Flatland hydropower

Despite its limited natural resources, The Netherlands should build innovative hydropower systems, says an expert in the field, Hans van Duivendijk. Such expertise is in worldwide demand.

The inlet of a hydropower plant at full power. (Photo: no credit)
The inlet of a hydropower plant at full power. (Photo: no credit)

Soaring to a maximum of a measly 322 meters above sea level (in Vaalserberg), the Dutch heights are limited at best. Our rivers move slowly through the flat, wide landscape. The waves on our shores are puny and the tide amounts to three meters at most. Still, Dutch engineers have been involved in hydropower projects all over the world. The author of ‘Water Power Systems’, Hans van Duivendijk, says Dutch engineers are in demand because of their broad education and analytical thinking. “Thus far”, he adds, on a cautionary note. 

Van Duivendijk should know. His curriculum vitae reads like an adventure novel, as a Dutch transport minister once remarked. As a student, Van Duivendijk worked on hydropower projects in Austria (1956) and Canada (1957). As an engineer, he supervised the building of a dam in Nigeria, tidal closures in Ghana, flood control studies in Morocco, and the Feni closure dam in Bangladesh (1985). Since 1986, Van Duivendijk has taught Water Power Systems at the faculty of Civil Engineering and Geosciences – a subject he took over from professor Glerum. For four days a week he remained employed by the consultancy firm Royal Haskoning. Last week Thursday, Van Duivendijk (75) retired after more than 20 years at TU Delft and 50 years at Royal Haskoning.

His farewell symposium however was extremely future-orientated, featuring a number of daring water energy projects for the Netherlands and stressing a commitment to generating or storing sustainable energy. Van Duivendijk would like to see all of these projects realised: “It gives you a nice introduction at large hydropower projects abroad.”

Projects proposed at the symposium featured power storage: a prerequisite for sustainable energy. Wind, wave or tidal power is variable and generally will not correspond to the daily rhythms of power usage. Power storage is needed to buffer the imbalance between supply and demand on the power market. It can store windpower as well as excess production from nuclear or coal plants. Pumped hydro (operating a hydro power installation in reverse) is a proven method for such storage, with an efficiency of about 80 percent. In England, for instance, a 1,700 megawatt pumped hydro installation is used to stabilise the grid when the nation, en masse, ‘puts the kettle on’ at the end of a popular TV-series. The amount of energy stored is proportional to the product of the height difference and the water quantity involved.

Waldo Molendijk (MSc), from Lievense, a consultancy firm, presented a large-quantity, low-height storage variant, called the ‘energy island’. The artificial island consists of a dike constructed around a deep well. Seawater gushing into the well through a set of turbines delivers 1,500 megawatt of electricity. Excess power is needed to pump the water back into the surrounding sea. The plan places the island west of Zeeland province, because there the dense clay at a depth of about 30 meters is expected to provide a watertight bottom to the well.

The underground storage system presented by Royal Haskoning works the other way: relatively little water, but at a relatively great height of 1,400 meters. A storage lake (measuring 500 x 600 meters) can be drained to an enormous underground cistern, powering seven, 200 megawatt high-pressure turbines. Two and a half million cubic meters of water rush down a pipe measuring seven metres in diameter. The unit can deliver maximum power for just under six hours and needs only 30 seconds to get online. Building it will take seven years, but it could last for a century.
“Build them”, said Duivendijk, “and then get invited by other countries to do the same over there.”

The same applies to the plans for the tidal energy plant at the Brouwersdam. Opening up the dam to the Grevelingen Lake would partially restore the tide there (up to 0.7 metres). According to Leslie Moyaart (Royal Haskoning), the dam could deliver 60 megawatts, which is sufficient for providing energy to 60,000 homes.
It’s no surprise that Van Duivendijk supervised Moyaart’s MSc thesis. 


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