The City of Amsterdam is building a series of artificial islands for new housing. One of them is Centrumeiland. Its size is 13 ha. (130,000 m2). Its creation requires 800,000 m3 of sand (Source), i.e. approx. 6 m3 per m2.
The method of construction is the “pancake method” (Source):
When an island is built-up this way, porous screens are placed in the water to hold the island’s shape and sand is sprayed into the screens to form a layer of batter-like sludge. As this layer settles and drains through the fine mesh, it hardens and another layer of sand is sprayed on top. Pancake by pancake, the island rises until it is two meters above the water level.
The sand comes from the bed of the IJsselmeer in which the islands are located (Source), so probably some 20-50 km away.
I wondered how energy intensive this practice is.
Could it be done with renewable energy (windmills powering pumps)?