What is a sand motor and how can it protect against rising sea levels?

Rising sea levels caused by the climate crisis are threatening to inundate coastal cities, towns and villages around the world. The UN calculates that tens of millions of people face the prospect of being forced to leave the places their families have called home for generations.

Reducing greenhouse gas emissions is the most effective way to protect these communities, but other innovative solutions can mitigate against the impact of rising sea levels.

One such innovation is the “sand motor”, which helps to slow down, or even reverse the loss of beaches along at-risk coastlines. The Netherlands built the world's first sand motor in 2011.

The first thing to know is that it is not a motor at all. There is no engine and no mechanical parts. A sand motor is a nature-based solution to coastal erosion that works in harmony with the movement of seawater.

Using millions of tonnes of sand, engineers create sand motors by extending a section of the shoreline out into the sea, creating an artificial peninsula. The ocean’s wave action acts as a "motor" that pushes the sand along the coastline as time passes. As a result, the beach gradually regenerates and the coast is protected from erosion.

It’s now 13 years since the first Dutch sand motor was created and the shoreline is thriving, including the formation of new sand dunes up to three metres in height.

Data from the World Bank shows West African nations are losing $3.8 billion each year as a result of coastal erosion, flooding and pollution.

To reduce the impact, the World Bank is funding a number of regeneration projects in the region. These projects use, or closely replicate, the principles of the Dutch sand motor.

On the coast of Benin a sand motor is regenerating a beach where erosion was having a negative impact on fishing and tourism. In parts of Benin, the shoreline is retreating as much as 13-14 metres every year.

The Dutch engineering company Boskalis built the Benin sand motor which will protect the future of coastal communities as sea levels continue to rise.

In Senegal, coastal communities are building tidal barriers known as groynes to stop the beaches being washed away. The groynes extend out into the water at an angle, in much the same way as a sand motor does. These barriers interrupt the sweeping motion of waves along the beach, adding more than 30 metres of sand to the coast.

The World Economic Forum’s Global Risks Report 2024 details the danger of failing to adapt quickly enough to the impacts of our changing climate.

“Long lead times for developing appropriate infrastructure may challenge readiness for regional or local changes that manifest abruptly,” it says. “For example, the collapse of coral reef systems – which absorb more than 90% of wave energy – could leave coastal communities vulnerable to storm surges.”

Developing infrastructure such as sand motors takes time and money – and delays, says the report, mean controls may arrive too late.