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The sea as an energy source of the future? Four questions and answers about electricity from water
By: Sebastian Maks
Wind turbines and solar panels are becoming increasingly profitable alternatives to polluting energy sources such as coal, gas and oil. But the green energy mix still needs to take a big step before it can finally turn its back on fossil fuels. There are now many companies with techniques to generate energy from the sea. How does Maarten Berkhout, co-founder of SeaQurrent and board member of the Dutch Trade Association for Energy from Water, envision the future of water energy? Four questions and answers about this potential but still relatively untapped energy source.

How can you generate energy from water?
In addition to hydroelectric power stations in rivers and dams, fish-friendly variants of which are being developed in the Netherlands by Fish Flow Innovations and Deep Water Energy, there are various ways to generate energy from the sea. Roughly four categories can be distinguished for this: tidal energy, wave energy, osmosis and Ocean Thermal Energy Conversion. Tidal energy generates electricity by using currents in the sea. The sun and moon pull on the seawater, causing currents and creating a continuously changing water level, varying between low tide (ebb) and high tide (tide). This is what SeaQurrent, Berkhout's company, is involved in. SeaQurrent generates energy by placing a type of kite underwater, the TidalKite, which moves because the wings of the kite use energy from the flowing water. In addition to kites, there are also tidal turbines, as it were windmills underwater, such as those developed by Water2Energy and Tocardo.

With wave energy, energy is generated by a continuously varying difference in water level, which is caused by the swell of waves. In the Netherlands, Weco, Slowmill, Teamwork Technology and Wavehexapod specialize in this. Within wave energy, there are all kinds of ways to generate energy, Berkhout explains. “Some use a floating device on the waves, attached to a bottom anchor. The waves create a force between these elements from which electricity can be produced. Others use a pole or wind turbine instead of the bottom, or a breakwater on a dike. And you also have 'osciliating water columns', which use air that is pushed up by the waves.”
Osmosis uses the difference in salinity between fresh and salt water. This technique allows fresh and salt water to flow past membranes, which selectively allow particles to pass through. This creates a positive and negative side, comparable to a battery. In the Netherlands, the company Redstack is working on generating energy through osmosis.

Finally, Ocean Thermal Energy Conversion is a method that generates energy through the difference in temperature between warm surface water and cooler seawater at depth. But, Berkhout indicates, this technique cannot be applied close to the Netherlands. The temperature differences are often not large enough and the required depth is lacking.

Why do we need energy from water?
Moving away from burning fossil fuels requires a fully sustainable energy production system. Significant steps are already being taken worldwide with wind and solar energy, but this cannot generate sufficient energy at all times of the day and year. In addition to energy from wind and sun, other forms of sustainable energy generation are therefore needed. Energy from water is a suitable candidate, because water is always in motion. Power can then be supplied immediately, even when the sun is not shining and the wind is not blowing.
Berkhout explains that, a posteriori, we might have had to organize our sustainable energy network differently from the start. “We once started with the question: it doesn't matter how or where, but can anyone create sustainable energy,” he says jokingly. “That demand ultimately led to solar panels on roofs and wind energy at sea and on land. But looking back, we could also have said: in 2050 we want 100 percent sustainable energy, by which time we expect a certain demand from consumers, a little more during the day and in winter, a little less at night and in the summer - who can supply that profile of energy? In that case, we would have looked much more at a mix of multiple solutions from the start of the energy transition. It is of course possible with solar and wind energy, but you also need a lot of storage. This is much less the case with tidal energy, for example. You can then immediately supply that energy.”
Is it expensive to generate energy from water?
That question can be answered in different ways. Typically, to compare the costs of energy sources, the Levilated Cost of Energy (LCoE) is used. That measure is calculated by dividing the total cost of an energy source by the amount of energy produced, both over the entire lifespan of the source. Looking purely at the LCoE: yes, energy from water is currently an expensive technology, compared to, for example, wind and solar energy. This is partly because wind turbines and solar panels have been in development for a long time and a lot of subsidies have been spent on scaling up these techniques, making them much more cost-efficient. “The LCoE of energy from water is higher because the technology is at the beginning of the learning curve,” Berkhout explains. “Comparable to windmills in the 1970s. At that time, the potential of wind turbines was still very small.”

But Berkhout thinks looking at the LCoE in isolation is too superficial. “The LCoE purely looks at the energy yield, the number of kilowatt hours. But at what point do you get that energy? The costs of energy generation may be cheap, but what additional resources are needed to ensure that energy production meets demand? For example, if you were to do everything based on solar energy, you would have to install large-scale energy storage. That costs a lot of money. That is why we advocate at least a comparison based on the value-adjusted LCoE. If you take all those other costs into account, it becomes a completely different story.”

Berkhout would like to look even more broadly at what it can deliver economically for the Netherlands. If projects are rolled out domestically to generate energy from water, this will create sustainable jobs for residents and can create an economic snowball effect. You could compare that with the import of solar panels from China, where these types of effects occur less often.
How does the Dutch government view energy from water?
It can be said that to date, not much has been done by Dutch governments on energy from water. As mentioned, the focus is mainly on the LCoE, and on that basis water energy does not yet come out well. That was also the reason that in 2021, then minister Bas van 't Wout (Economic Affairs and Climate) saw no reason to change existing, cautious cabinet policy. “Reconsideration of existing national policy, or increasing the national commitment to energy from water, [is] not desirable at this time,” he wrote to the House of Representatives at the time.

“The government focuses on mass and cost-effectiveness,” Berkhout explains. “These are the two pillars for the energy transition. The Dutch Trade Association for Energy from Water is also trying to achieve security of supply. But the challenge is that this makes it more complicated. It quickly becomes very complex to calculate the entire system, and many assumptions are also required. That seems to be the reason why many people say: we can no longer oversee that.”

Yet Berkhout is convinced that energy from water should definitely be added to the future energy mix. The fossil energy mix has also diversified with coal, oil and gas - this should be no different with sustainable energy sources.
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  • Munene Mugambi

    35 w

    The sea is a vast array of untapped resources from energy to food and wildlife. We can get so much from blue economy

    • Rukia Ahmed Abdi

      35 w

      The exploration of energy generation from water presents a promising avenue in our transition to cleaner energy sources. While it's still relatively early in development, the continuous motion of water makes it a dependable source of power, particularly when wind and solar energy may not suffice. Although it might appear costly when compared solely by the Levitated Cost of Energy (LCoE), a more comprehensive assessment considering factors like energy availability and economic benefits to local communities can offer a more favorable perspective.

      • Rotich Kim

        35 w

        Wisdom we need to put into consideration that

        • mercy nduta

          35 w


          • Annett Michuki..

            35 w


            Welcome, let's solve the climate crisis together
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