People have been using tides to run mills for over 1,000 years – way before we had electricity. The question is: Can this old idea help solve our modern energy problems? In this article, we'll dig into how tidal power works, what's good and bad about it, and whether it beats solar energy.
Key takeaways
The moon pulls on our oceans with gravity. When the tide comes in, lots of water rushes toward shore. When it goes out, all that water flows back to sea. Tidal energy uses the rise and fall of tides to make electricity. Engineers put turbines resembling underwater windmills where the water flows strongest to capture power. As water rushes past, it spins the turbines, creating electricity.
There are three main ways to catch tidal power. Each one works differently and has its own pros and cons.
These look like wind turbines but work underwater. They sit on the ocean floor where tidal currents flow fastest. As water flows past, it spins the blades. The spinning makes electricity that travels to shore through underwater cables. You can't see these from the beach because they're completely underwater. Fish can swim around them, and boats can sail over them. It's like a wind farm but invisible.
These are dams built across bays or river mouths. When the tide comes in, water gets trapped behind the dam. When the tide goes out, the trapped water flows through turbines in the dam, making electricity. These make lots of power but they're huge construction projects and can change how the local environment works, which worries eco activists.
These are newer and work like a fence with holes in it. The fence goes across a channel where tides flow. Water flows through holes in the fence, spinning turbines as it goes. This design lets fish and boats pass through while still catching tidal energy. It's a compromise between the other two methods.
Tidal power has some big advantages over other types of energy. Let's look at what makes tidal energy special and how it could benefit us in the long run.
France built the world's first tidal power station at La Rance in 1966, and it's still running strong nearly 60 years later. It took about 20 years to pay for itself, but since then it has generated over £3.3 billion worth of electricity.
Tidal systems cost a lot to build, but they last much longer than other power sources. Solar panels typically work for 20-25 years. Wind turbines last about the same. But tidal systems can run for 75-100 years with basic maintenance.
For regions that build tidal power, this could mean decades of cheap electricity once the initial costs are paid off. Your great-grandkids might still be getting cheap power from tidal systems built today.
The great thing about tides is you can set your watch by them. Solar panels don't work at night or work poorly on cloudy days. Wind turbines sit still when the air is calm. But tides follow a schedule you can predict years ahead.
This reliability is gold for electric companies. They know exactly how much power they'll get and when. No surprises, no scrambling to find backup power when the wind stops blowing. For you, this means more stable electric bills. When power companies can count on steady electricity from tides, they don't need as many expensive backup systems. That saves money they can pass on to customers.
Water is much heavier than air – about 800 times heavier. This means tidal turbines pack way more punch than wind turbines the same size. A tidal turbine the size of a wind turbine can make much more electricity.
This matters because you can get lots of power from a smaller area. One good tidal site can power thousands of homes. That's efficient use of space and materials. For coastal communities, this could mean getting most of their power from one nearby tidal farm instead of distant power plants. Shorter power lines mean lower costs and fewer outages during storms.
Tidal energy makes zero pollution. No smoke, no carbon dioxide, no toxic waste. It just uses the natural movement of water to make electricity. Unlike coal or gas plants, tidal systems don't burn anything. They don't need fuel deliveries. They just sit there quietly making clean power day after day.
For homeowners who care about the environment, this is huge. Plus, tidal energy will never run out. As long as the moon orbits Earth, we'll have tides. That means energy security for your kids and grandkids.
Tidal energy isn't perfect. It has some real problems that explain why you don't see tidal farms everywhere yet. Here are the main disadvantages tidal energy faces today.
South Korea built the world's largest tidal power station at Sihwa Lake for $560 million in 2011 for 254 megawatts of capacity. That's more than $2 million per megawatt – roughly double the cost of offshore wind farms.
Building tidal systems costs a fortune. We're talking billions of dollars for big projects. Why so expensive? Everything has to work underwater in saltwater, which eats metal. The equipment has to handle storms, waves, and strong currents. You need special ships and divers for construction. All of this costs way more than building on land.
For homeowners, this means tidal energy won't immediately lower your electric bill. Electric companies have to pay back these huge construction costs first. But like other technologies, costs should come down as more tidal systems get built.
In the US, the best spots are places like the Bay of Fundy between Maine and Canada, Puget Sound in Washington, and parts of Alaska. Most of the Atlantic and Pacific coasts don't have strong enough tides.
Tidal energy only works in places with strong tides. You can't just build it anywhere along the coast. You need specific conditions: narrow channels, bays, or areas where tides are especially powerful.
This limits where tidal energy can help. If you live in Florida or California, tidal power probably won't directly benefit your area. But good tidal sites could still send power to other regions through the electric grid.
Tidal energy has a rhythm, but it's not constant. Power peaks twice a day during high and low tides. But during the in-between times, there's not much power generated.
This creates a challenge for electric companies. They need to balance this up-and-down power output with other sources or batteries. It's like having a worker who's super productive two times a day but takes breaks in between. So electric companies might use tidal power when it's available and switch to other sources during slack tides.
Big tidal projects can affect ocean life. They might change how water flows, block fish migration routes, or alter the local environment. This is especially true for large tidal dams that can completely change how a bay or estuary works.
Environmental groups often oppose big tidal projects, which can delay construction for years. This adds costs and uncertainty to tidal development. The good news is that newer tidal technologies are designed to be less disruptive. Underwater turbines, for example, can coexist better with marine life than large dams.
Read also
If you're thinking about renewable energy, you've probably considered solar panels for your roof. How does tidal energy compare to solar? While you can't install tidal turbines at home, understanding the differences helps you see the bigger picture of clean energy.
You can get solar panels installed on your house today for about $15,000-$25,000 before tax credits. They start saving money right away and usually pay for themselves in 6-10 years.
Tidal energy requires massive investments that only big companies or governments can afford. You can't install it yourself, and projects take years to plan and build. But here's the thing: if your area gets tidal power, you could save money without spending anything upfront. Cheap tidal electricity could lower everyone's electric bills in the region.
Solar wins for immediate options. You can put panels on almost any roof, and solar farms can be built quickly in most sunny locations. This flexibility has made solar the fastest-growing energy source worldwide.
Tidal energy is limited to specific coastal areas and takes longer to develop. But once built, tidal systems last much longer than solar panels and need less maintenance.
Solar panels produce about 15-25% of their maximum possible power over a full year. That sounds good, but remember they only work during daylight hours and need clear skies for peak performance.
Tidal systems do about 25-30% of their maximum. That's actually pretty good considering they work 24/7. The difference is reliability - tidal systems produce steady power following the tide schedule, while solar panels might make great power one day and just a little bit the next if it's cloudy.
Solar energy's biggest weakness is weather. Clouds, storms, and short winter days all reduce power output. Even in sunny places like Arizona, solar panels sometimes produce very little power. Homeowners with solar panels often need batteries or stay connected to the electric grid for backup power. This adds cost and complexity.
Tidal energy follows a predictable schedule. Electric companies know exactly when tidal turbines will produce power for decades ahead. This makes it easier to plan and reduces the need for backup systems.
For homeowners, it's not really a choice between solar and tidal. You might install solar panels today for immediate savings while supporting tidal development through your electric company for long-term benefits. Both technologies can work together to create cheaper, cleaner electricity for everyone.
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Sergey has been running A1 SolarStore since 2017 with the main idea in mind – making going solar easier for everyone. Based on a thorough market research and his personal experience, he shares his ideas on both solar industry and management related topics
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