(The video above is a news clip from CBC News Nova Scotia, and the related article, published on Nov 22, 2016. It offers a bit of recent history of previous progress, and hopes for the project). 

OpenHydro Group goes into liquidation

This article gives an overview of this important news and then goes on to explore the pros and cons of tidal energy overall.

Businesses in all industries can fail, so this isn’t necessarily a blight on the tidal power industry itself. The news that Ireland’s OpenHydro Group Ltd. has filed for liquidation has created some bad headlines for alternative energy. OpenHydro has been developing an underwater tidal turbine project where huge (five-stories in height) turbines are fixed to the seabed.

The ongoing project has been developing offshore in Nova Scotia, Canada. The company filed for liquidation last July. New businesses and projects have a development runway and usually a tight schedule. In what is the worst timing imaginable, OpenHydro went into liquidation only two days after the first turbine was turned on. Right now, it’s spinning with the tides, but not sending any electricity to the grid.

Another turbine is stuck on a barge, for legal reasons unable to go anywhere. The reason for the bad timing was that the French parent company, (Naval Energies), announced that it wouldn’t fund any more tidal power projects. France is one of the most bullish countries when it comes to alternative energy. To pull funding when the project seemed to be going so well is a bad omen. Are underwater tidal turbines ever going to be cost-effective?

A perfect spot for an underwater turbine

The Bay of Fundy is an ideal spot for tidal power, here’s a quote from the Parks Canada website:

Every 27 and a half days, when the moon reaches a point in its orbit closest to the earth (called perigee) the tidal range is increased. When perigean tides coincide with spring tides, extreme tides can be expected. In the Bay of Fundy, these conditions may create tides as large as 16 metres (53 feet).

16 metres is enormous, no wonder they had some problems with prototypes coping with the power. Do we have to ask though, if Naval Energies have ceased funding for a project in an ideal place in the world, where does that leave the marine turbine industry?

Subsidies in the solar power industry have made sense. The technology has improved by leaps and bounds. Photovoltaic panels have kept falling in price at a rate that no-one expected. Can tidal offer the same efficiencies over time? It seems unlikely, and Naval Energies won’t have decided to pull the plug lightly.

The creditor list runs to CAD 2.6 million and the authorities are holding the Canadian assets of the OpenHydro local subsidiary. Staff in Dublin have weeks to find new investors to keep the project alive.

Michael Murphy,  the group’s Dublin lawyer, said:

They’re very passionate about the technology,” … “They believe it works and they are very keen that it will continue to be associated with Ireland and that we would maintain an operating base here.”

Let’s hope that the project is reinstated, either by OpenHydro or by whoever buys the assets. Having this turbine at the bottom of the ocean rusting away would be a massive own goal for the tidal power industry.

What is tidal energy?

In a literal sense, it’s the kinetic energy of the movement of the oceans as a result of tides. The world’s oceans move higher and lower in relation to ground level. This happens roughly twice a day (24 hrs, 50 mins and two high tides and two low tides) due to the interaction of magnetic, gravitational forces with the moon and sun.

When the magnetic forces between the Earth and Moon line up then the oceans rise at the closest point between them. When the angles change then, they fall back to where they were. When the Sun, Moon and Earth line up, we get even bigger tidal movements called spring tides.

These tidal movements represent an abundant source of kinetic energy, one that can be captured and turned into electricity. Huge, submerged turbines can achieve this and contribute to the local power grid.

At the moment, we can find undersea turbines, like wind turbines but much larger and in an enclosed design that protects the blades. Also, tidal dams exist, that operate just like other hydroelectric dams.

How does tidal energy work?

Turbines are giant dynamos, where kinetic energy turns rotor blades, which spins a generator that creates electricity. If you remember your high school science lessons, you probably made a basic dynamo with coiled wire and magnets. To simplify the concept further, tidal turbines and wind turbines do the same thing. One converts wind, and the other tidal forces, both turbines create electricity.

Tidal energy pros and cons

Just as with all types of energy, there are advantages and disadvantages. There’s a tendency to use simplistic thinking such as green=good or fossil=bad, but the reality is far more complicated. As well as the practical point that fossil fuel will take a long time to be replaced, all renewables have disadvantages too, some environmental.

For example, wind turbines kill a lot of birds, including some protected species. Solar cells use rare earth materials that are responsible for a lot of pollution and poisoning of water supplies during the mining process. The next two sections in this article will focus on the tidal energy pros and cons.

Advantages of Tidal energy

• The source is natural and renewable without mining or fuel input from us. We will get tides as long as the Moon, Sun and Earth are around, and behaving the way that they have done for billions of years.
• No carbon, methane or any other greenhouse gases are released into the atmosphere as a result of the creation of tidal energy.
• It’s non-polluting, meaning that there’s next to no likelihood of significant spills, leaks or toxins entering the water supplies or food chain.
• Tides happen twice a day, every day, so the energy is predictable. We even know in advance what time and height flows will be a long time in advance. Tidal power has that advantage over randomly intermittent energy supplies such as solar and wind.
• Tidal energy is cheap to run and operate once installed. This is in contrast to the ongoing need to mine fossil fuels. Nuclear power requires a lot of operating expense in comparison, not to mention the nuclear waste that can’t be disposed of, only stored.
• An advantage of underwater tidal turbines over hydroelectric dams is that they don’t block off the whole river or estuary. Dams cause issues with migratory salmon and sea trout populations.
• Tidal energy and hydroelectric energy, in general, is useful at slow speeds (flow rates) of even 1 metre per second. Unlike wind, where there has to be a strong airflow even to move the rotor blades.
• Despite the harsh effects of saltwater, with monitoring and servicing the hardware lasts really well. The tidal barrage power plant across the La Rance estuary in Brittany, France was built in 1966 and is still going strong.
• A tidal barrage can double as a bridge and a storm surge barrier.

Disadvantages of tidal energy

• Due to the spinning of the earth on its axis, there is little tidal movement closer to the equator. Substantial tidal variations equal a lot of power, and minor moves mean that turbines won’t be cost effective.
• Reliable tidal movementsalso highlight a disadvantage. We know that during a few hours either side of a high or low tide, the flow stops. In fact, turbines won’t turn for 10 hours per day, which is 40% of a day, week, month or year.
• Tidal barrages completely change the flow and levels of an estuary, in a similar way to a dam. The local ecosystem changes and that affects wildlife and flora. Any blockage also adds to siltation and might increase the chances of flooding upstream.
• As with all new technologies, equipment is expensive and tidal power isn’t cost effective in comparison to traditional energy production. Some parts need to be custom made, and there are no economies of scale, or new efficiencies discovered like in mature tech markets.
• The ideal placements are limited. With current technology, a tidal range of at least seven metres is required, which isn’t common. Unlike wind farms, tidal turbines get installed close to land, and there aren’t many places with a strong enough tide. Considering that there are current cost inefficiencies, a stronger flow compensates and generates more electricity. A perfect example of a right place is the Bay of Fundy which has one of the strongest tidal currents in the world. As was shown in the video above, sometimes equipment gets wrecked by the power of the ocean.
• The underwater turbines like the ones created for the Nova Scotia OpenHydro project are underwater. Over time, will they get snagged by fishermen, dredgers, or submerged wood and debris? In areas with vast differences in the low and high tide, might they make contact with large boats at low tide?
• Wind power kills birds, what about seals, dolphins and whales? As well as crustaceans, jellyfish and all manner of sea life? Any protective netting or mesh would get filled with plastic bags and other blockages.
• Barrages decrease salinity and block fish from travelling up and downstream. They also remove mud flats for birds by raising water levels overall.
• Breakdowns of an underwater turbine will be awkward and costly to address in comparison the solar or wind power. The harsh environment and saltwater are more likely to affect the equipment over time.