Tidal energy: clean power generation at the next site

When Christopher R. Sol stood before the swirling waters of the Western Channel, describing his company's vision for alternative energy, he did not face clusters of wind turbines or large numbers of solar cells.

In fact, Sol didn't even see what could stop his dream of Canada on the other side of the strait. If his plan can achieve results, a series of turbines will be put into the bottom of the water in the distance, start running, create electricity, and then connect to the substation on the shore.

His company, Marine Renewable Power, is one of many emerging companies trying to develop tidal energy: water-powered turbines, when the tides rise and fall, rotate under the action of water flow, so that the generators produce electricity. Electricity is clean, and they hope that prices will be reasonable.

Energy company test water tidal power generation

"We will not crack down on the old coal-fired power plants in the Ohio Valley of the United States." Mr. Sol said that he had decades of experience in developing cogeneration power plants and other power projects. "But we will develop new power resources that will be more competitive, including new fossil fuel resources." This is an ambitious goal for the company's CEO and CEO Sol.

The tide is booming and falling twice a day in every part of the world. At a place like Tung Lo, which was once the capital of sardines, located in the Bay of Fundy (the Western Passage is a few deep sea passages around it). At least for the time being, it is most suitable to use tidal power.

The tide is high here, and the water flow is also very strong. The flow of the highest peak four times a day can reach 6 knots, about 7 mph. "We have the best tidal currents on the East Coast of the United States."

Tidal power is not a new idea. Many tidal power stations have already started operations around the world, and one of them is located in France for more than 40 years. But they represent an old way of building a barrage or a dam, blocking the tide. Then the water is released from the turbine. The principle of tidal power generation is the same as that of a traditional hydroelectric power plant.

Even Lian Dongfu himself, in the 1930s, the Franklin D. Roosevelt government had also proposed the construction of a traditional tidal power plant here, only to abandon the plan a year later.

Dam construction is extremely expensive, and it will cause widespread environmental problems. For instance, the East Hao project will cause the two bays to be blocked and change the ecosystem of the area forever. Sol said that the alternative is to put the turbine directly into the water stream, which may be less costly and will not damage the environment.

But no one can fully confirm this, because the way the underwater turbines generate electricity is still in their infancy. In other parts of the world, there are some tidal power projects, such as Northern Ireland, but there are only a few small development projects in the United States, such as the one carried out by Vail Power Company in East River, New York. Its technology is still being tested, and environmental issues have not been thoroughly verified. However, it can be predicted that tidal power plants in Manhattan, Maine, or elsewhere in the United States will become an important input source of electricity in the grid for at least a few years.

The development stage is similar to the current year's wind power

In many respects, tidal power generation is at a similar stage of development as wind power two to three years ago. "When wind power began to develop, it was also a complete small project." Robert Trethier, a researcher at the National Renewable Energy Laboratory in Colorado, said that he studied a discipline called marine fluid dynamics. This all-encompassing vocabulary contains tides, waves, and ocean heat. "They (wind manufacturers) learn how to operate and maintain their machines, to the extent that they are full of failure and trial and error."

Now, huge and efficient wind turbines have appeared on large wind farms in batches. For tidal power generation, Treichell said, "I believe people will see the same situation."

But it may not be such a long time, Tim Ramsay said. A project official from the U.S. energy department said that the department's investment in tidal power projects was just two years ago.

“I don’t think it will take 20 or 30 years for Chaoshan to reach the current level of development of wind power,” Ramsay said. “It may take only 10 years to catch up.” Because computers and other research tools The past is much more advanced, and more accurate software models can simulate the performance and efficiency of the turbine. "Our expectation is that there is enough space to make it not only viable but economical," he said.

Tidal energy researchers learned a lot from the work on wind power. Flowing water is very much like flowing wind, but because the density of water is greater, the same volume of water contains more energy. This gives the tidal power the advantage that wind power does not have, said Paul Jacobson, engineering manager of the Electric Power Research Institute, because its turbine can be built much smaller.

However, in general, the potential amount of wind power development (including solar energy) is much larger than that of tidal energy. A U.S. Institute of Electric Power estimates that in its position of study, including areas with strong tidal waters such as northern Maine, the Pacific Northwest, and Alaska, potentially exploitable tidal energy totals 13 GW (GW, equivalent). 1 billion watts). In comparison, the potential wind power currently available for development in the United States is at least several hundred times higher, and the installed wind capacity alone has reached 35 GW.

However, like offshore wind farms, tidal power plants need to be built near the coastline, and the coastline is close to where people live.

“The cities are generally built on the estuaries of rivers, because in old times, good traffic is possible here,” said Dr. Trichet. The estuaries of rivers and rivers can often provide guaranteed locations for tidal power generation, especially as technological advances can complete more electricity from slower tides.

"Its attraction is not how big it is, but because it is 'zero carbon', it's there," said Dr. Trichet. "You don't need to build power lines."

Like wind power and solar energy, tides are intermittent resources. Even in areas with strong tides, during periods of high tide and low tide, the water flow is sometimes too slow to rotate the turbine.

Sol predicts that in Dongchen, his company's machines will be able to generate electricity for 75% of the time. "It's variable," he said. "It's not a single resource power program."

Wind power and solar energy are also not the same. However, the tide is highly predictable. “We can tell you how much electricity we produce in the next 100 years,” Sol said. “The wind power can't be predicted, nor can it be solar energy.”

This reliability is attractive to grid managers, Jacobson said, "they can use this to increase other power resources and make new plans for it."

The second generation of cross flow equipment research and development

In principle, some tidal energy turbines are similar to wind turbines. For example, the Weir Power Donghe project uses an axial-flow turbine with its axis of rotation in the same direction as the flow of water. Like wind turbines, they look like large propellers. It's just shorter and thicker than wind blades.

In the river between Roosevelt Island and Queens in New York, Vail Power installed test turbines and operated for many years. Recently, the company removed old turbines and started work on the next generation of machines. It has applied for permission from the U.S. Federal Energy Regulatory Commission to open new projects and put 30 new turbines in the river, generating about 1 gigawatt of electricity at its peak.

Trey Taylor, co-founder and company of Vail, said that environmental studies have ended in the summer. "We look forward to obtaining a permit in the near future." But before getting more, the project is hard to make more progress.

In its Alaskan project, Ocean Renewable Power also decided to use different types of turbines and adopt a cross-flow design in which the axis of rotation is oriented perpendicular to the direction of flow. It looks like a working end of a reel mower, but the size is huge. A complete unit will be 20 feet long, with two units on either side of each generator and 250 kilowatts at peak. These units will be installed on the bottom of the base, in some cases can be connected to four units.

The company’s plan is to install a unit in the Western Corridor next year, followed by the installation of more units in the Bay of Ko Posbuk, which is located on the other side of the East Pelican.

However, the company is still testing its turbine and power generation system on a barge berthed in Cobos Book. Turbines with generators with two units can be lowered or raised in water using hydraulic boring machines. Before the turbines had been placed on the bottom of the water, the grey barge had a cabin full of power conditioning devices at the top, which looked like a paddlewheel made by a home-produced paddle wheel.

Environment and cost are the threshold for development

One of the topics about tidal turbines is that they kill or injure the fish that swim through them. Although the results of the study have not yet come out, Sol said that his company's turbine design will rotate relatively slowly, thus minimizing the risk.

Jacobson said that environmental impact assessment will be a "major threshold" for the development of tidal energy systems. "These equipment will be placed in new areas that have not experienced industrial development," he said. "There will therefore be many problems."

Cost is another important point. “Ultimately, we sell electricity to users, and electricity is commodities,” Sol said. “Obviously, our first batch of equipment cannot compete with coal. Our challenge is to produce enough equipment and simplify the manufacturing process. , making the cost more competitive."

Without it, it would be very difficult to complete them. For Sol's companies, other emerging alternative energy sources also find it difficult to raise capital. The company needs to raise funds from 10 million to 12 million US dollars for the continued development of the western channel tidal power generation system and equipment installation.

However, Sol is optimistic that companies can attract different kinds of investors once the equipment starts generating electricity. "They are no longer technical investors, but will be project investors," he said.