After sunshine comes shortage: an overview of the most promising energy storage solutions

The energy transition is in full swing. As the share of renewables in our energy mix continues to increase, so does the need for durable energy storage solutions. In this Insights piece, we’ll look into the current and future situation of energy storage and discuss some of the most promising solutions.

The rise of renewables

Now more than ever before, climate change is forcing us to rethink energy production. Over the past few years, there has been a massive push towards renewable energy, as we attempt to decarbonise our electricity production and switch to green electricity for carbon-intensive activities like driving cars and heating buildings.

At Jan De Nul, we’re doing our part. In addition to installing offshore renewables and creating the necessary interconnections between grids and offshore wind farms, we are also electrifying our entire vehicle fleet and building a brand-new energy-neutral office.

Balancing supply and demand

While renewables represent the foundation of the energy transition, unfortunately we cannot always count on the sun and the wind. And indeed, the more intermittent energy sources we integrate into our energy mix, the greater the need for energy storage. Being able to successfully store solar and wind energy at times when it is abundant means that we will then be able to draw on it in times of scarcity. This will allow us to match supply and demand for green electricity more efficiently and make optimal use of our grid – instead of the current, less efficient peak load capacity system.

To deal with fluctuations in supply, many countries rely on gas-fired power plants, as they can be switched on and off quickly. However, since gas remains a finite energy source, we should regard it as a transition fuel that will facilitate the transition towards the renewable era in the coming decades.

Into the suite of storage solutions

Over the years, a great deal of research has been carried out into energy storage, especially into applications designed to balance the grid. These solutions supply large amounts of energy – preferably over an increased period of time, although this is not a prerequisite for balancing the grid – thus providing a reliable back-up source that will help us to manage periods of energy shortage.

Let’s take a look at a few promising energy storage solutions.

Pumped hydropower

In the case of pumped hydropower, at times of energy abundance, water is pumped into an upper reservoir. When energy becomes scarce, the water falls, causing a turbine to spin and generate energy. A good example of this can be found in the hydroelectric power station at Coo, for which energy company Engie engaged Jan De Nul as the main contractor.

Although pumped hydropower certainly has potential, there are very few suitable locations to build such plants. Moreover, securing the necessary permits is a long drawn out procedure, capex is high, and projects like these often encounter strong protests from environmental action groups.


Recent years have seen impressive technological advances in the field of batteries. What’s more, the cost of producing them has also fallen sharply, mainly due to the success of electric vehicles and mobile applications. However, these batteries are fundamentally very different from those used in large-scale grid applications. Although the lithium-ion batteries used in cars and telephones can deliver considerable amounts of energy in a compact, lightweight form, they can only store energy for a limited time – in other words, compared to alternative types of batteries, they lose energy relatively quickly.

Engineers are therefore working on the development of new types of batteries, whilst at the same time expanding the range of applications. One promising example is the Redox Flow battery. Unlike lithium-ion batteries, Redox Flow batteries have a large set-up, but they lose capacity less quickly. We are currently installing a Redox Flow battery at our site to store the solar energy that is produced on our roof. This means that that we’ll be able to make optimal use of any surplus solar energy for charging our fleet or cooling and heating our offices.

It's important to point out that most research into battery technology is in full stealth mode. We can expect a truly disruptive evolution, and there’s a very strong chance that we won’t see it coming. We’ll probably see very swift progress in this area since there are many different groups of people working on it, from start-ups and funds to academics.


Finally, in addition to traditional solutions, experts in the field of energy storage are also working on several ‘exotic’ solutions. One example is hydrogen, which can be produced when there is an abundance of cheap, renewable energy.

Jan De Nul is gaining first-hand experience of this storage solution with the Terranova project in Zelzate. There, we have remediated and redeveloped a former gypsum landfill site, transforming it into an energy park with installations for solar panels, wind turbines, and a hydrogen production plant.

Other examples of exotics include energy storage in blocks, and heat storage, for example in basalt rock. Although at first glance these exotics all appear to be interesting solutions, it’s important to keep in mind that the low cost of batteries and the availability of materials could eliminate the need for them in an instant. It still remains to be seen whether they will be able to successfully compete with the more traditional solutions mentioned above and conquer the market in years to come.