KSB fishes energy for an entire city out of the ocean: the Thassalia marine thermal energy project in Marseille

1. Customer

The French ENGIE Group, based in Paris, is one of the world’s largest energy producers and energy service providers with over 150,000 employees in about 70 countries. Apart from conventional energy generation, the company also focuses on renewable energy sources such as wind power, hydropower and thermal energy.

2. Project

For the population of coastal areas the ocean offers huge energy potentials – which can now, for the first time, be tapped into on a large scale, with KSB’s contribution: In October 2016, Thassalia, a 35 million euro marine thermal plant, was inaugurated in the port of Marseille. The plant harnesses the thermal energy provided by the Mediterranean, supplying sustainable energy for buildings with a 500,000 m² surface area in the new Eco-Cité Euroméditerranée, currently the largest urban renewal project in Southern Europe.

The Thassalia plant significantly contributes to the Eco-Cité Euroméditerranée meeting the French High Quality Environmental Standard for green building. The plant reduces greenhouse gas emissions by 70 %, power consumption by 40 % and water consumption by 65 %.

3. Challenges

KSB was in charge of designing a network for hot and cold water for the entire Eco-Cité district – a highly demanding project, for many reasons:

  • Combined heating and cooling supply
  • Aggressive seawater as transfer fluid
  • Large total area of the Eco-Cité spanning 480 hectares
  • High efficiencies to ensure the lowest possible power consumption
  • Lowest possible noise emissions to protect the people living nearby
  • Fast on-site service for maintenance and repair ensuring smooth operation of the plant 24/7

4. Solution

Seawater from a depth of seven metres is pumped to the thermal system by six high-performance pumps of the CPKN type. Each of these seawater pumps is fitted with a 160 kW variable speed motor. The total flow rate equals 1000 l/s. The aggressive nature of seawater that is heated up to 30 °C in the return system requires the seawater pumps to be well protected against corrosion. All parts in contact with water are therefore made of a special duplex stainless steel – a material developed by KSB called Noridur®. For the same reason, the discs of the ISORIA butterfly valves installed are coated with Halar.

CPKN standardised chemical pump used as seawater pump Six standardised chemical pumps of the CPKN type from KSB are used as seawater pumps, transporting seawater taken from the bay of Marseille at temperatures of up to 30 °C. © Thassalia

The valves with sizes of up to DN 700 fulfil shut-off and control functions during seawater intake. They are actuated by robust pneumatic or manual actuators. The seawater, which ranges in temperature from about 14 °C in winter to 22 °C in summer, supplies the heat exchangers connected to the thermo-refrigeration pumps. It provides heating when the water is cold and cooling when it is warm. Heating or cooling is then distributed to the Eco-Cité buildings via a hot water network of 60 °C and a separate cooling water network of 5 °C.

The network with a length of three kilometres requires high-performance pumps for both circuits. The two circuits are each fitted with four powerful standardised chemical pumps of the MegaCPK type. Each of these pumps can achieve heads of between 110 m and 120 m of water. The motor ratings range from 160 kW to 355 kW with an efficiency of up to 84 % at speeds of 1500 rpm to 1750 rpm.  

KSB's MegaCPK volute casing pump for handling aggressive liquids Eight standardised chemical pumps of the MegaCPK type with motor ratings between 160 and 355 kW are installed in the hot water network and separate cooling water network of the ÉcoCité's buildings. © Thassalia

Data I Facts I Figures 

Employees:153,090 (in 2016)
Sales revenue:66.6 billion euros (in 2016)
IndustryEnergy supply
Thassalia project data
Size of the area to be supplied with hot and cold water480 hectares with a building surface area of 500,000 m2
KSB type series used in this project
Fluid handled:
  • 6 KSB CPKN pumps as seawater pumps with 160 kW variable speed motors,
    wetted parts made of corrosion-resistant Noridur®
  • 6 ISORIA butterfly valves with Halar-coated discs seawater at a temperature of up to 30 °C
Supply network:
  • 8 MegaCPK standardised chemical pumps with motor ratings of 160 to 55 kW (efficiency up to 84 % at speeds between 1500 rpm and 1750 rpm)

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