Marine energy is renewable and generally predictable. It could thus compensate for the unplanned intermittency of solar and wind generation, its proponents argue. But several challenges still need to be overcome for the energy to become widely used.

The previous year marked quite an important milestone in Europe. For the first time, according to this report published by the think-tank Ember, wind and solar power surpassed fossil fuels in the EU’s electricity mix. The European Electricity Review analyzes full-year electricity generation and demand data for 2025 in all the EU 27 countries to understand the region’s progress in transitioning from fossil fuels to clean electricity. It is the tenth annual report on the EU power sector published by Ember.

The report found that electricity generated by wind turbines and solar panels accounted for 30% of EU power production in 2025, exceeding the 29% produced by coal, oil and gas-fired power plants. Solar energy generation was particularly high: it reached a record 369 TWh in 2025, says the report, 20% more than the previous year.

But while several experts point to a tipping point, the challenges of accommodating intermittent sources of energy like solar and wind in the power grid remain. Energy storage using large lithium battery packs and pumped hydro are the two favoured options by utilities around the world. ( For more on the topic of batteries for energy storage, read : The pros and cons of batteries for energy storage | IEC e-tech).

Other solutions are emerging, though, which their proponents argue are cheaper and/or cleaner. One of them is marine energy generation. The energy that comes from the sea and rivers is very diverse and totally renewable. Still massively untapped, the potential for harnessing power from the ocean and rivers is huge.

Different types of marine energy

One of the ways of converting the energy of the ocean into electric power is by using tidal energy. Tidal turbines generate electricity from the tides caused by the gravitational force of the moon. They can be mounted to the seabed or floated like a tethered submarine with turbines (tidal stream), or integrated within a barrier on a lagoon (tidal range). Like other forms of marine power, tidal energy is renewable and also predictable (unlike solar and wind energy). Although tides change regularly depending on the time of day, they follow a consistent pattern and can be accurately forecasted. “You can predict in a hundred years-time when you will have an energy peak!,”  IEC expert Peter Scheijgrond enthuses.

At his company Bluespring, Peter Scheijgrond and his team build public-private partnerships to help technology developers, research institutes and governments get their ocean renewable energy projects financed and implemented, with a focus on demonstration at sea.

Other marine energies include ocean thermal energy, salinity gradient energy, and wave energy. Ocean thermal conversion exploits the difference in temperature between deep and surface waters, and is being tested notably near the Indian coast,  while salinity gradient generation converts the difference in salt concentration between fresh and salt water. Wave energy converters capture energy from the motion of waves through either floating or submerged devices.

Tidal energy is the most promising for now

Several experimental marine energy projects exist around the world using one or the other forms of generation. But tidal energy is viewed by experts in the field as the form of marine energy which is the most likely to move rapidly into the commercial space. “Of the different types of marine energy, tidal is the closest to farm-scale projects. A tidal stream project from Proteus with four turbines on the seabed of the Pentland Firth in the north of Scotland has been producing grid power for over seven years now.  Another very promising project is the latest announcement of funding for several tidal farms at Morlais, in a sea area near the coast of North Wales. These will be the first commercial tidal farms from 2028 onwards,” Peter Scheijgrond describes.

Marine technology has been slow to develop into an industry because of its initial high installation costs and the problems due to generating energy in rough environmental conditions.  Convincing regulators to come on board has also been a struggle. As Peter Scheigrond explains, “Getting regulators to understand the technology is our main challenge. It can take a very long time to get the permits to go ahead and build marine energy systems. Most of the time, regulators don’t know the difference between wave and tidal energy. We still have a lot of awareness-building to do. “

Marine energy can compensate for fluctuations

But for Scheijgrond, one of the overlooked advantages of marine energy is that it can provide a renewable form of energy  to compensate for the intermittency of wind and solar PV. “We see the limitations of solar photovoltaic (PV) and wind power. These energies cause net congestion and variability in the electricity supply during the day but also the seasons. Their market value also varies hugely, and there is a need for complementary sources of electricity that can be produced at times when solar PV and wind are not generating enough. We also need a solution which is cheaper and cleaner than large battery systems for energy storage. Marine energy can play an important role in this context, as it offers a predictable renewable resource that can add value to the energy system by generating power when other renewable sources are less available.”

There are many different market demands for marine energy, according to Scheijgrond. “Developers see many end uses for marine energy technology, some of which are niche markets. For example, there is a demand for small autonomous power applications at sea to power remote sensing. All you need for that is a very small wave power buoy that can monitor its surroundings 24/7. The price point (or levelized cost of energy) for that “service” is much less relevant than for grid power applications. The next niche market could be island and coastal communities, which have a high cost of energy. Many of these remote communities are not well suited for large-scale wind farms. Solar PV can be part of the solution, but it does not generate power at night and typically requires large areas of open, unobstructed land. Marine energy can be used in a hybrid form, combined with solar PV and batteries, to power a microgrid,” he says.

Other demands include, in his words, “large-scale deployments, like the Welsh tidal project I mentioned, which will feed power directly to the grid. There is another similar deployment near Brittany in France in the Raz Blanchard. Both France and the UK accept a higher price point because they have a strategy for building a marine energy industry. In the longer term, I foresee a fully integrated offshore energy system combining wind, wave and offshore solar. Because these resources peak at different times, they can complement each other and help balance daily and seasonal variations in power generation. Excess electricity can be used to produce green hydrogen,” he adds.

Standards and certification essential for an emerging industry

Whatever the future deployments of marine energy projects, they require standards and testing/certification to make the shift to commercial use, which is what the IEC offers.

An IEC technical committee, TC 114, has been specifically set up to develop marine energy conversion standards. It has produced many first editions of technical specifications. According to Scheijgrond, “These technical specifications provide a structured framework that helps guide the development and testing of emerging marine energy technologies. At the same time, applying them in real-world demonstration projects allows us to gather practical experience that can be fed back into the ongoing work of the maintenance teams and ad hoc groups responsible for developing the second and third editions of these standards.”

But third party independent testing and certification is just as crucial, he argues. “We want marine technology and marine energy to be successful – that’s what we are planning for. And for that to happen, we need an independent third party certification framework. Without that, projects will have problems becoming bankable. You need a stamp of approval to ensure the product is validated, verified and safe, notably for the environment, and will perform as it is expected to. Agnostic investors or insurers need that stamp of approval before they act. They will take the financial risk on board but need reassurance about the technology, that it will work for 15 years and will produce what it says on the box. Large-scale roll-outs require investments of hundreds of millions of dollars, and generally investors are not technology specialists; they rely on certification to ensure that the systems they finance will operate safely, predictably and over the long term. And that is where the IEC System for Certification to Standards Relating to Equipment for Use in Renewable Energy Applications, IECRE, comes in,” he concludes.

Betting on the potential of marine energy seems increasingly likely to pay dividends for those involved.

Author: Catherine Bischofberger

The International Electrotechnical Commission (IEC) is a global, not-for-profit membership organization that brings together 174 countries and coordinates the work of 30.000 experts globally. IEC International Standards and conformity assessment underpin international trade in electrical and electronic goods. They facilitate electricity access and verify the safety, performance and interoperability of electric and electronic devices and systems, including for example, consumer devices such as mobile phones or refrigerators, office and medical equipment, information technology, electricity generation, and much more.

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