Renewable energy means harvesting electricity (and sometimes heat) from natural resources – wind, sunlight, flowing water, or heat from the Earth beneath its surface. All of these sources are free and will last almost forever.

Yes, we hear the gossip of negativism in the audience. “One day the sun will explode and where will your renewable energy come from? Well, we say to you, “Sure, one day the sun will explode and consume our tiny heavenly lifeboat.” The difference is that it won’t happen for a few billion years, whereas if we don’t solve the climate crisis in the next 8 years, humanity will be screwed in six ways until Sunday in a century or so. of them.

Tides are a renewable energy source that we rarely talk about. Think about the extent of the oceans. Now imagine how much energy it takes for those trillions of gallons of seawater to splash about twice a day. If we can’t figure out such a huge number, we can turn to the people at Encyclopedia Britannica for help. The answer? 3,000 gigawatts or 3 terawatts. That’s over 1,000 terawatts per year, which is a lot of energy to harness.

Harnessing the tides is difficult

Recovering some of this energy is difficult. According to Washington post, a number of techniques have been tried, including underwater kites, but none of them have been commercially viable. Many companies have tried and gone bankrupt. The European Marine Energy Center is planning a new attempt in the Orkney Islands, which are home to some of the most powerful tides in the world.

Neil Kermode, managing director of EMEC, said tidal power is poised to help Britain deliver on its pledge to cut carbon emissions to zero. “R&D has shown it works and industry has shown it can do it,” he wrote in a call for electricity regulators to adapt to new technologies like ocean energy. “This opportunity is right here now.”

The O2 Orbital

There are currently 3 tidal power devices in the Orkney Islands, but the most ambitious of them is Orbital Marine’s Orbital O2, which has a power of 2 megawatts – enough to heat the tea kettles and run the tea kettles. lights in 2000 in the UK. outbreaks per year. What is Orbital’s plan? The Washington post describes it this way: “Imagine taking an offshore wind turbine, with its rotor blades turned by moving the air, and turning the thing over, plunging it into the sea and letting the tidal currents spin the blades. “

The Orbital O2 is 240 feet long, weighs 650 tons, and is as big as a floating jumbo jet. “The thing looks like the Beatles yellow submarine,” says the Washington post. It has a large impeller with 64-foot-long blades mounted on each of its wings, which when deployed are as long as those of a 747. Once anchored in place, the wings pivot toward the bottom of the wing. ocean where the tidal current spins the turbines to generate electricity. Some of this electricity is stored in batteries on board, but most of it is sent via a submarine cable to a coast station connected to the electricity grid.

One of the advantages of the Orbital O2 design is that the wings can be raised as needed to allow maintenance tasks to be performed at sea level rather than underwater, which can significantly reduce the cost of operation. turbines. Another is that the turbine blades can be reoriented to take advantage of the tidal flow in either direction.

Oliver Wragg, Commercial Director at Orbital, knows that there have been many successive ocean energy experiments. He pointed out to Washington post that the O2 is more than a prototype. “It is designed to generate electricity for use,” and to power the national grid and land experiments for green hydrogen production. The O2 is designed to stay in the water for a period of 15 years, he said.

Wragg would love to see hundreds of devices clustered in the seaway, just as offshore wind farms are today. He says the global tidal power market today is 100,000 megawatts, enough to provide electricity to 100 million homes. To build and maintain 50,000 machines generating 2 megawatts would cost 150 billion dollars, he says. But those costs could drop dramatically once a few hundred machines are built and the economies of scale start to kick in.

You skeptics, keep in mind that solar panels were once prohibitively expensive, and LED lights were originally so dim that no one thought they would find their way into commercial production. Never say never, in other words. Renewable energy technology is still in its infancy and huge efficiency gains and cost reductions are still possible.

Gareth Davies, chairman of the Aquatera group in Orkney, said he met Prime Minister Boris Johnson last year and told the Prime Minister that 25% of Britain’s total electricity could be supplied by the abundant wind, tidal and solar resources of northern Scotland if properly harnessed. Today, less than 1% of the potential is exploited.

Marine energy around the world

Tidal power may be little more than a curiosity today, but it could become an important part of the world’s energy future. Orbital O2 isn’t the only one harnessing the power of the tides. Other tidal machines are in service along the coasts of China, France, South Korea and Nova Scotia. In the United States, there are demonstration projects in Maine and Washington State. There’s even one in the East River in New York.

One of the largest tidal power facilities in the world is the MeyGen Tidal Current Project in the waters off the north coast of Scotland. In 2019, this facility supplied 13.8 gigawatt hours of electricity to the UK grid. It is owned and operated by Simec Atlantis Energy and consists of four 1.5 megawatt turbines. In the next phase of development, 49 additional turbines with a total capacity of 73.5 MW are planned.

“The project… will provide an investment opportunity for providers of commercial debt and equity capital to invest in tidal stream projects,” the company said. “In addition, Phase 1C will create around 5,300 full-time positions, reallocating jobs in the oil and gas sector and placing Scotland at the forefront of a world export market estimated at 25 GW for decades. to come, while drastically reducing the LCOE.

Don’t be surprised if ocean energy becomes a major source of renewable energy in the years and decades to come, provided the sun doesn’t first erupt in a final cataclysmic fusion. If that happens, talking about renewable energy will largely become irrelevant.

Hats off from CleanTechnica to Ken Anderson.

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