New Technologies Capturing Untapped Energy Source
Harnessing the clean energy of the oceans’ constant motion has long been the dream of environmental scientists and engineers. Other clean energy sources, like solar and wind power, have their advantages but lack reliability and predictability. In contrast, the oceans’ tides reoccur twice daily on a constant and predictable schedule.
Ocean tides are caused when the moon, and to a lesser extent, the sun, exert gravitational forces on the Earth. When the highest point in the tidal wave reaches a coast, it experiences a high tide. When the lowest point, or trough, reaches a coast, it experiences a low tide. The two primary methods of generating electricity from tides are (1) “tidal range” devices that utilize the difference in water levels between high and low tides and (2) “tidal stream” devices that capture energy from flowing water in tidal currents.
Industry Started in 1960s
The history of tidal energy goes back decades. The first tidal range energy plant is La Rance, on the estuary of the Rance River in Brittany, France. Built in 1966, it still operates today and produces energy for a city of 250,000.
Four other similar plants exist around the world in South Korea, Russia, China, and Canada.
Today, the industry is focused on developing tidal stream technology. The first multi-device pilot farms were installed in 2016. MeyGen is the world’s largest planned tidal farm, located in the Inner Sound of the Pentland Firth, Scotland, and currently powered by four turbines developed by Andritz Hydro Hammerfest and SIMEC Atlantis Energy. The total capacity of the project is planned to be 398MW through three development phases.
The first three turbines of Nova Innovation’s Shetland Tidal Array, Shetland, UK, were deployed in 2016, followed by a fourth one in 2020. In January this year, the array was completed with two more turbines, making it largest in the world.
An Untapped Resource
The US Department of Energy (DoE) estimates that developing just 5% of tidal energy’s resource potential from the US’ thousands of miles of coastline would generate 12.5 terawatt-hours of electricity per year.
In New Jersey, for instance, state lawmakers have been considering ways to fund regional tidal power projects. Tidal energy is seen as a way to help this coastal state reach its ambitious goal of providing 100% clean energy by 2050, and at least 50% of its electricity from renewables by 2030.
However, although the oceans offer much from a green energy perspective, according to the International Energy Agency’s (IEA) Ocean Tracking Report, ocean power technologies are below the growth rates needed to reach net-zero emissions by 2050.
Power Technology reports, that according to the IEA, “demonstration and small commercial marine projects remain expensive because the economies of scale necessary for significant cost reductions have not yet been realized.”
Marine power’s status remains “not on track” with the projected sustained annual growth of 33% through 2030. Achieving this level of growth generation “would require an average 1GW of capacity additions annually until 2030,” which is far from guaranteed at the current growth rate level, Power Technology says.
Some experts estimate the potential energy from tidal movements to be “enormous,” with about 1 terawatt of power stored in the world’s oceans.
There is strong belief, though, in the power of the tides to provide significant amounts of renewable energy.
To date, solar and wind energy technologies have received the most attention from regulators and industries, according to a report, “Challenges and Promise of Tidal Energy,” by the Parker Hannifin Corporation, a US-headquartered engineering company.
Nevertheless, some experts estimate the potential energy from tidal movements to be “enormous,” with about 1 terawatt of power stored in the world’s oceans. “This would be enough to power 10 billion 100-watt lightbulbs at once,” the report says.
Because tidal energy is still an emerging innovative technology, relying only on the market to deploy new projects is difficult. To reach higher levels of deployment, the tidal energy sector would need the kind of support that wind and solar energy technologies received to reach maturity.
In return, tidal energy would enable a higher penetration of solar and wind energy, because it would enhance flexibility and security of energy supply to a renewables-based grid.
Obstacles to Expansion
Despite tidal energy being an environmentally friendly and a highly predictable energy source, there are disadvantages.
The biggest barrier to tidal energy is the high cost associated with building tidal power stations.
There are limits to the location of tidal energy plants as they require strong tides. The Parker Hannifin report also cites “aesthetic concerns,” as the plants cannot be too close to urban locations. But most tidal turbines are at the bottom of the ocean, invisible from the surface. Others float on the surface but are often so low that one cannot see them from the shore.
The new tidal energy technologies under development are minimizing the impact of tidal power plants on fish and ocean life, compared with traditional tidal plants now in operation.
Another major concern is potentially negative environmental effects on marine life. “Spinning blades can injure living organisms, as can water fouling resulting from various system components,” warns the Parker Hannifin report. Nevertheless, to date, several fish studies have not observed marine wildlife colliding with turbines or fish being harmed, according to Lotta Pirttimaa, Senior Policy Officer, Ocean Energy Europe.
The new technologies under development are minimizing the impact of tidal power plants on fish and ocean life, compared with traditional tidal plants now in operation.
Nova Scotia’s Floating Tidal Energy Project
One example is the Pempa’q In-stream Tidal Energy Project in the Bay of Fundy—famous for having the highest tides in the world—in Nova Scotia, Canada. The project is expected to deliver up to 9 MWs of electricity to the Nova Scotia grid, powering approximately 3,000 homes, and reducing greenhouse gas emissions by 17,000 tons of carbon dioxide a year.
Sustainable Marine Energy Ltd, the UK-founded provider of coastal and nearshore renewable energy solutions, is working to deliver a floating tidal energy array to the Pempa’q Project, to be delivered in multiple phases. “The firm’s in-stream technology differs from traditional tidal energy systems, including barrages (artificial structures that affect water flow), with the electrical generators installed directly into the tidal stream. This means there is no blockage to the water passage from large structures, greatly reducing impact to the surrounding environment and marine life,” the company claims.
Last year, as part of the first phase of the Pempa’q Project, Sustainable Marine officially powered up its “next generation” floating tidal energy platform. It is deployed at the site of the Fundy Ocean Research Centre for Energy (FORCE). The goal is to test the technology and environmental monitoring systems before placing them in the Minas Passage in the Bay of Fundy.
Floating Hybrid Renewable Energy System in Asia
Meanwhile, in Asia, Keppel Infrastructure, the Singapore-based provider of sustainable water solutions and advanced waste-to-energy technologies, the National University of Singapore, and Nanyang Technological University are developing a “first-of-its-kind” floating hybrid renewable energy system for operation in Singapore. The project, launched in October, uses modular offshore floating solar platforms. These can be used with other renewable energy technologies, such as ocean wave energy conversion systems, tidal energy turbines, and paddles and wind turbines.
A “first-of-its-kind” floating hybrid renewable energy system can be used with other renewable energy technologies, such as ocean wave energy conversion systems, tidal energy turbines, and paddles and wind turbines.
The vision is to design and deploy a pilot system with the capacity to generate at least 100 MW of renewable power. Once successful, this can be scaled up and replicated to other regions.
Ms. Cindy Lim, CEO of Keppel Infrastructure, said, “With limited land space in Singapore, moving into waters offshore presents opportunities to unlock the potential for more diversified renewable energy sources, thereby enhancing energy security and supporting Singapore’s transition to a greener energy mix.”
Elsewhere in Asia, UK-based HydroWing has signed a memorandum of understanding (MoU) with state-owned company Indonesia Power to develop and support tidal energy projects in Indonesia.
HydroWing’s tidal solution includes a multi-rotor turbine design to increase energy availability and lower energy cost. It uses a particular (Tocardo) turbine that has been in continuous operation for the past eight years in the Netherlands as part of the Oosterschelde Tidal Power 2 Project.
Scottish tidal energy developer SIMEC Atlantis Energy made headlines by manufacturing and installing a 500-kW tidal turbine in Japan’s Naru Strait.
Clearly, there is much to be done before ocean tidal energy takes its place alongside other renewables in the global energy mix. However, the increase in the number of projects—and the commitment by renewable energy companies to invest in new technology—suggests that harnessing the energy of the ocean’s tides may not be far way.
*Nnamdi Anyadike is an industry journalist specializing in metals, oil, gas, and renewable energy for over thirty-five years.