the surface.
It’s not an easy or a quick fix, but it should be built into any process of replacing or upgrading any new equipment being installed now. Forward-thinking drillers who do this today will reap far more benefits when oil prices inevitably recover.
Invest in more in-depth training
Subsea equipment fails for highly specific reasons that might be invisible to people who make routine checks and are trained to look for only a few data points. The key is to amass the knowledge of your most senior technicians and develop protocols to pass their advanced knowledge onto your junior technical staff.
Again, the oil market downturn can be a boon to advanced training because you can provide more in-depth training to smaller technical staffs. When repair and maintenance crews have to be ramped up in a year or two, you can implement your advanced training regimen to a wider audience.
Broaden your approach to integrity management
Integrity management has three anchors: inspection, maintenance and repair (IMR). You want to address all three holistically so that any change in one anchor is reflected in the others.
Deep-sea inspections can be logistically difficult and repairs can be disastrously expensive. That’s why so many companies are turning to data to help them understand the likelihood of failure so they can get every last minute out of a piece of subsea machinery but replace it before it actually fails and causes massive downtime or, worse yet, an environmental disaster.
There’s no question that all phases of IMR are costly, but the consequences of neglecting IMR are far worse. There will always be a temptation to cut corners on the quality of your subsea equipment, but these short-term savings can get extremely expensive if the equipment fails unexpectedly, endangering investments, ecosystems and people’s lives.
As a leading underwater engineering company, PMI has more than four decades of experience in creating subsea hardware for the oil and gas industry. Our track record of providing world-class cable hardware also can be a huge advantage companies in the emerging fields of offshore wind and tidal energy.
The island nation of Iceland has more renewable energy than it needs. Great Britain wants to use more power from renewable sources. A 1,000-kilometer submarine power cable could conceivably help Iceland export its surplus renewable power and help Great Britain meet its renewables goals.
All this is possible because of the advantages of high-voltage direct current (HVDC), which makes it more practical to transmit power over long distances via submarine power cables. Electrical grids around the world generally use alternating current (AC) because it’s more economical over short distances.
The problem with AC is it becomes less practical the farther the power has to be transmitted. When power has to be transmitted distances in measuring in the hundreds of kilometers or more, it becomes much more sensible to use high-voltage direct current.
Using HVDC to move lots of power over long distances is extremely helpful in developing nations like China that have rapidly emerging energy demands. But another of the great opportunities for HVDC lies deep below the ocean with subsea power cables.
Long-distance subsea power cables have a host of applications:
- Windfarms located far offshore. Wind is more abundant far away from shore, and many near-shore sites have already been developed. Submarine power cables using HVDC make these remote windfarms practical.
- Subsea electrical grids. Electrical grids beneath the ocean are being developed to improve the productivity of off-shore drilling operations. HVDC could allow them to be powered by production facilities on dry land.
- Metro areas where it’s impractical to build new power plants. In the San Francisco Bay Area, for instance, subsea power cables can extend power across the bay and avoid the need to build new power generating capacity.
This potential sounds awesome until you hear the statistics on how long it takes to repair a damaged submarine power cable. It can be days, weeks or months depending on the location and the severity of the damage.
The rugged reality of deep-ocean engineering is that it only takes one fishing trawler or cargo ship anchor to foul up a deep-sea power transmission plan. That’s why subsea cable protection is so important.
Providing that kind of protection has kept PMI in business for more than four decades, engineering rugged, durable ocean hardware for companies and projects around the globe.
Our deep ocean engineering experience helps enable the world-changing potential of renewable power. No matter how breathtaking the advances in technology, if the power has to be sent through subsea cables, those cables need extra protection that our ocean hardware provides.